Every lab marker. Explained.

This test measures how much iron has been bound by transferrin.

Transferrin is a protein found in the blood that binds iron to transport it throughout the body. Therefore, having enough transferrin is important for making sure that your body can effectively use the iron you get from your diet.

Transferrin saturation is calculated by dividing iron levels by the Total Iron-Binding Capacity (TIBC) or by transferrin. These two approaches may give slightly different results [R, R].

Transferrin saturation is considered an important marker of your iron status, which means that it can help diagnose iron deficiency or excess iron (iron overload) [R].

This test measures the levels of alkaline phosphatase (ALP).

Alkaline phosphatase is a zinc-containing enzyme that helps break down proteins. It is found in all tissues, but it's most abundant in the bones, liver, kidneys, gut, and placenta [R].

Its major function is to protect your gut against bacteria, aid in digestion, break down fats and some B vitamins, and promote bone formation [R].

Excess or insufficient levels of this enzyme are linked to a broad range of diseases [R].

When the liver is not functioning properly, ALP is released into the bloodstream. Additionally, any condition that affects bone growth or causes higher bone cell activity can increase ALP levels in the blood. For this reason, an ALP test is commonly used to help diagnose liver or bone disorders [R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of alanine aminotransferase (ALT) in your blood.

ALT is an enzyme that breaks down proteins for energy. It is mainly found in the liver, but also in smaller amounts in the kidneys, heart, muscles, fat tissue, intestines, and pancreas [R]. 

Normally, blood ALT levels are low. However, when the liver is injured, ALT leaks into the bloodstream. That's why an ALT test is done to monitor liver health and find out if the liver is damaged or diseased [R]. 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the levels of aspartate aminotransferase (AST).

AST is an enzyme that breaks down proteins for energy. It is found mainly in the liver and heart, but also in many other tissues, including the muscles, red blood cells, kidneys, and the brain. When any one of these tissues is damaged or diseased, AST is released into the blood [R, R]. 

AST levels are often measured to check overall liver health. However, as mentioned above, increases in AST levels can also be due to damage to other organs, such as the heart, kidneys, or muscles. Therefore, AST is often paired with other tests in order to determine the specific location of the problem.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of albumin in your blood.

Albumin is the most abundant protein in the blood. It has several important functions. It [R, R, R, R]:

• keeps fluids inside blood vessels and maintains blood volume.
• binds and transports hormones, vitamins, fatty acids, and minerals around the body.
• serves as the main antioxidant in the blood. 

Albumin is made in the liver. Albumin levels increase in response to hormones such as insulin and decrease when the liver has to make other proteins, in response to infection or inflammation. Albumin can also decrease due to nutritional deficiencies, and liver and kidney damage or disease [R].

Finally, albumin levels tend to decrease as we age [R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

The urine albumin test, also called microalbumin, detects and measures a protein called albumin in your urine.

Albumin is a blood protein that is normally not found in the urine. When kidneys are functioning properly, they don't allow the passage of proteins, including albumin, from the blood into urine. That's why albumin in the urine (microalbuminuria) is an early marker of kidney disease [R, R, R].

Albumin in the urine is common in people with diabetes and/or high blood pressure [R, R]. If you have any or both of these conditions, your doctor will likely order this test at regular intervals.

Albumin can be measured in random urine, timed urine (over a couple of hours), or 24-hour urine. To improve accuracy, albumin is often checked together with urine creatinine (albumin/creatinine ratio), which increases with higher urine concentration [R, R, R].

Taking steps to lower your urine albumin excretion may help decrease your risk of heart and kidney disease in the future [R, R].

The albumin/globulin ratio, or A/G, compares the amount of albumin in your blood to the amount of globulins.

Albumin is made in the liver and helps transport nutrients, hormones, and metabolic products. It also prevents fluid from leaking out of blood vessels (maintains the osmotic pressure) [R].

Globulins are made by either liver or immune cells. They include carrier proteins, enzymes, antibodies (immunoglobulins), and other proteins [R].

The albumin/globulin ratio can be used to check for inflammatory, immune, or digestive disorders.

This test measures the levels of amylase, an enzyme that breaks down complex carbs into simpler ones. 

Digestion of carbs is extremely important since carbs are ultimately broken down to glucose — the main energy source that fuels our bodies.

Since amylase breaks down carbs, it is no surprise that the more amylase you have, within the normal range, the better your body can digest and use of complex carbs [R, R].

There are two main types of amylase - salivary and pancreatic [R, R]. Blood (serum) amylase consists of approximately equal amounts of both. Therefore, abnormal levels of either will affect the total blood levels [R, R].

Salivary amylase is produced by salivary glands and it starts digesting food as you chew it [R].

Pancreatic amylase is produced by the pancreas and helps digest complex sugars in your gut [R].

Most often, your doctor will order an amylase test if they suspect issues with your pancreas, such as inflammation (pancreatitis). Symptoms of pancreas inflammation include [R, R]:

• Moderate to severe abdominal or back pain
• Nausea
• Vomiting
• Loss of appetite
• Oily stools

However, if you want to know for certain whether you have pancreatitis, the amylase test is not enough. Amylase can be increased or decreased by many different causes. Lipase, for example, is a better test of pancreas function.

If needed, your doctor will order specific tests that differentiate between pancreatic and salivary-type amylase [R].

This test looks at the balance of ions in your blood. 

It is calculated as the difference between the sum of the positively charged ions (cations) in the blood, sodium, and sometimes potassium, and the negatively charged ions (anions), CO2/bicarbonate and chloride [R].

Because the concentration of potassium in the blood is low and fairly constant compared to other ions, it's a common practice to remove the potassium from the calculation [R, R].

To maintain a neutral blood pH, the amount of positively and negatively charged ions in the blood is well balanced. However, the electrolyte blood test does not measure all ions present in the blood, such as blood proteins, many of which are negatively charged.  That is why this test can also tell us something about the anions not being measured -- and hence the name - anion gap [R, R].

Your doctor may use the anion gap to help detect acid-base disorders. This test is not specific as to the cause, but can suggest certain metabolic or respiratory disorders, or the presence of some toxins.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test looks at the levels of Anti-Müllerian hormone (AMH) in your blood.

AMH is a hormone made in the ovaries. AMH steadily declines over a woman's childbearing years and eventually becomes undetectable in menopause. 

Doctors use AMH levels, together with other hormone tests, such as estradiol, FSH, or LH, to:

• Evaluate a woman's fertility by estimating the remaining egg maturation potential (ovarian reserve) 
• Estimate the likelihood of conceiving
• Predict the onset of menopause
• Evaluate polycystic ovary syndrome (PCOS)
• Monitor the treatment and recurrence of AMH-producing ovarian cancers

AMH can, for example, be measured in women undergoing in vitro fertilization (IVF).

Keep in mind that AMH is not considered a diagnostic or "stand-alone" test. Your doctor will interpret your result, taking into account your medical history, symptoms, and other test results.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of apolipoprotein B in your blood.

Apolipoprotein B (apoB) is a large protein that serves as the structural backbone of three important lipoproteins. These are called your “bad cholesterol” [R]: 

• low-density lipoprotein (LDL)
• very-low-density lipoprotein (VLDL)
• intermediate-density lipoprotein (IDL)

Each molecule of LDL, VLDL, and IDL contains one molecule of apoB. This means that apoB is a measure of the number of particles that carry "bad cholesterol" in your blood [R]. 

Bad cholesterol that contains ApoB (like LDL) is the main cause of heart disease. Research suggests that ApoB may better predict heart disease than other labs such as LDL cholesterol and triglycerides [R, R, R, R, R, R, R, R, R].

Your doctor may order ApoB to assess your risk of heart disease if you have a family history of heart disease or risk factors for heart disease.

This test measures the content of arachidonic acid (AA or ARA), an omega-6 fatty acid, in your blood. The result is given as the percent of total fatty acids. 

Arachidonic acid is not an essential fatty acid, but its metabolites are important for [R, R]:

• Proper immune system function
• Muscle growth
• Brain function
• Mood
• Appetite

Arachidonic acid has both inflammatory and anti-inflammatory effects [R, R].

Deficiency of omega-6 acids, including arachidonic acid, can cause issues such as hair loss, anemia, fatty liver, and infertility. On the other hand, larger amounts of omega-6 over omega-3 acids have been linked to a higher risk of heart disease [R].

This test looks at the inflammation in your body by looking at the ratio of AA (arachidonic acid) to EPA (eicosapentaenoic acid) in your blood.

Both AA and EPA are important for your health. AA is an omega-6 fatty acid that helps with muscle growth and repair, as well as brain function. Meanwhile, EPA is an omega-3 fatty acid and is important for growth, brain function, and heart health. However, while omega-6 fatty acids are largely pro-inflammatory, omega-3 fatty acids are anti-inflammatory [R, R]. That is why having the right AA/EPA ratio is important.

Your AA/EPA ratio is normally used to assess whether or not you have an increased risk of heart disease or other chronic inflammatory disorders [R].

This test measures the amount of urea in your blood, also known as blood urea nitrogen or BUN.

Urea is a waste product made when the liver breaks down protein. It's removed by the kidneys [R, R, R].

In a nutshell, BUN indicates how well your kidneys are functioning. You should keep track of your kidney function, especially if you are dealing with chronic issues such as obesity or diabetes.

Overall, kidney function is best evaluated when looking at BUN and creatinine together - which is called the BUN/creatinine ratio [R]. 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

BUN (blood urea nitrogen) and creatinine are two lab tests that are often measured as a part of a comprehensive metabolic panel. Your doctor may order this panel to get an idea of your overall health and metabolism.

BUN measures the amount of urea in your blood. Urea is a waste product made in the liver as the body processes protein. This protein is mostly derived from the diet, but it can also result from tissue protein turnover [R, R, R]. 

Urea is removed by the kidneys, but the rate of removal depends on the needs of the body -- kidneys can return different amounts of urea into the bloodstream depending on factors such as hydration and blood pressure [R, R, R].

Creatinine, on the other hand, is a waste product created from the normal wear and tear of muscles. It is produced from creatine, a protein that helps generate energy for muscle contractions. Creatinine production essentially reflects lean body mass, and because this mass changes little from day to day, the production rate is also fairly constant [R, R, R]. 

Creatinine is removed from the body by the kidneys, which filter almost all of it from the blood into the urine, at a fairly constant rate. That is why blood levels are usually a good indicator of how well your kidneys are working [R, R, R]. 

So, to recap, while BUN levels fluctuate because kidneys can return urea into the bloodstream depending on the body’s needs, creatinine gets removed at a constant rate and its blood levels are usually stable [R]. That's why the BUN/creatinine ratio can be used to check for issues such as dehydration, kidney injury/disease, gut bleeding, etc.

This test detects bacteria in your urine.

Normally there are few or no bacteria present. An increased number of bacteria can mean you have a urinary tract infection. Alternatively, it can mean that the sample was contaminated by genital secretions [R, R, R].

Urinary tract infection (UTI) is a collective term that describes any infection involving parts of the urinary tract: the kidneys, ureters, bladder, and urethra. These Infections occur when bacteria enter the urinary tract. Women have shorter urethras than men and are therefore more susceptible -- they are about 30 times more likely to develop a UTI. Escherichia coli is the most common microbe causing UTI [R, R].

Factors that can increase the risk of UTI include:

• Advanced age [R]
• Immobility [R, R]
• Urinary catheterization [R, R, R, R]
• Urinary surgical procedure [R]
• Urinary obstruction because of a blockage in the bladder or urethra (kidney stones, tumor) [R, R]
• Urinary retention, i.e. difficulty emptying the bladder [R]
• Narrowed urethra [R]
• Enlarged prostate [R, R] 
• Bowel incontinence [R]
• Pregnancy [R]
• Diabetes [R, R]
• Nervous system conditions that affect bladder function, like multiple sclerosis or Parkinson's [R]
• Weakened immune system after a kidney transplant, or due to drug-induced immunosuppression, or conditions such as AIDS [R, R, R, R, R]

This test checks what percentage of your white blood cells is made of basophils.

Basophils are white blood cells. They help protect against infections, but they can also play a role in autoimmune diseases and allergies [R, R].

Normally, basophils constitute less than 2% of all your white blood cells.

Your doctor will interpret this test, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the levels of basophils in the blood.

Basophils are white blood cells. They help protect against infections, but they can also play a role in autoimmune diseases and allergies [R, R].

Normally, basophils constitute less than 2% of all your white blood cells.

Your doctor will interpret this test, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the levels of direct or conjugated bilirubin in your blood.

Bilirubin is a waste product produced by the normal breakdown of red blood cells. In the liver, it gets converted into conjugated (direct) bilirubin [R, R].

After being further processed by the liver and bile, direct bilirubin gets released into the gut and is eventually eliminated in the stool. The final product of bilirubin, stercobilin, is responsible for giving stool its brown color [R].

This test is usually used to check for liver and bile disease.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the levels of indirect bilirubin in your blood.

Unconjugated (indirect) bilirubin is an orange waste product produced by the normal breakdown of red blood cells. Unconjugated bilirubin is carried through the bloodstream to the liver. There, it is converted into conjugated (direct) bilirubin to start its elimination from the body. This test measures the levels of indirect or unconjugated bilirubin in your blood [R, R].

This test is usually used to check for liver disease.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal. 

Consuming vitamin C (≥0.5 g/day) may interfere with the tests. Stop taking vitamin C at least 3-4 days before your blood test [R].

This test measures bilirubin, a yellow pigment produced in the normal breakdown of red blood cells.

Bilirubin is produced from hemoglobin, the compound in red blood cells that allows them to carry oxygen. As red blood cells are broken down, the iron-containing part of hemoglobin (heme) is converted to bilirubin.

Bilirubin passes through two phases. In the first phase, bilirubin binds to a protein called albumin, which allows it to be carried from the blood and into the liver. Bilirubin in this phase is called “indirect” or “unconjugated” bilirubin.

The second phase takes place in the liver, which attaches sugar molecules to the “unconjugated” bilirubin. This makes it water-soluble, which helps the gut eliminate bilirubin in the stool. Bilirubin in this phase is called “direct” or “conjugated” bilirubin.

Total bilirubin is the sum of your direct and indirect bilirubin levels. Its yellow color is responsible for the yellow skin discoloration encountered in jaundice [R].

However, bilirubin is not just a waste product. In recent decades, science has been uncovering the beneficial roles bilirubin plays in our bodies. Research suggests that bilirubin may act as a powerful antioxidant and anti-inflammatory agent and that it may protect against chronic inflammation and heart disease [R, R, R, R, R, R, R, R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal. 

Refrain from taking high doses of vitamin C (>4 g) within a day before testing, as this can interfere with the test [R].

This test measures the amount of C-peptide in your blood. C-peptide is a good indicator of how much insulin your body is making.

Insulin is made in the pancreas from a protein called "proinsulin". Its main function is to transport sugar (glucose) from your blood into your cells and tissues [R, R]. 

Each proinsulin breaks down to a molecule of insulin and a molecule of C-peptide, which are released when blood sugar levels are high. Basically, insulin and C-peptide are being released in equal amounts. But while insulin is cleared variably, C-peptide is removed at a constant rate. This means that C-peptide is a more dependable measure of insulin production [R, R].

Your doctor may order a C-peptide test to [R]:

• Measure the production of insulin made in your body (it can differentiate between insulin produced internally in the body and externally taken as medication)
• Differentiate between type 1 diabetes (when the pancreas doesn't produce enough insulin) and type 2 diabetes (when the body doesn't use insulin that's produced as well as it should). It's especially useful in adult-onset autoimmune diabetes (LADA or type 1.5 diabetes) which is often misdiagnosed as type 2 diabetes. 
• Monitor diabetes. Your doctor can use this test to decide whether you need to take insulin, or to adjust the dosage if you are already taking it 
• Investigate the reason of your low blood sugar levels (hypoglycemia) 
• Diagnose a tumor of the pancreas or monitor the situation after pancreas removal or transplantation

C-peptide was initially considered inactive -- a mere byproduct of insulin production. But studies show that this peptide actually has both anti-inflammatory and pro-inflammatory effects in the body, depending on its levels [R, R, R]. In a nutshell, you would want C-peptide (and insulin production) to be balanced - neither too high nor too low.

C-peptide levels (and insulin production) increase with weight (fat mass) and age in non-diabetics [R]. On the other hand, in diabetics, C-peptide declines over decades with the duration of diabetes [R].

This test measures the amount of C-reactive protein (CRP) in your blood.

CRP is a protein made in the liver in response to [R, R]:

• injury
• inflammation
• infection

CRP binds to damaged tissue or microbes and tags them so the immune system can clear them away [R, R]. 

Your doctor may order this test if they suspect an inflammatory condition, such as a bacterial infection, autoimmune disorder, or inflammatory bowel disease (IBD). Doctors can use this test both to check for inflammation and to monitor the response to treatment.

This CRP test should not be confused with the high-sensitivity CRP test (hs-CRP), which measures a different range or CRP for different purposes. This test measures highly elevated CRP levels that correspond to significant inflammation (8 -1000 mg/L). hs-CRP, on the other hand, detects low levels of CRP, in order to get an estimate of chronic low-grade inflammation in the body (0.3 - 10 mg/L). The hs-CRP can be used to evaluate a person's risk of heart disease [R].

This test looks at the amount of CD57+ natural killer cells in your blood.

Natural killer (NK) cells are a type of white blood cell that play important roles in the immune response. 

The CD57+ test is a test used by some doctors to evaluate and follow people diagnosed with chronic Lyme disease. 

Chronic Lyme disease is a controversial term used for people who have persistent or recurrent nonspecific symptoms (such as fatigue, muscle or joint pain, and brain fog) in people who have had Lyme disease and have received an adequate course of antibiotic therapy.

Some reports suggest that people with chronic Lyme disease have a decreased number of CD57+ NK cells. While this is debated at the moment, conditions often confused with chronic Lyme, such as multiple sclerosis, lupus, and rheumatoid arthritis, are not linked to low CD57+.

The issue with the test is that there are also reports of high CD57+ NK cells in people with Lyme disease and low levels in people in remission. Other studies found no difference in CD57+ between people with Lyme disease and healthy controls.

It's important when getting this test to make sure it's actually counting CD57+ NK cells (CD8- or CD8-/CD3-) and not CD57+ T cells (CD8+ or CD3+).

This test looks at the relative amount of CD57+ natural killer cells in your blood.

Natural killer (NK) cells are a type of white blood cell that play important roles in the immune response. 

The CD57+ test is a test used by some doctors to evaluate and follow people diagnosed with chronic Lyme disease. 

Chronic Lyme disease is a controversial term used for people who have persistent or recurrent nonspecific symptoms (such as fatigue, muscle or joint pain, and brain fog) in people who have had Lyme disease and have received an adequate course of antibiotic therapy.

Some reports suggest that people with chronic Lyme disease have a decreased number of CD57+ NK cells. While this is debated at the moment, conditions often confused with chronic Lyme, such as multiple sclerosis, lupus, and rheumatoid arthritis, are not linked to low CD57+.

The issue with the test is that there are also reports of high CD57+ NK cells in people with Lyme disease and low levels in people in remission. Other studies found no difference in CD57+ between people with Lyme disease and healthy controls.

It's important when getting this test to make sure it's actually counting CD57+ NK cells (CD8- or CD8-/CD3-) and not CD57+ T cells (CD8+ or CD3+).

This test measures the amount of calcium in your blood, considering the levels of albumin, a blood protein.

Calcium is the most abundant mineral in the human body. Approximately 99% of the calcium in our bodies is in our bones and teeth. The remaining 1% of calcium circulates in the blood [R]. 

Apart from keeping our bones and teeth strong, calcium also plays a crucial role in nerve and muscle function, blood clotting, and proper enzyme function [R]. 

Calcium levels in the blood are tightly controlled by parathyroid hormone (PTH) and vitamin D. If blood levels drop, calcium is taken from bones to keep blood levels stable [R].

In the blood, 45% of calcium is bound to albumin and is inactive. Another 10% is combined with anions. This leaves 45% of free and active calcium that can be used by our bodies for various functions [R]. 

The concentration of calcium in the body may be affected by several different factors, including albumin concentration. Hence, doctors may “adjust” or “correct” total calcium for albumin concentration: adjusted or corrected calcium [R].

However, adjusted calcium may not be an accurate measure of calcium status in certain people, especially those with advanced kidney disease or critically ill. Hence, doctors may order an ionized calcium test to confirm the result [R, R, R, R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test tells you how much carbon dioxide (bicarbonate) you have in your blood.

Bicarbonate is a negatively charged ion that helps maintain the body's acid-base (pH) balance [R]. 

Bicarbonate (HCO3) is formed from carbon dioxide (CO2), which is released into the blood as a waste product when your body burns food to create energy [R]. 

Measuring bicarbonate can help uncover acid-base imbalances in your body [R].

Lungs and kidneys are the major organs that control the amount of bicarbonate in the blood. Any condition that disturbs the kidneys, lungs (breathing), or your metabolism, has the potential to disturb the body’s acid/base balance [R]. 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the level of chloride in your blood.

Chloride is a negatively charged ion. Along with sodium, potassium, and bicarbonate, it helps balance the amount of fluids in the body. Chloride is also important for the acid-base balance (pH) in the blood.

We get chloride through our diet -- it's found in table salt (sodium chloride) and also in various vegetables. Chloride levels are adjusted by the kidneys, which control how much chloride is going to be lost through urine.

Blood chloride levels are generally steady, although they can drop slightly after meals. This is because the stomach produces acid after eating, for which it uses chloride from blood.

Chloride levels usually mirror the level of sodium. However, if there is an acid-base imbalance in your body, chloride levels can change independently of sodium levels [R, R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of total cholesterol in your blood.

Cholesterol is a fat-like substance that's a key component of cells. It's also used by the body to make steroid hormones (testosterone, estrogens, cortisol, aldosterone, etc.), bile, and vitamin D [R].

Cholesterol that's found in the blood is bound into particles called lipoproteins. You can think of lipoproteins as the vehicle and cholesterol as the passenger. These lipoproteins differ in density (vehicle size), based on which there are three types of cholesterol:

• HDL-cholesterol (high-density lipoprotein cholesterol), known as the “good” cholesterol
• LDL-cholesterol (low-density lipoprotein cholesterol), known as the “bad” cholesterol
• VLDL-cholesterol (very-low-density lipoprotein cholesterol), also “bad” cholesterol

Total cholesterol is the sum of these three types of cholesterol in your body. A change in any of these cholesterols will affect your total cholesterol score.

HDL-cholesterol is known as “good" cholesterol because HDL particles carry it away for disposal. LDL-cholesterol, on the other hand, is considered "bad" cholesterol because LDL particles deposit it in tissues such as the arteries [R, R, R].

Higher levels of total cholesterol have been associated with hardening of the arteries and heart disease. That's why it's important to monitor your cholesterol levels and maintain them in a healthy range [R, R].

Total cholesterol increases as we age up to around 50 years of age. It remains elevated until about 70 when it decreases gradually [R].

Experts recommend that you check your cholesterol regularly, about every 5 years, or more often if you have a higher risk of heart disease, due to factors such as [R]:

• A family history of heart disease
• Smoking
• Being overweight/obese
• Having diabetes or high blood pressure

This test calculates the ratio between total cholesterol and "good" cholesterol (HDL-C) levels, also known as the cholesterol ratio.

This ratio helps estimate heart disease risk [R, R].

In general, the smaller the number the better, as this means that the HDL-C (“good cholesterol”) is high compared to "bad" cholesterol [R].

This test measures the amount of cortisol in your blood.

Cortisol is a steroid hormone produced by the adrenal glands. Although it has many different functions in the body, cortisol is most widely known as a “stress” hormone that initiates the body’s “fight-or-flight” response. This helps the body react to stress by shifting it into an “emergency mode” where resources are conserved and non-critical functions are put on hold. In other words, cortisol makes your body focus on “short-term” processes (such as making energy) at the expense of “long-term” ones (like growth, digestion, and reproductive and immune system function) [R, R].

Cortisol helps control the metabolism of fats, proteins, and carbs, and regulates blood pressure, the immune system, and inflammation [R, R, R, R, R].

Cortisol is one of the major regulators of blood sugar levels. Cortisol causes stored glucose to be released into the blood supply where it can be used immediately by the body. However, it also signals the body to store any incoming glucose, which is why chronically high cortisol levels can lead to weight gain rather than weight loss [R, R, R, R].

Cortisol levels vary naturally throughout the day. Its levels are generally highest in the morning after waking, and gradually decrease throughout the day (however, this is often reversed in people who work at night) [R, R].

Cortisol levels also rise naturally:

• After eating [R]
• After physical activity/exercise [R, R, R, R, R]
• In response to physical and psychological stress [R, R, R, R, R, R]

Cortisol is essential for health and well-being and can lead to significant health problems when its levels are too low or too high. Very high or low values can be markers of chronic conditions such as hypercortisolism (e.g. Cushing syndrome) and hypocortisolism (e.g. Addison’s disease) [R].

Most cortisol tests take a single measurement -- ideally during the early morning, shortly after waking -- which presents only a limited picture of one’s cortisol activity [R, R]. Because cortisol levels generally peak in the morning and fall throughout the day, one of the most reliable ways to detect abnormally high cortisol activity is by testing it in the evening or nighttime. If cortisol levels are still high during this period, a disorder is more likely. Also, tracking your cortisol levels over time may be a good idea.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of cortisol in your blood in the morning.

Cortisol is a steroid hormone produced by the adrenal glands. Although it has many different functions in the body, cortisol is most widely known as a “stress” hormone that initiates the body’s “fight-or-flight” response. This helps the body react to stress by shifting it into an “emergency mode” where resources are conserved and non-critical functions are put on hold [R, R]. 

In other words, cortisol makes your body focus more purely on “short-term” processes (such as glucose metabolism) at the expense of “long-term” ones (like growth, digestion, and reproductive and immune system function) [R, R].

Cortisol is one of the major regulators of blood sugar levels [R, R]. Cortisol causes stored glucose to be released into the blood supply where it can be used immediately by the body [R]. However, it also signals the body to store any incoming glucose, which is why chronically high cortisol levels can lead to weight gain rather than weight loss [R].

Cortisol also helps control the metabolism of fats, proteins, and carbs and regulates blood pressure, the immune system, and inflammation [R, R, R, R, R].

Cortisol levels vary naturally throughout the day [R]. Its levels are generally highest in the morning after waking, and gradually decrease throughout the day (however, this is often reversed in people who work at night) [R].

Cortisol levels also rise naturally:

• After eating [R]
• After physical activity/exercise [R, R, R, R, R]
• In response to physical and psychological stress [R, R, R, R, R, R]

Cortisol is essential for health and well-being and can lead to significant health problems when its levels are too low or too high. Very high- or low- values can be markers of chronic conditions such as hypercortisolism (e.g. Cushing syndrome) and hypocortisolism (e.g. Addison’s disease) [R].

The cortisol AM test is taken during the early morning, shortly after waking (around 8 am) -- which presents only a limited picture of one’s cortisol activity [R, R]. Because cortisol levels generally peak in the morning and fall throughout the day, one of the most reliable ways to detect abnormally high cortisol activity is by testing it in the evening or nighttime. If cortisol levels are still high at night, a disorder is more likely. 

Also, tracking your cortisol levels over time may be a good idea.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of cortisol in your blood in the evening.

Cortisol is a steroid hormone produced by the adrenal glands. Although it has many different functions in the body, cortisol is most widely known as a “stress” hormone that initiates the body’s “fight-or-flight” response. This helps the body react to stress by shifting it into an “emergency mode” where resources are conserved and non-critical functions are put on hold [R, R]. 

In other words, cortisol makes your body focus more purely on “short-term” processes (such as glucose metabolism) at the expense of “long-term” ones (like growth, digestion, and reproductive and immune system function) [R, R].

Cortisol is one of the major regulators of blood sugar levels [R, R]. Cortisol causes stored glucose to be released into the blood supply where it can be used immediately by the body [R]. However, it also signals the body to store any incoming glucose, which is why chronically high cortisol levels can lead to weight gain rather than weight loss [R].

Cortisol also helps control the metabolism of fats, proteins, and carbs, and regulates blood pressure, the immune system, and inflammation [R, R, R, R, R].

Cortisol levels vary naturally throughout the day [R]. Its levels are generally highest in the morning after waking, and gradually decrease throughout the day (however, this is often reversed in people who work at night) [R].

Cortisol levels also rise naturally:

• After eating [R]
• After physical activity/exercise [R, R, R, R, R]
• In response to physical and psychological stress [R, R, R, R, R, R]

Cortisol is essential for health and well-being and can lead to significant health problems when its levels are too low or too high. Very high- or low- values can be markers of chronic conditions such as hypercortisolism (e.g. Cushing syndrome) and hypocortisolism (e.g. Addison’s disease) [R].

This test is taken during the afternoon (around 4 pm). Because cortisol levels generally peak in the morning and fall throughout the day, one of the most reliable ways to detect abnormally high cortisol activity is by testing it later in the day or at night time. If cortisol levels are still high during this period, a disorder is more likely. However, any single test presents only a limited picture of one’s cortisol activity [R, R]. 

In addition to taking more cortisol measurements, tracking your cortisol levels over time may be a good idea.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the levels of creatinine in your blood.

Creatinine is a waste product of the normal wear and tear of muscles. It is produced from creatine, a protein needed to generate the energy for muscle contractions [R, R]. 

The production of creatinine essentially reflects lean body mass, and because muscle mass changes little from day to day, the production rate is also fairly constant. Women, children, and older people tend to have lower levels of creatinine compared to adult men because they have less muscle mass [R].

Creatinine is removed from the body by the kidneys, which filter almost all of it from the blood into the urine. When kidneys aren't working properly, creatine remains in the blood and builds up. That is why blood creatinine levels can be used to check how well your kidneys are working [R, R]. 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal. The range of this test also depends on your age. Ask your doctor to explain your results.

However, also bear in mind that this test is not very sensitive when it comes to kidney health. Creatinine levels may not increase above normal until more than 50% of total kidney function is lost. A more sensitive test, eGFR, is calculated based on your creatinine value, taking into account your age, gender, and ethnicity -- all of which affect your creatinine levels [R].

This test measures the content of DHA (docosahexaenoic acid), which is a type of omega-3 fatty acid, in your blood. The value is given as the percent of total fatty acids.

DHA is important for growth, brain function, and heart health. DHA may improve attention, memory, and learning. It may also decrease triglyceride levels and help combat inflammation [R, R, R, R, R, R, R].

People are at a higher risk of having lower DHA if they are [R, R, R, R]:

• Overweight
• Smoking
• On a vegan diet 

Although the body can produce DHA from alpha-linolenic acid (ALA), another type of omega-3 fatty acid found in plants, this process is not very efficient. It's better to get DHA directly from food sources such as fish and seafood. Some DHA can also be found in algae [R, R, R].

DHA tests are usually done as a part of an omega-3 and -6 fatty acid panel.

This test measures the amount of dehydroepiandrosterone sulfate (DHEA-S) in your blood.

DHEA is a steroid hormone produced primarily by the adrenal glands. It is also produced to a much lesser extent by the testes and ovaries and possibly the brain [R, R].

The majority of DHEA gets quickly converted into DHEA sulfate (DHEA-S). DHEA-S levels are 100-1000 times higher than DHEA, which makes DHEA-S significantly easier to measure and the reason why most labs test DHEA-S levels instead of regular DHEA [R, R].

Together with DHEA, DHEA-S is the most abundant steroid circulating in the blood and is the precursor to the sex hormones testosterone and estradiol (the primary estrogen) [R]. 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of dihydrotestosterone (DHT) in your blood. 

DHT is a male sex hormone (androgen). In men, it is created from testosterone in the prostate gland, adrenal glands, liver, brain, and hair follicles by the enzyme 5α-reductase. In women it's mostly created from androstenedione [R, R, R]. 

DHT plays a major role in the development of characteristics that are typically associated with men (body hair, muscle growth, and a deep voice) and is necessary for the penis and prostate to fully develop and function. It is almost 3 times more powerful as an androgen than testosterone [R, R]. 

Doctors may order DHT tests to help diagnose male pattern baldness and 5α-reductase deficiency, and monitor prostate cancer patients on DHT-blocking medications [R, R].

This test measures the amount of docosapentaenoic acid (DPA) in your blood.

DPA is an omega-3 fatty acid. It is less well-known than its cousins EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), but it's gaining attention for its potential health benefits. DPA is found in [R, R]:

• Fish oil and fish oil supplements
• Grass-fed beef
• Cold-water fish (e.g., salmon, mackerel, herring)
• Seal oil

DPA has several important functions. It supports [R, R, R, R]:

• DHA and EPA production
• Inflammation
• Immunity
• Wound healing
• Brain health

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of EPA (eicosapentaenoic acid), an omega-3 fatty acid, in your blood. Your EPA is given as the percent of total fatty acids.

EPA is important for growth, brain function, and heart health. It also lowers inflammation, decreases triglyceride levels and may have antidepressant effects [R, R, R, R, R].

Smoking or eating a vegan diet has been associated with lower EPA levels [R, R].

The body can produce EPA from alpha-linolenic acid (ALA), a different omega-3 fatty acid found in plants. This process may be inefficient. It's better to get EPA directly from food sources such as oily fish and shellfish. EPA can also be found in algae [R, R, R]. 

EPA levels may be used along with other fatty acid tests to assess your risk for heart disease.

This test measures the Erythrocyte Sedimentation Rate (ESR) or “sed rate”, which is the rate at which erythrocytes, or red blood cells, sink to the bottom of a sample tube.

ESR indirectly measures inflammation in the body. When there is more inflammation, red blood cells stick together and sink faster [R, R]. 

ESR can't be used alone to diagnose any specific medical condition. In addition, ESR is less reliable than other markers of inflammation, such as CRP [R, R, R].

Your doctor will likely run an ESR test as part of an initial screening. An ESR test can also be useful for monitoring the progress of inflammatory conditions and ensuring the treatment is working [R].

This checks the percentage of white blood cells that are eosinophils.

Eosinophils are white blood cells that play a role in your immune response. They help fight infections, mainly by parasites and are involved in allergies and inflammation [R].

Normally, eosinophils constitute less than 5% of all your white blood cells.

Your doctor will interpret this test, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test looks at the eosinophil count in your blood.

Eosinophils are white blood cells that play a role in your immune response. They help fight infections, mainly by parasites and are involved in allergies and inflammation [R].

Normally, eosinophils constitute less than 5% of all your white blood cells.

Your doctor will interpret this test, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of estradiol in your blood.  

Estradiol (E2) is a sex hormone and the most active estrogen in the body. It's made mainly in the ovaries, however, the brain, fat cells, immune system cells, and bones can also make smaller amounts. It is made by conversion from testosterone, androstenedione, and progesterone, which are also sex hormones [R, R]. 

Estradiol is important for female and male reproduction, brain, thyroid, and bone health, and maintaining a healthy weight [R, R].

In the blood, estradiol exists in two forms. Most of it is bound to proteins (SHBG or albumin), while about 1% is unbound/free. The unbound form is the one that is active, exerting effects on our bodies [R, R]. 

It is difficult to measure or calculate free blood estradiol levels, and thus, most blood estradiol tests only measure bound estradiol [R].

This test measures the amount of estradiol in your blood.  

Estradiol (E2) is a sex hormone and the most active estrogen in the body. It's made mainly in the ovaries, however, the brain, fat cells, immune system cells, and bones can also make smaller amounts. It is made by conversion from testosterone, androstenedione, and progesterone, which are also sex hormones [R]. 

Estradiol is important for female and male reproduction, brain, thyroid, and bone health, and for maintaining a healthy weight. 

In the blood, estradiol exists in two forms. Most of it is bound to proteins (SHBG or albumin), while about 1% is unbound/free. The unbound form is the one that is active, exerting effects on our bodies [R, R]. 

It is difficult to measure or calculate free blood estradiol levels, and thus, most blood estradiol tests only measure bound estradiol [R].

This test measures the amount of estrogen in your blood.  

Estrogens are female sex hormones. Estradiol (E2) is the most active estrogen in the body. Estradiol is important for [R, R]:

• Female and male reproduction
• Brain and thyroid function
• Bone health and development
• Maintaining a healthy weight

The other main estrogens are estrone (E1) and estriol (E3). Both estrone and estriol are weaker estrogens than estradiol. Estrone can be converted into estradiol, while estriol is mostly undetected until a woman becomes pregnant [R].

This test measures the amount of estrone in your blood.

This test measures the amount of the sex hormone estrone in your urine. 

Estrone (E1) is one of the three main types of estrogen found in the body. Estrogens, including estrone, are made in the ovaries, corpus luteum, and placenta. Estrone is also often made in fat tissue and adrenal glands, and can be converted into estradiol (E2) or estriol (E3) [R, R, R]. 

Normally, estradiol levels are the highest in the body. But in women after menopause, estrone becomes the major estrogen after estradiol and estriol levels diminish [R, R, R]. 

Abnormal estrone levels can help doctors shed a light on reproductive issues and infertility problems.

This test measures the amount of follicle-stimulating hormone (FSH) in your blood.

FSH is a hormone involved in reproduction that stimulates the growth and maturation of eggs in women and sperm in men [R, R].

FSH is made by the pituitary gland and its production is controlled by the hypothalamus, pituitary, and the hormones made in the ovaries or testes [R, R].

In women, FSH increases during the first half of the menstrual cycle and then decreases after ovulation. Levels also increase in menopause [R].

Your doctor may order this test if you are [R]:

• Having difficulty getting pregnant
• Having irregular menstrual periods
• Going through menopause
• Having a low sperm count
• Having symptoms of pituitary or hypothalamic disorders
• Having symptoms of testicular or ovarian disease

This test measures ferritin, a protein that stores and transports iron in the blood.

Iron has many important roles in our bodies. For example, it's critical for making red blood cells and it's needed for muscle and heart cells to produce energy. However, iron by itself can be toxic, primarily because it produces free radicals that cause damage to cells and tissues. For this reason, the body uses special proteins like ferritin to safely store and transport iron to where it is needed [R].

Low ferritin levels signal that the body's iron stores are low. Higher levels, on the other hand, may indicate that you have a condition that causes the body to store too much iron [R]. 

However, ferritin also plays a role in the immune response, and increases in conditions such as chronic inflammation, infections, and cancer, irrespective of iron levels [R].

This test, therefore, serves as a measure of the total amount of iron stored in your body, but can also point to inflammatory conditions [R].

This test measures the amount of vitamin B9 in your blood.

Vitamin B9, also known as “folate” or “folic acid”, is a water-soluble vitamin that is involved in a variety of metabolic functions. It:

• is required for making DNA and metabolizing amino acids [R, R, R]
• helps create and grow blood cells [R]
• maintains the health of the nervous system [R]
• acts as an antioxidant [R]

Folate cannot be created in the body and must be acquired from dietary sources, mainly fruits and green leafy vegetables. Vitamin B9 that comes from food is generally referred to as “folate,” while “folic acid” is the synthetic form that is most commonly found in supplements [R, R, R, R]. 

Folate is stored primarily in the liver, with the remainder mostly being found in the blood, which is what this blood test measures [R].

Groups at a higher risk of folate deficiency include [R]:

• Pregnant women
• The elderly
• Alcoholics
• People with gut disorders
• Those who have undergone weight loss surgery
• People suffering from abnormal red blood cell destruction (hemolytic anemia)

Free T4 index (FT4I or T7), or free thyroxine index (FTI), is an index that is calculated from total T4 levels and thyroxine-binding capacity, a measure of the amount of proteins in the blood capable of binding to the thyroid hormone T4. 

Free T4 is low in people with an underactive thyroid (hypothyroidism) and high in those with an overactive thyroid (hyperthyroidism) [R].

The free T4 index was used as an indicator of how well the thyroid gland is working. However, nowadays it's been largely replaced by the direct measurement of free T4.

This test measures the amount of gamma-glutamyl transferase (GGT) in the blood.

Gamma-glutamyl transferase (GGT) is an enzyme mainly found in the liver, gallbladder, kidneys, and pancreas. This enzyme helps break down proteins and also breaks down glutathione, a major antioxidant [R, R].

GGT levels are usually elevated in conditions that cause damage to the liver or bile duct, and to a lesser degree, the kidney and pancreas. This blood test is therefore commonly used to help diagnose potential liver and bile-duct disease [R].

Apart from being a tool that can point to liver disorders and alcohol abuse, a growing body of evidence has established the link between higher GGT levels and inflammation and oxidative stress [R, R, R, R, R, R].

Research has linked higher GGT, even within the normal range, with an increased risk of diabetes, heart disease, kidney disease, and cancer [R, R, R, R]. However, genetic studies found that this relationship likely isn't causal, which means that GGT serves as an indicator that there are health issues in the body, but it's not directly causing them [R, R, R].

This test measures the amount of globulins in your blood.

Globulins are a group of proteins that help fight infections and bind hormones and nutrients, thereby controlling their levels. They include carrier proteins, enzymes, antibodies (immunoglobulins), and other proteins [R]. 

Globulins that transport nutrients and hormones are made in the liver, while those that fight infections are made by the immune cells [R]. 

Globulin levels can signal whether or not you have an inflammatory disorder or infection, because antibody production increases in these conditions [R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the level of glucose in your blood after at least 8 hours of fasting. It's therefore usually done in the morning.

Glucose is a sugar that our body uses to make energy. We get glucose from carbs, such as bread, pasta, cereals, fruits, and fruit juices. When we fast, our body can release glucose from internal stores, or it can create glucose from fats, proteins, and other available sources [R].

Glucose levels are controlled by hormones such as [R]:

• Insulin, which helps move glucose from the blood into tissues
• Glucagon, which helps release glucose from tissues (mainly the liver) into the blood

When you eat, insulin is released into the blood and makes sure that the glucose either gets stored in the liver or taken to tissues such as the brain and muscles where it is used for energy. On the other hand, when you're fasting, glucagon makes sure that your body has enough energy to function properly [R].

This test can tell you if you have trouble controlling your blood sugar levels. It can be used to screen for or help diagnose diabetes, prediabetes, and diabetes in pregnancy (gestational diabetes). It can also be used to monitor blood sugar levels in people who have diabetes.

Apart from diabetes, abnormal levels can point out issues such as insulin resistance, hormonal imbalances, and pancreatic, liver, or kidney disease. 

According to the American Diabetes Association, screening for diabetes is recommended in people over 45 (every 3 years), or at any age if you have certain risk factors, including [R]:

• Being overweight, obese, or physically inactive
• Having a close (first or second-degree) relative with diabetes
• Belonging to a certain race/ethnic group (Native Americans, African-Americans, Hispanic Americans, Asians/South Pacific Islanders)
• Having signs of insulin resistance or conditions associated with insulin resistance, such as high blood pressure (hypertension), low good cholesterol and/or high triglycerides (dyslipidemia), and polycystic ovary syndrome
• Having had diabetes in pregnancy (gestational diabetes)

This test measures the amount of glucose in your blood at a random time of day.

Glucose is a sugar that our body uses to make energy. We get glucose from carbs, such as bread, pasta, cereals, fruits, and fruit juices. When we fast, our body can release glucose from internal stores, or it can create glucose from fats, proteins, and other available sources [R].

Glucose levels are controlled by hormones such as [R]:

• Insulin, which helps move glucose from the blood into tissues
• Glucagon, which helps release glucose from tissues (mainly the liver) into the blood

When you eat, insulin is released into the blood and makes sure that the glucose either gets stored in the liver or taken to tissues such as the brain and muscles where it is used for energy. On the other hand, when you're fasting, glucagon makes sure that your body has enough energy to function properly [R].

A random glucose test is commonly used to screen for diabetes. However, a random glucose test is not sensitive. Depending on your random blood glucose result, your doctor may order a fasting blood glucose test, HbA1c test, or glucose tolerance test to get a more accurate and comprehensive picture of your blood sugar control [R].

This test looks at the percentage of your white blood cells that are granulocytes.

Granulocytes are types of white blood cells. They include:

• Neutrophils
• Eosinophils
• Basophils

These white blood cells are called granulocytes because they all contain small particles (granules) filled with enzymes, that when released into the bloodstream, kill bacteria, viruses, and fungal cells [R, R, R, R]. 

Since neutrophils are the most abundant type of granulocytes in our blood, your granulocyte count is usually mostly dependent on your neutrophil count [R, R].

This test measures the amount of HDL-cholesterol (HDL-C), also known as "good" cholesterol, in your blood.

HDL-cholesterol is cholesterol bound to high-density lipoprotein (HDL) particles, which are made in the liver and consist of proteins and fats (lipids). They help remove excess cholesterol from the blood by [R, R, R]:

• transporting it to the liver, where it becomes a part of bile and is excreted through feces
• taking it to adrenal glands, ovaries, and testes, where cholesterol is converted into steroid hormones (e.g. cortisol, estrogens, testosterone)  

Cholesterol transported by HDL is known as “good" cholesterol because it is being removed from artery walls, which helps prevent, reduce, and even reverse the hardening of the arteries (atherosclerosis) and heart disease [R].

This test measures the number of large HDL particles in your blood.

Cholesterol transported by HDL is known as “good cholesterol” because it helps remove cholesterol from cells and artery walls, which helps prevent, reduce, and even reverse the hardening of the arteries (atherosclerosis) and accumulation of fatty plaques [R, R]. 

HDL particles differ in size and function. Large HDL particles (i.e. HDL2) are believed to be more protective against heart disease. Research suggests that large HDL particles remove cholesterol from artery walls more efficiently. They are also better at preventing blood clots and decreasing inflammation. Also, people with more large HDL particles will usually have fewer LDL particles in the blood, which is heart-protective. Many studies have found that people with high concentrations of larger HDL particles are at lower risk for heart disease [R, R, R].

This test looks at the size of HDL particles in your blood.

You may already know that a standard lipid panel will measure the amount of HDL cholesterol (HDL-C). For decades, raising HDL-C has been the primary target for doctors in treating and preventing heart disease. However, scientists found that almost 50% of people who have a heart attack have normal cholesterol levels [R, R, R]. 

This has led researchers to look beyond HDL-C -- into HDL particles, which may better predict the risk of heart disease. 

To help visualize the difference between HDL-C and HDL particles, you can think of HDL particles as cars on a highway (blood vessel) and cholesterol molecules as the passengers. HDL-C is a measure of the number of passengers on the roads, while the number and size of HDL particles represents the number and the size of the cars [R].  

Cholesterol transported by HDL is known as “good cholesterol” because HDL particles help remove it d from cells and artery walls, which helps prevent, reduce, and even reverse hardening of the arteries (atherosclerosis) and accumulation of fatty plaques [R, R]. 

Large HDL particles are believed to be more protective against heart disease. Research suggests that large HDL particles remove cholesterol from artery walls more efficiently. They are also better at preventing blood clots and decreasing inflammation. Also, larger HDL particles are linked to lower LDL particles in the blood (there are particles that carry "bad cholesterol"), so their heart-protective properties may also be related to reduced LDL. Many studies have found that people with high concentrations of larger HDL particles are at lower risk for heart disease [R, R, R].

This test measures how much of your blood volume is made of red blood cells.

Because red blood cells carry oxygen from the lungs to the rest of the body, hematocrit (HCT) shows how well the body can deliver oxygen to your tissues [R].

Your doctor will interpret a rise or drop in hematocrit together with other tests, such as hemoglobin, RBC, and red blood cell indices.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of hemoglobin in your blood. 

Hemoglobin is a protein found in red blood cells that transports oxygen from the lungs to the rest of the body. It contains the mineral iron, which helps it carry oxygen. After the oxygen is used, hemoglobin also carries carbon dioxide back to the lungs where it is exhaled [R].

Hemoglobin levels are used to help diagnose anemia (decreased amount of red blood cells) and polycythemia (increased production of red blood cells).

Both low and high hemoglobin levels can impact your health. They both decrease the oxygen supply to the tissues, although by different mechanisms. High hemoglobin is further associated with an increased risk of high blood pressure and blood clots [R, R, R, R, R, R].

A hemoglobin test is usually done as a part of a complete blood count (CBC), which also looks at other properties of your red blood cells. Your doctor will interpret a rise or drop in hemoglobin together with other tests, such as RBC, hematocrit, and red blood cell indices.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

HbA1c is a measure of your 3-month average blood sugar levels. 

When circulating in the blood, glucose (blood sugar) sticks to hemoglobin found inside red blood cells and forms glycated hemoglobin (HbA1c). The higher your blood sugar, the more HbA1c you'll have in the blood. Usually, HbA1c comprises approximately 5% of a normal adult’s hemoglobin [R].

Because red blood cells that carry hemoglobin live for approximately 3 months, HbA1c can be used as a measure of average blood sugar levels over the past 3 months [R, R].

HbA1c is an important test that can be used to both diagnose and monitor diabetes. 

According to the American Diabetes Association, screening for diabetes is recommended in people over 45 (every 3 years), or at any age if you have certain risk factors, including [R]:

• Being overweight, obese, or physically inactive
• Having a close (first or second-degree) relative with diabetes
• Belonging to a certain race/ethnic group (Native Americans, African-Americans, Hispanic Americans, Asians/South Pacific Islanders)
• Having signs of insulin resistance or conditions associated with insulin resistance, such as high blood pressure (hypertension), low good cholesterol and/or high triglycerides (dyslipidemia), and polycystic ovary syndrome
• Having had diabetes in pregnancy (gestational diabetes)

HbA1c is more convenient than glucose because, unlike glucose, it doesn't require fasting before testing and there is no large day-to-day variation in HbA1c levels. However, some health conditions that affect red blood cells and hemoglobin (e.g., anemia) can falsely increase or decrease HbA1c levels [R].

This test measures the levels of the amino acid homocysteine. 

Homocysteine is a sulfur-containing amino acid that the body produces from another amino acid, called methionine. It's usually found in very small amounts in your body. That’s because our bodies convert it efficiently into other products with the aid of B vitamins. Higher homocysteine levels can signal a deficiency of these vitamins [R].

Apart from vitamin deficiency, higher homocysteine levels have been previously linked to heart disease, cognitive dysfunction, and dementia [R, R, R].

However, newer and larger studies suggest that homocysteine may not be a risk factor for heart disease. That is why the American Heart Association doesn’t recommend routine testing of homocysteine [R, R].

Your doctor may order a homocysteine test to:

• Find out if there is vitamin B12, folate, or vitamin B6 deficiency
• Help diagnose homocystinuria, a rare genetic disorder

Ranges and results may slightly vary from lab to lab, due to differences in equipment, techniques, and chemicals used.

A high-protein meal can significantly increase homocysteine levels. Therefore, you should fast throughout the night before your blood test to ensure the most accurate results [R].

 

Genetically higher homocysteine levels may play a role in:

• Schizophrenia [R, R]
• Stomach cancer [R, R]
• Decreased kidney function and kidney disease [R, R]
• High cholesterol [R]
• Blood vessel problems in the brain [R, R, R, R, R]

They may also play a role in the following conditions, but the evidence is weaker:

• Blood clotting issues (venous thrombosis) [R]
• Obesity [R]
• High blood pressure [R]

On the other hand, homocysteine may not have a causal role in heart disease [R, R, R, R, R, R].

The link between homocysteine and conditions like diabetes, Alzheimer’s disease, and stroke is still unclear [R, R, R, R, R, R].

This test measures the percentage of granulocytes in your blood that are still immature. 

Granulocytes are white blood cells that contain small particles (granules) with enzymes, that when released into the bloodstream, kill bacteria, viruses, and fungal cells [R, R].

Immature granulocytes are normally located in the bone marrow but only make it into the blood once they are mature. Under normal conditions, the immature granulocyte percentage in our blood is less than 1% [R, R]. 

Immature granulocyte levels increase rapidly during infections, inflammation, or some types of cancer [R, R]. 

Your doctor may use this test, along with other tests such as the white blood cell count and CRP, to check for infections and estimate their severity [R].

This test measures the amount of granulocytes in your blood that are still immature. 

Granulocytes are white blood cells that contain small particles (granules) with enzymes, that when released into the bloodstream, kill bacteria, viruses, and fungal cells [R, R].

Immature granulocytes are normally located in the bone marrow but only make it into the blood once they are mature. Under normal conditions, the immature granulocyte percentage in our blood is less than 1% [R, R]. 

Immature granulocyte levels increase rapidly during infections, inflammation, or some types of cancer [R, R]. 

Your doctor may use this test, along with other tests such as the white blood cell count and CRP, to check for infections and estimate their severity [R].

This test measures your insulin levels after at least 8 hours of fasting.

Insulin is a hormone produced in the pancreas. When you eat, carbs are broken down into glucose or blood sugar. The rise in blood sugar triggers insulin release. Insulin helps move glucose from the blood into the fat tissue, muscles, and liver [R, R]. Insulin also helps build proteins and fat [R, R].

Your doctor may order this test to:

• check for insulin resistance
• help determine the cause of low blood sugar (hypoglycemia)
• check how your beta cells in the pancreas are working
• help diagnose an insulin-producing tumor in the pancreas
• help determine when a person with type 2 diabetes needs to start taking insulin

This test measures the amount of interleukin-12 (IL-12) in your blood.

IL-12 is a cytokine, a type of protein important for signaling in the immune system. It plays a crucial role in the activities of the immune system by promoting cellular immunity and initiating inflammatory responses. Produced primarily by dendritic cells and macrophages in response to antigens or infections, IL-12 is vital for the defense against intracellular pathogens and for anti-tumor immunity [R].

IL-12 has several important functions, such as [R]:

• T cell activation
• Inflammation in autoimmune diseases

IL-12 supplementation is being explored for its potential in cancer immunotherapy. IL-12 blockade may help in diseases characterized by excessive inflammation, such as certain autoimmune disorders, like psoriasis and Crohn’s disease [R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal. 

This test measures the amount of iron in your blood.

Iron (Fe) is a metal that plays an essential role in the body. Iron is needed for [R, R, R, R, R, R]: 

• Red blood cell production
• Oxygen and carbon dioxide transport in the blood (as part of hemoglobin)
• Oxygen transport and storage in muscles (as part of myoglobin)
• Energy production in the heart and muscles
• Brain development and normal brain function
• Immune system development and immune response
• Resistance to infections
• Production and degradation of DNA

However, blood iron alone is not a great measure of how much iron there is in the body because it fluctuates daily. For example, it can increase after you ingest iron-rich foods. It can also stay normal, even when your body's iron reserves are seriously depleted [R, R].

Instead, ferritin, transferrin, and total iron binding capacity (TIBC) measurements can be better indicators of your overall iron status [R, R]. Your doctor may order several of these tests in conjunction with an iron test and then interpret the results together to help diagnose and/or monitor iron deficiency or iron overload.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of LDL-cholesterol, also known as "bad" cholesterol, in your blood.

LDL-cholesterol is cholesterol bound to low-density lipoprotein (LDL) particles. Lipoprotein particles transport cholesterol in the bloodstream much like cars transport passengers [R].

LDL- cholesterol is considered the “bad” cholesterol because it deposits in blood vessels. Cholesterol can penetrate arterial walls where it combines with oxygen (oxidizes). This is a key step in the development of the hardening of the arteries and heart disease [R, R].

High LDL cholesterol is considered a strong risk factor for developing heart disease [R, R].

This test measures the amount of medium-sized LDL particles in the blood. 

A standard lipid panel will measure the amount of LDL cholesterol (LDL-C). Reducing the amount of LDL-C has been the primary target for doctors in treating and preventing heart disease. However, scientists found that almost 50% of people who have a heart attack have normal LDL-C levels [R, R, R]. 

This has led researchers to look beyond LDL-C -- into the size of LDL particles, which may better predict the risk of heart disease [R, R, R]. 

When it comes to LDL particles, size matters -- and the bigger the better. 

Research suggests that small and medium LDL particles more easily go into blood vessel walls, where they deposit plaque, while larger particles bounce off blood vessel walls harmlessly. That's why small and medium LDL particles are associated with a greater risk of hardening of the arteries (atherosclerosis), heart disease, and diabetes [R, R, R].

This test measures the amount of LDL particles in your blood. 

A standard lipid panel will measure the amount of LDL cholesterol (LDL-C). Reducing LDL-C has been the main target for treating and preventing heart disease. However, scientists found that almost 50% of people who have heart attacks have normal LDL-C levels [R, R, R]. 

This has led researchers to look beyond LDL-C -- into LDL particles, which may better predict the risk of heart disease [R, R, R].

To help visualize the difference between LDL-C and LDL particles, you can think of LDL particles as cars on a highway (blood vessel) and cholesterol molecules as the passengers. LDL-C is a measure of the number of passengers on the roads, while the LDL particles represent the number of cars [R].  

Studies suggest that the number of LDL particles may be better at predicting heart disease than LDL cholesterol [R, R, R].

This test measures the peak size of LDL particles in the blood. When it comes to LDL particles, size matters -- and the bigger the better. A higher LDL peak size has been associated with better health outcomes. 

Research suggests that small LDL particles more easily go into blood vessel walls, where they deposit plaque, while larger particles bounce off blood vessel walls harmlessly. That's why while small LDL particles carry less cholesterol than the larger particle sizes, they are associated with a greater risk of hardening of the arteries (atherosclerosis), heart disease, and diabetes [R, R, R, R, R, R, R, R].

This test measures the amount of small LDL particles in the blood. 

When it comes to LDL particles, size matters -- and the bigger the better. 

Research suggests that small LDL particles more easily go into blood vessel walls, where they deposit as plaque, while larger particles bounce off blood vessel walls harmlessly. That's why while small LDL particles carry less cholesterol than the larger particle sizes, they are associated with a greater risk of hardening of the arteries (atherosclerosis), heart disease, and diabetes [R, R, R, R, R, R, R, R, R].

This test looks at the size of LDL particles in your blood.

You may already know that a standard lipid panel will measure the amount of LDL cholesterol (LDL-C). For decades, reducing LDL-C has been the primary target for doctors in treating and preventing heart disease. However, scientists found that almost 50% of people who have a heart attack have normal LDL-C levels [R, R, R]. 

This has led researchers to look beyond LDL-C -- into LDL particles, which may better predict the risk of heart disease [R, R, R].

To help visualize the difference between LDL-C and LDL particles, you can think of LDL particles as cars on a highway (blood vessel) and cholesterol molecules as the passengers. LDL-C is a measure of the number of passengers on the roads, while the number and size of LDL particles represents the number and the size of the cars [R].  

When it comes to LDL particles, size matters -- and the bigger the better [R]. 

Research suggests that smaller LDL particles more easily end up in blood vessel walls, where they deposit plaque, while larger particles bounce off blood vessel walls harmlessly. That's why while smaller LDL particles carry less cholesterol than the larger particle sizes, they are associated with a greater risk of hardening of the arteries (atherosclerosis), heart disease, and diabetes [R, R, R, R, R, R, R, R].

This test measures the LDL-C/APOB ratio in your blood.

The LDL-C/ApoB ratio compares:

• The concentration of low-density lipoprotein (LDL) cholesterol (LDL-C)
• The number of Apolipoprotein B (apoB) -containing lipoproteins

This ratio may be a better measure of heart disease risk than LDL-C and ApoB alone [R].

• LDL-C is the set of lipoprotein particles that transport cholesterol in the bloodstream, similar to how cars transport passengers [R].

• ApoB is a large protein that acts as the structural backbone for LDL-C. Each LDL-C molecule contains one molecule of apoB. So, measuring apoB gives an indication of the number of LDL particles [R, R]. 

A high LDL-C but low ApoB results in a higher LDL-C/ApoB ratio. This suggests that there are fewer LDL particles, but they are larger and cholesterol-rich. In contrast, a lower ratio indicates a higher number of small, dense LDL particles [R]. 

Small dense LDL particles are considered more harmful as they deposit on artery walls and contribute to plaque formation. Hence, having a low LDL-C/ApoB ratio is undesirable [R].

Especially for those 65 or older, the LDL-C/ApoB ratio can help predict the risk for [R, R]:

• Heart attack
• Stroke
• Heart disease mortality

For accurate heart disease risk assessment and management, it's essential to consider the LDL-C/ApoB ratio alongside other risk factors such as family history, blood pressure, and lifestyle habits.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test calculates the ratio of LDL-C and HDL-C levels in your blood.

This ratio is an indicator of heart disease [R].

In general, the smaller the number the better, as this means that your HDL-C (“good cholesterol”) is high compared to your LDL-C ("bad cholesterol") levels [R].

This test measures the amount of luteinizing hormone (LH) in your blood.  

Luteinizing hormone (LH) is a hormone made by the pituitary gland that plays a key role in reproductive function in both men and women.

LH levels are controlled by the hypothalamus, pituitary gland, and hormones made by the ovaries and testicles.

In men, LH signals the testes to produce testosterone. Testosterone, in turn, stimulates sperm production [R].

In women, LH carries out different roles in different stages of the menstrual cycle. During the first two weeks of the cycle, LH signals the ovaries to produce the female sex hormone estradiol. Then a rapid “surge” in LH levels causes the ovaries to release an egg (ovulation). In the last stages of the cycle, LH stimulates the production of progesterone, which is required to support the early stages of pregnancy, if fertilization occurs [R].

LH levels increase in women once they reach menopause.

Your doctor may order this test if you are:

• Having difficulty getting pregnant
• Having irregular menstrual periods
• Going through menopause
• Having low testosterone or low sexual drive
• Having symptoms of pituitary or hypothalamic disorders

LP-IR score is an estimate of insulin resistance [R].

It combines six measures, each associated with insulin resistance and type 2 diabetes [R]:

• Large VLDL-P
• VLDL size
• Small LDL-P
• LDL size
• Large HDL-P
• HDL size

Several studies have found that higher LP-IR increases the risk of developing type 2 diabetes, even in the absence of other traditional risk factors [R, R, R, R].

In addition, measuring LP-IR presents a simple alternative to measuring insulin resistance directly, which is difficult and complicated [R]. 

However, LP-IR is still a relatively new score, and more studies are needed before it's widely accepted into day-today medical practice.

This test measures the amount of lactate dehydrogenase in your blood.

Lactate dehydrogenase (also known as lactic dehydrogenase, LDH, or LD) is an enzyme involved in energy production. There are 5 different forms of LDH, and they are present in most tissues. LDH levels normally increase after tissue breakdown, so LDH tests are normally used as markers of heart attacks, lung diseases, and muscle damage. However, since LDH is found in many different muscles, it cannot be used to diagnose any specific disease and must be used in conjunction with other tests [R, R].

This test looks at how many large VLDL particles you have in the blood.

A standard lipid panel measures the amount of different types of cholesterol in the blood. For decades, reducing bad cholesterol has been the primary target for doctors in treating and preventing heart disease. However, scientists found that almost 50% of people who have a heart attack have normal cholesterol levels [R, R, R]. 

This has led researchers to look beyond cholesterol, into LDL, HDL, and VLDL particles, which may better predict the risk of heart disease [R, R, R].

To help visualize the difference between VLDL-cholesterol (VLDL-C) and VLDL particles, you can think of VLDL particles as cars on a highway (blood vessel) and cholesterol molecules as the passengers. VLDL-C is a measure of the number of passengers on the roads, while the number and size of VLDL particles represents the number and the size of the cars [R].  

A higher number of large VLDL particles has been associated with metabolic disturbances and a higher risk of heart disease [R].

This test measures the amount of lead in your blood.

Lead is a heavy metal that has been used by many manufacturers to make paint, ceramics, plastics, automobiles, and even cosmetics [R, R].

Lead can build up in the body over months or years, and can be toxic even in smaller amounts. It is extremely harmful to the body, and can cause serious permanent damage to the brain, kidneys, heart, and reproductive system [R, R].

For these reasons, lead use has been discontinued in common commercial items in the US and many other countries. However, it is still sometimes used in car repair, battery manufacturing and recycling, and smelting. Lead can also be found in the soil or in older buildings, where lead-based paint had been used. 

People who work with batteries, in auto repair shops, those who do home renovations, or with stained glass or making jewelry are at a higher risk of lead exposure.

There is no treatment for lead poisoning, but you can take some precautions to prevent it from happening, including doing occasional testing if you're exposed to lead at work.

This test measures the amount of leptin in your blood. 

Known as the “satiety hormone,” leptin is a hormone that is mainly produced by fat cells [R].

When you eat enough food, leptin is released into the bloodstream, where it travels to the brain, signaling that you're full and that you can burn calories at a normal rate [R, R, R].

It also plays an important role in reproductive, immune, thyroid, and adrenal gland function as well as growth hormone production [R].

Circulating leptin levels are directly proportional to the amount of body fat and they change depending on food intake [R, R, R].

Factors that affect leptin levels include: 

• Time of day: Leptin levels are higher at night than during the day [R].
• Sex: Women have higher leptin levels than men [R].

This test is not routinely ordered. It's mainly used for research and its usefulness in medical settings is not yet established. 

A leptin test may be ordered for overweight/obese individuals, especially if there is a family history of obesity. It can also be ordered for an obese person who has symptoms of frequent, persistent hunger to detect a leptin deficiency or excess.

Sometimes, it is used with other tests, such as a thyroid panel, glucose, cholesterol, and insulin, to determine the health status of an overweight/obese person and detect underlying conditions that may be contributing to or worsening their condition.

This test measures the amount of linoleic acid in your blood.

Linoleic acid is the most highly consumed omega-6 fatty acid. It is an essential fatty acid because humans cannot produce it and should get it from food [R].

Linoleic acid supports [R, R]:

• Energy production
• Skin health
• Heart Health 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the levels of pancreatic lipase in the blood.

Lipases are enzymes that break down fats (lipids) into smaller molecules [R]. They are important for the digestion, transport, and use of dietary lipids (fats, oils, triglycerides). 

There are many different kinds of lipases. Pancreatic lipase is the main one. It is produced in the pancreas -- the same gland that makes insulin. After you eat, the pancreas releases pancreatic lipase into your digestive tract, where this enzyme breaks down fat (triglycerides) [R].

Not much of the enzyme makes it into the blood under normal conditions. But when the pancreas is inflamed or injured, it releases more lipase than usual. 

Doctors may order a lipase test if they suspect an inflammation of the pancreas (pancreatitis). Pancreatitis is associated with the following symptoms [R, R]:

• Moderate to severe abdominal pain/back pain
• Nausea
• Vomiting
• Loss of appetite
• Oily/fatty stools

You may be at risk for pancreatitis if you:

• Have high triglyceride levels in your blood [R, R, R]
• Drink too much alcohol [R]
• Have been diagnosed with gallbladder stones (which may block the flow from the pancreas to the intestines) [R, R, R]
• Have a family history of pancreatitis [R]
• Have type 2 diabetes [R]
• Are overweight/obese [R, R, R] - this increases the severity of the disease

This test measures the amount of lipoprotein(a) in the blood and helps your doctor determine your heart disease risk.

Lipoproteins are a mesh of proteins and fats that help carry cholesterol in the blood. Examples include low-density lipoprotein (LDL), which carries “bad cholesterol” and high-density lipoprotein (HDL), which carries “good cholesterol” [R].

Lipoprotein(a), or Lp(a) is a type of LDL. Lp(a) is made in the liver and carries fats and other lipids such as cholesterol around the body [R, R].

The exact function of Lp(a) is still being researched. Researchers think Lp(a) is involved in wound healing, tissue repair, immune response, and inflammation. However low or even undetectable Lp(a) levels are common and do not appear to have any negative health effects [R, R, R].

What we do know is that high levels pose a health risk. In particular, higher Lp(a) levels have been associated with heart disease and stroke [R, R, R, R, R, R].

Lp(a) levels are largely determined by genetics and remain more or less stable throughout your life. However, some conditions can increase Lp(a), including hormonal imbalances, inflammatory diseases, metabolic issues, and kidney disease [R, R, R].

Although largely genetic, some newer studies suggest that certain lifestyle and dietary interventions may help slightly reduce lipoprotein(a) levels [R, R, R].

The Lp(a) test is not a routinely ordered test. Your doctor will usually order it if you have other risk factors for heart disease, such as [R]:

• Heart disease runs in your family
• You have a genetic condition that causes high cholesterol levels (familial hypercholesterolemia)
• Your heart disease is worsening despite treatment with statins

Typically, Lp(a) test is only done once, because it’s pretty constant across your lifetime. On occasion, your doctor may order a second Lp(a) test to confirm the first one:

• If it was measured when you were ill
• After menopause, because Lp(a) levels increase as estrogen levels drop

This test looks at the activity of Lp-PLA2 in your blood. 

Lp-PLA2 is an enzyme produced by inflammatory cells (e.g., macrophages) in blood vessels. It is involved in the inflammation of blood vessels and the hardening of the arteries (atherosclerosis) [R].

Your doctor may order an Lp-PLA2 test to help determine your risk of developing heart disease or stroke. The test is typically ordered for people who are already at a moderate to high risk for developing heart disease due to risk factors like [R, R]:

• Diabetes
• Metabolic syndrome
• Smoking
• Advanced age (65 and older)

Unlike hs-CRP, which is also used to assess chronic inflammation as it relates to heart disease, the Lp-PLA2 test is not affected by other inflammatory conditions, like colds and infections. Lp-PLA2 may serve as a more useful biomarker for the risk of heart disease or stroke [R].

Several lines of evidence suggest that oxidation of LDL plays a critical step in the development and progression of atherosclerosis.

Lp-PLA2 participates in the breakdown of oxidized LDL in the vascular wall by breaking down the oxidized phospholipid. Higher levels can, therefore, also correlate with higher oxidized LDL.

When it breaks down the oxidized phospholipid, it produces lysophosphatidylcholine and oxidized free fatty acids, both of which are potent pro-inflammatory products that contribute to the formation of atherosclerotic plaques [R].

Lp-PLA2 can be separated into enzyme mass or concentration and activity. Both are associated with very low-density lipoprotein (VLDL), LDL, and high-density lipoprotein (HDL). Lp-PLA2 concentration also correlates with triglyceride and total cholesterol levels [R].

This test looks at the percentage of white blood cells that are lymphocytes.

Lymphocytes are white blood cells important for both innate (nonspecific) and adaptive (long-lasting and specific) immune responses [R].

There are three main types of lymphocytes: B cells, T cells, and natural killer (NK) cells [R, R].

• B cells produce antibodies that attack freely circulating foreign bodies, such as bacteria and viruses
• T cells destroy the body's cells, which have been infected by viruses or transformed into cancer cells. They also direct the responses of other immune cells and prevent immune responses against healthy cells (autoimmunity)
• NK cells kill cancer cells and cells infected by viruses

Lymphocyte levels can vary with age, gender, genetics, and lifestyle factors. They can both increase or decrease in response to infection. Your doctor will interpret your results, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test looks at the lymphocyte count in your blood.

Lymphocytes are white blood cells important for both innate (nonspecific) and adaptive (long-lasting and specific) immune responses [R].

There are three main types of lymphocytes: B cells, T cells, and natural killer (NK) cells [R, R].

• B cells produce antibodies that attack freely circulating foreign bodies, such as bacteria and viruses
• T cells destroy the body's cells, which have been infected by viruses or transformed into cancer cells. They also direct the responses of other immune cells and prevent immune responses against healthy cells (autoimmunity)
• NK cells kill cancer cells and cells infected by viruses

Lymphocyte levels can vary with age, gender, genetics, and lifestyle factors. They can both increase or decrease in response to infection. Your doctor will interpret your results, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the average amount of hemoglobin in your red blood cells.

Hemoglobin is the protein that binds oxygen, which allows your blood to transport oxygen throughout your body.

Mean corpuscular hemoglobin (MCH) can be used to help diagnose different types of anemia [R].

An MCH test is usually done as a part of a complete blood count (CBC), which also looks at other properties of your red blood cells. Your doctor will interpret a rise or drop in the MCH together with other tests, such as RBC, hemoglobin, hematocrit, RDW, etc.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the mean corpuscular hemoglobin concentration (MCHC) in your blood.

MCHC is the average amount of hemoglobin per red blood cell, relative to the size of the cell. In other words, it tells you what percentage of your blood cells are made up of hemoglobin, the protein that helps transport oxygen in the blood. It is calculated from hemoglobin and your red blood cell count.

Mean corpuscular hemoglobin concentration (MCHC) can be used to help diagnose different types of anemia [R].

Decreased MCHC causes hypochromia (“hypo-” = low, “chromia” = color), which makes the red blood cells paler. Meanwhile, increased MCHC causes red blood cells to become darker, also known as hyperchromia [R, R].

An MCHC test is usually done as a part of a complete blood count (CBC), which also looks at other properties of your red blood cells. Your doctor will interpret a rise or drop in the MCHC together with other tests, such as RBC, hemoglobin, hematocrit, RDW, etc.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal

This test measures the average size (volume) of red blood cells in your body.

Blood cells that are produced when the body lacks certain vitamins in minerals are often too big or too small. If you have anemia, your MCV gives additional information about the cause [R].

Along with other red blood cell indices, MCV is used to help diagnose many conditions, including various types of anemia, thalassemia, and liver disease [R].

An MCV test is usually done as a part of a complete blood count (CBC), which also looks at other properties of your red blood cells. Your doctor will interpret a rise or drop in the MCV together with other tests, such as RBC, hemoglobin, hematocrit, RDW, etc.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the average size of the platelets found in your blood. 

Platelets are tiny cell fragments essential for normal blood clotting. They are formed in the bone marrow and are released into circulation [R].

Platelets keep us from bleeding excessively when we are injured. When you cut yourself, for example, platelets stick together to plug the injury site. Other clotting factors are then recruited to the scene to prevent further bleeding [R].

Platelet size is larger when the body is producing an increased number of platelets, so an MPV test can be used to check for issues with platelet production in the bone marrow or platelet destruction [R].

An MPV test result can't be used to diagnose anything on its own. Your doctor will interpret the test in conjunction with your medical history and other test results, such as platelet count.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of magnesium in your blood. 

Magnesium is the 4th most abundant mineral in the body. It is required for more than 300 different bodily processes [R, R].

Magnesium:

• helps our cells produce energy
• is needed for our nerve cells and brain to function properly
• makes our bones stronger
• is essential for muscles -- including the heart -- function
• is important for the immune system
• helps adjust the levels of glucose and insulin in the blood

Magnesium cannot be produced in the body and must be consumed in sufficient amounts from one’s diet [R].

Magnesium is primarily absorbed through the gut. However, the kidneys are the main regulator of magnesium levels and activity throughout the body. They tell the digestive system to absorb more or less magnesium from digested food according to the body’s current levels [R, R, R, R, R, R, R].

The older you get, the less efficiently your body holds onto magnesium. Older people are more likely to have low magnesium [R, R, R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test is used to determine magnesium levels in red blood cells.  

Magnesium is the 4th most abundant mineral in the body [R]. It is required for more than 300 different bodily processes [R].

Magnesium:

• helps our cells produce energy
• is needed for our nerve cells and brain to function properly
• makes our bones stronger
• is essential for muscles -- including the heart -- function
• is important for the immune system 
• helps adjust the levels of glucose and insulin in the blood

Magnesium cannot be produced in the body, and must be consumed in sufficient amounts from one’s diet [R].

Magnesium is primarily absorbed through the gut. However, the kidneys are the main regulator of magnesium levels and activity throughout the body. They tell the digestive system to absorb more or less magnesium from digested food according to the body’s current levels [R, R, R, R, R, R, R].

The older you get, the less efficiently your body holds onto magnesium. Older people are more likely to have low magnesium [R, R, R].

Normally, in an adult body about 60% of magnesium is in the bone, 20% in the muscles, 19% in other soft tissues and less than 1% in the fluid outside of cells [R].

Because only 1% of total magnesium in the body is located outside of cells, blood levels do not reflect magnesium levels inside of the cells. RBC magnesium is a more accurate measurement of magnesium levels in tissues and a better representation of total magnesium stores in the body [R, R, R].

Studies suggest that the RBC magnesium test can reveal a magnesium deficiency earlier than a standard magnesium blood test.That's because when magnesium levels are low, the body takes magnesium from red blood cells and other tissues like bone and muscles to maintain blood levels [R, R, R].

This test measures the amount of mercury (Hg) in your blood.

Mercury is a type of metal. It does not play any role in the human body and is toxic in higher amounts.

There are three different types of mercury that people can be exposed to:

• Elemental
• Inorganic
• Organic (methylmercury)

Generally, people encounter organic methylmercury the most, because it is present in seafood and freshwater fish and shellfish. 

Elemental or inorganic mercury exposure can result from workplace or environmental exposure, coal burning, or tooth fillings (dental amalgams) [R, R]. 

Normally, most people are only exposed to tiny levels of mercury, which does not cause any health concerns. However, people who are exposed to mercury over a long period of time may develop mercury-related issues, including permanent kidney, nerve, and brain damage [R]. Pregnant or nursing women with high mercury levels can also pass it to their babies [R].

Total blood mercury is a good indicator of methylmercury exposure in people who consume fish. Urine mercury levels, on the other hand, are better indicators of inorganic mercury exposure [R].

This test measures the levels of methylmalonic acid (MMA), a functional indicator of your vitamin B12 status.

Methylmalonic acid is normally produced in very small amounts when you digest protein and fat. It gets broken down by vitamin B12. When there's not enough vitamin B12, MMA builds up, and the levels in the blood increase [R, R].

Methylmalonic acid levels increase in the early stages of vitamin B12 deficiency, when total vitamin B12 levels may still be in the normal range. Therefore, measuring MMA can tell you if you have a mild vitamin B12 deficiency [R].

You may want to test your MMA if you belong to one or more of the following groups that have an increased risk of B12 deficiency:

• Vegans and vegetarians [R, R, R]
• Pregnant and breastfeeding women [R, R]
• Heavy alcohol drinkers [R, R]
• Obese people [R, R]
• People with gut disorders that reduce the absorption of dietary B12 [R, R, R]
• AIDS/HIV patients [R, R]

Elderly people also have an increased risk of B12 deficiency, because the gut becomes less efficient at absorbing nutrients as we age [R, R, R]. However, a blood MMA test is not recommended in older people because levels increase as the kidney function decreases, regardless of vitamin B12 status [R, R].

Also, there is a genetic mutation in people of European ancestry that can increase MMA levels by almost 50% [R].

It's important to know that MMA levels can only indicate B12 deficiency but they reflect neither the severity of symptoms, nor whether a person will progress to full deficiency. It's best if this test is used together with a total vitamin B12 test [R].

This test checks what percentage of your white blood cells are monocytes.

Monocytes are white blood cells that protect against bacterial, viral, and other infections.

Monocytes kill microbes, remove dead cells, and boost the immune response. However, they are also involved in the development of several inflammatory diseases and can contribute to tissue destruction during infection or inflammation [R].

Your doctor will interpret this test, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test looks at your monocyte count.

Monocytes are white blood cells that protect against bacterial, viral, and other infections.

Monocytes kill microbes, remove dead cells, and boost the immune response. However, they are also involved in the development of several inflammatory diseases and can contribute to tissue destruction during infection or inflammation [R].

Your doctor will interpret this test, taking into account your medical history and other test results.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test looks at the percentage of white blood cells that are neutrophils.

Neutrophils are the most abundant white blood cells in the body. They protect you from bacterial, fungal, and other infections and are first-responders at sites of infection and inflammation [R]. 

Like other blood cells, neutrophils are produced in the bone marrow [R, R].

A high neutrophil percentage may signal an infection or inflammation somewhere in the body. Neutrophils also often increase in response to physical or emotional stress. 

A low percentage, on the other hand, can be due to drugs such as chemotherapeutics, or health conditions such as autoimmune issues, nutrient deficiencies, and bone marrow disorders. 

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test looks at your neutrophil count.

Neutrophils are white blood cells that protect you from bacterial, fungal, and other infections [R].

Neutrophils are the most abundant white blood cells in the body. They are first-responders at sites of infection and inflammation [R]. 

Like other blood cells, neutrophils are produced in the bone marrow [R, R].

A high neutrophil count may signal an infection or inflammation somewhere in the body. Neutrophils also often increase in response to physical or emotional stress. 

Low levels, on the other hand, can be due to drugs such as chemotherapeutics, or health conditions such as autoimmune issues, nutrient deficiencies, and bone marrow disorders. 

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

Essentially, this test looks at the total amount of "bad" (LDL + VLDL) cholesterol in your blood.

Non-HDL cholesterol is a measure of all the cholesterol that's carried by LDL and VLDL particles. It's calculated by subtracting your HDL cholesterol, known as "good" cholesterol, from your total cholesterol [R]. 

Non-HDL cholesterol is associated with the risk of heart disease [R, R, R, R, R, R, R, R]. In general, the lower your non-HDL cholesterol, the better.

This test measures the amount of nucleated red blood cells in your blood.

Nucleated RBCs (NRBCs, normoblasts) are immature red blood cells (RBCs) that contain a nucleus [R].

Normally, nucleated RBCs are only found in the bone marrow. Their presence in the blood means there is increased red cell production or bone marrow disease/damage [R].

Nucleated RBCs is a test often requested as a follow-up to abnormal results on a complete blood count (CBC) in order to evaluate blood cell abnormalities. It can also be done when a person has signs and symptoms that point to a condition affecting blood cell production or lifespan. 

NRBC look very similar to white blood cells. It is important to identify nucleated RBCs because their presence can falsely elevate white blood cell (WBC) count, which may interfere with getting appropriate treatment [R].

Your doctor will interpret this test, taking into account your medical history and other test results.

This test measures the percentage of cells that look like white blood cells that are actually NRBC in your blood.

Nucleated RBCs (NRBCs, normoblasts) are immature red blood cells (RBCs) that contain a nucleus [R].

Normally, nucleated RBCs are only found in the bone marrow. Their presence in the blood means there is increased red cell production or bone marrow disease/damage [R].

Nucleated RBCs is a test often requested as a follow-up to abnormal results on a complete blood count (CBC) in order to evaluate blood cell abnormalities. It can also be done when a person has signs and symptoms that point to a condition affecting blood cell production or lifespan. 

It is important to identify nucleated RBCs because their presence can falsely elevate white blood cell (WBC) count, which may interfere with getting appropriate treatment [R].

Your doctor will interpret this test, taking into account your medical history and other test results.

This test looks at the ratio of omega-6 to omega-3 fatty acids in your blood.

Both omega-3 and omega-6 are important for your health. Omega-6 may be pro-inflammatory, while omega-3 fatty acids are anti-inflammatory. Western diets contain excessive levels of omega-6 but very low levels of omega-3, leading to high omega-6/omega-3 ratios [R].

High omega-6/omega-3 ratios are linked to obesity, heart disease, and diabetes. Higher omega-3 levels, which lead to low omega-6/omega-3 ratios, have been linked to better health and a lower risk of heart disease [R].

The omega-6/omega-3 ratio is normally used within the fatty acid profile, to assess whether or not you have an increased risk of heart disease.

This test looks at what percentage of total prostate-specific antigen (total PSA) is made of free (unbound) PSA in your blood.

PSA is a protein that is made in the prostate. There are two forms of PSA - bound and free. Bound PSA is bound to other proteins, while free PSA is not bound to anything. Total PSA measures the amount of both bound and free PSA in the blood [R]. 

Total PSA tests are mainly used to screen for prostate cancer. However, since other things can influence total PSA levels, they are not specific enough to diagnose prostate cancer and false positive results are common. A false positive result is when the result says you may have a condition or a disease, but in reality, you don't have it.

A free PSA test is often ordered to help your doctor or another healthcare professional decide if you should get a prostate biopsy when your total PSA levels are "within the gray zone" of 4 - 10.0 ng/mL or ug/L. Some doctors may also order this test with lower total PSA levels [R, R, R]. 

Prostate tumors normally produce bound PSA, while normal prostate cells produce free PSA. Free PSA tests are used to find the PSA free/total ratio or the % of PSA that is free. A high ratio means that you likely do not need a prostate biopsy [R, R]. However, this test is not 100% reliable [R, R]. Your doctor will interpret this test, taking into account your medical history, signs, symptoms, and other test results. 

Because of the high chance of false positive results, men over 55 should decide whether to undergo periodic PSA-based screening after discussing the potential benefits and harms of screening based on family history, race/ethnicity, medical conditions, etc. with their doctor. Those at a higher risk, such as men with a family history of the disease, may consider beginning testing earlier, at the age of 40-45 [R].

This test is not recommended for men over 70 [R].

Refrain from exercising, ejaculating, or performing any activity that causes pressure on your prostate (riding a bike) before your blood test [R, R].

This test measures the amount of free prostate specific antigen (free PSA) in your blood.

PSA is a protein that is made in the prostate. There are two forms of PSA - bound and free. Bound PSA is bound to other proteins, while free PSA is not bound to anything. Total PSA measures the amount of both bound and free PSA in the blood [R]. 

Total PSA tests are mainly used to screen for prostate cancer. However, since other things can influence total PSA levels, they are not specific enough to diagnose prostate cancer and false positive results are common. A false positive result is when the result says you may have a condition or a disease, but in reality you don't have it.

A free PSA test is often ordered to help your doctor or another healthcare professional decide if you should get a prostate biopsy, when your total PSA levels are "within the gray zone" of 4 - 10.0 ng/mL or ug/L. Some doctors may also order this test with lower total PSA levels [R, R, R]. 

Prostate tumors normally produce bound PSA, while normal prostate cells produce free PSA. Free PSA tests are used to find the PSA free/total ratio or the % of PSA that is free. A high ratio means that you likely do not need a prostate biopsy [R, R].

Because of the high chance of false positive results, men over 55 should decide whether to undergo periodic PSA-based screening after discussing potential benefits and harms of screening on the basis of family history, race/ethnicity, medical conditions, etc. with their doctor. Those at a higher risk, such as men with a family history of the disease, may consider to begin testing earlier, at the age of 40 - 45 [R].

This test is not recommended for men over 70 [R].

Different laboratories may have different cutoff values for this test. Don't panic if your results are not within the normal range. Your doctor will interpret this test, taking into account your medical history, signs, symptoms, and other tests results. 

Refrain from exercising, ejaculating, or performing any activity that causes pressure on your prostate (riding a bike) before your blood test [R, R].

This test measures the total amount of prostate-specific antigen (PSA) in your blood.

PSA is a protein that is made in the prostate. There are two forms of PSA - bound and free. Bound PSA is bound to other proteins, while free PSA is not bound to anything. Total PSA measures the amount of both bound and free PSA in the blood [R]. 

PSA tests are mainly used to screen for or to monitor prostate cancer. 

However, since other things can influence PSA levels, a total PSA blood test is not specific enough to diagnose prostate cancer and false positive results are common. A false positive result is when the result says you may have a condition or a disease, but in reality, you don't have it.

PSA levels increase with age, and African Americans tend to have higher PSA levels. Levels can also be high if someone has an enlarged prostate (benign prostatic hyperplasia) or prostate infection or inflammation (prostatitis) [R, R, R]. 

Because of the high chance of false positive results, men over 55 should decide whether to undergo periodic PSA-based screening after discussing the potential benefits and harms of screening based on family history, race/ethnicity, medical conditions, etc. with their doctor. Those at a higher risk, such as men with a family history of the disease, may consider beginning testing earlier, at the age of 40 - 45 [R].

This test is not recommended for men over 70 [R].

A PSA test cannot be used to diagnose cancer. If they suspect prostate cancer, your doctor or another health professional will do a biopsy, collecting a small sample of prostate tissue and looking for abnormal cells under the microscope

If prostate cancer is diagnosed, this test can be used to monitor disease progress (active surveillance or watchful waiting), the effectiveness of the treatment, or to check for cancer recurrence. If that's the case, make sure you are doing your test at the same laboratory each time, so that you and your doctor can reliably compare your results.

Different laboratories may have different cutoff values for this test. Don't panic if your results are not within the normal range. Your doctor will interpret this test, taking into account your medical history, signs, symptoms, and other test results. 

Refrain from exercising, ejaculating, or performing any activity that causes pressure on your prostate (riding a bike) before your blood test [R, R].

This test measures the amount of phosphate (phosphorus) in your blood [R]. 

Phosphorus is the second most abundant mineral in the human body, where it's mainly found in a form called phosphate, which is a phosphorus atom bound to four oxygen atoms [R, R]. 

Phosphorus makes up about 1 percent of an adult's body: 85% of it is found in the bone while the remaining 15% is distributed in cells and tissues throughout the body, where it is mainly used to store energy in the form of ATP [R, R]. 

Phosphorus is crucial for bone health, muscle, and nerve function, cell and DNA structure, and blood acid-base (pH) balance [R].

Phosphorus levels are controlled by the gut, kidneys, and the hormones calcitriol (vitamin D), calcitonin, parathyroid hormone (PTH), and FGF23 [R, R].
 

Since phosphorus is abundant in the diet, deficiency due to low dietary intake is rare. However, it can occur during prolonged starvation or in certain gut conditions that cause malabsorption or diarrhea. 

There are many different health conditions that can decrease or increase phosphate levels. Your doctor will interpret your test, taking into account your medical history, symptoms, and other test results.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the number of platelets in your blood.

A platelet, also called a thrombocyte, is a type of cell that helps blood to clot. Clotting slows down and stops bleeding and helps wounds heal [R, R].

Platelets are made in the bone marrow. They survive in the circulation for about 8-10 days, which is why the bone marrow needs to continually make new ones, to replace old, used ones or those lost through bleeding [R, R].

Apart from wound healing, platelets are also involved in immune system defenses and inflammation [R, R]. 

Impaired platelet function can cause issues with blood clots or prevent proper wound healing [R].

A platelet count can be used to:

• Help diagnose various issues such as bleeding or clotting disorders or bone marrow disease
• Monitor a known underlying health condition
• Monitor treatment with drugs known to affect platelets

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of potassium in your blood.

Potassium is a positive ion that has many important functions in our bodies. It [R, R, R, R]:

• controls blood pressure
• helps balance fluids
• is needed for nerves and muscles to communicate
• helps store nutrients, including glucose, inside of cells 

Potassium is absorbed through the gut and removed by the kidneys through urine [R, R]. 

Testing potassium is important for evaluating kidney, heart, and adrenal health.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of potassium in your blood.

Potassium is a positive ion that has many important functions in our bodies. It [R, R, R, R]:

• controls blood pressure
• helps balance fluids
• is needed for nerves and muscles to communicate
• helps store nutrients, including glucose, inside of cells 

Potassium is absorbed through the gut and removed by the kidneys through urine [R, R]. 

Testing potassium is important for evaluating kidney, heart, and adrenal health.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of progesterone in the blood.

Progesterone is a hormone that plays an important role in reproduction. It is made in the ovaries of women and the testes of men. Smaller amounts are also made in the adrenal glands and the brain [R, R]. 

In women, progesterone helps regulate the menstrual cycle and helps prepare the body for pregnancy. In men, progesterone is involved in the development of sperm [R, R].

However, research suggests that progesterone may be more than just a sex hormone. Among other potential functions, it may also protect brain cells from injury and may aid the activity of neurotransmitters [R, R, R].

A progesterone blood test is most commonly used to help monitor a woman’s health during pregnancy, diagnose a failing pregnancy, determine the cause of infertility, or diagnose the cause of abnormal uterine bleeding [R].

In order to accurately interpret progesterone results, women need to know at what point they are in their menstrual cycle (period) or pregnancy. Progesterone levels normally rise and fall over the course of your cycle. In pregnancy, progesterone levels also normally rise as the pregnancy progresses [R, R].

Most men do not normally get their progesterone levels tested unless they are suspected to have an adrenal disease, such as congenital adrenal hyperplasia (CAH). CAH is a group of disorders that limit hormone production in the adrenal glands [R].

This test measures the amount of prolactin in the blood.

Prolactin is a hormone that is produced by the pituitary gland. It plays a key role in fertility and reproduction and stimulates the production of breast milk (lactation). It is also involved in suppressing the stress response, creating and activating new neurons, and stimulating motherly (maternal) behavior [R, R].

Men and non-pregnant women generally have low levels of prolactin. However, women's prolactin levels increase significantly during pregnancy and remain elevated after childbirth. Prolactin stimulates the production of breast milk and helps maintain an adequate supply of milk throughout the breastfeeding period [R].

Your doctor may order a prolactin test to help find the cause of:

• Absent or irregular periods (menstruation) in women
• Spontaneous or abnormal breast milk flow or other unexplained discharge
• Erectile dysfunction or loss of sex drive (libido) in men

This test may also be ordered to screen for pituitary disorders, such as hypopituitarism or pituitary tumors (prolactinomas), or to monitor people taking medications that affect dopamine levels. 

Prolactin levels vary during the day. They increase during sleep and peak in the early morning. Ideally, when doing a prolactin test, you should have your blood sample drawn 3 to 4 hours after waking.

This test measures the total amount of protein in your blood. Total protein includes albumin and globulins.

Proteins play an important role in many biological processes. They help with growth and development, nutrient and hormone transport, and immune function [R].

Normally, albumin makes up for more than half of blood proteins, and the remainder is globulins [R].

Albumin is made in the liver and helps with fat metabolism. It also helps maintain osmotic pressure (prevents fluid from leaking out of blood vessels) and transports hormones, bilirubin, metals, vitamins, minerals, and drugs. 

Globulins include enzymes, antibodies, carriers, and other proteins. Most globulins are made in the liver, although antibodies are produced by white blood cells [R].

Total serum protein is used to check for nutritional deficiencies, digestive problems, and dehydration [R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the number of red blood cells (RBCs), also called erythrocytes, in your blood.

The main function of red blood cells is to supply oxygen to your tissues. Tissues can’t function properly without enough oxygen. Red blood cells bind oxygen in the lungs and deliver it to the tissues, where they then pick up carbon dioxide produced by your cells. They release carbon dioxide in the lungs, bind oxygen, and go through the same process over and over again [R, R].  

RBCs are made within the bone marrow, but many other factors are involved in their production. For example, iron, vitamin B12, folate, and copper are all necessary to make RBCs. So is erythropoietin, a hormone produced by the kidneys [R].

RBCs have a lifetime of approximately 100-120 days, which means that bone marrow needs to continually produce them to replace old ones or those lost because of bleeding [R, R].   

Many different factors can increase or decrease your RBC count, either by affecting the production of blood cells in the bone marrow or by affecting their lifespan in circulation. 

Your doctor may order this test:

• As a part of a routine check-up
• If you have signs or symptoms that suggest a condition that affects RBC production or lifespan
• To monitor a known health condition

An RBC count is usually done as a part of a complete blood count (CBC), which also looks at other properties of your red blood cells. Your doctor will interpret a rise or drop in the RBC count together with other tests, such as hemoglobin, hematocrit, RDW, etc.

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the variation of the size/volume of your red blood cells.

The Red Blood Cell Distribution Width (RDW) test measures how much your blood cells vary in size. 

Low values mean that your blood cells are roughly similar in size, whereas higher values indicate that there is more variety in how big each red blood cell is. Very high levels mean that your blood cells are very unequal in size -- a condition called anisocytosis [R, R].

A high RDW can serve as a sign of several underlying diseases, including [R, R, R, R]:

• Anemias
• Iron and vitamin B12/folate deficiency
• Inflammation
• Injuries and bleeding/hemorrhage
• Liver disease
• Kidney disease
• Hereditary red blood cell disorders, such as thalassemia

However, RDW can still be at a normal level in patients with certain types of anemia (such as aplastic anemia). Therefore, your doctor will keep an eye on your other blood-cell-related test results to fully rule out these possibilities [R].

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures how much your red blood cells vary in size.

Red Blood Cell Distribution Width, expressed as standard deviation (RDW-SD), is normally a part of a complete blood count, which measures your hemoglobin, hematocrit, and red blood cell count [R].

Low values mean that your blood cells are roughly similar in size, whereas higher values indicate that there is more variety in how big each red blood cell is. Very high levels mean that your blood cells are very unequal in size - a condition called anisocytosis [R, R].

A high RDW can serve as a sign of several underlying diseases, including [R, R, R, R]:

• Anemias
• Iron and vitamin B12/folate deficiency
• Inflammation 
• Injuries and bleeding/hemorrhage
• Liver disease
• Kidney disease
• Hereditary red blood cell disorders, such as thalassemia

However, RDW can still be at a normal level in patients with certain types of anemia (such as aplastic anemia). Therefore, your doctor will keep an eye on your other blood-cell-related test results to fully rule out these possibilities [R].

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of rheumatoid factor in your blood.

Rheumatoid factors (RF) are autoantibodies that are produced by the immune system. Autoantibodies attack the body’s own tissues, causing inflammation [R]. 

RFs are mostly found in rheumatoid arthritis patients. However, people with other autoimmune conditions, and even healthy people, may have detectable levels of rheumatoid factor [R]. 

This test is mainly used to help diagnose rheumatoid arthritis [R].

Your doctor will typically order a rheumatoid factor test if you show symptoms of rheumatoid arthritis, such as [R, R]:

• Joint pain, tenderness, redness, and swelling
• Joint stiffness
• Fatigue and weakness
• Slight fever
• Eye or mouth dryness

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal. Always talk with your doctor to learn more about your test results.

This test measures the level of sex hormone-binding globulin (SHBG) in your blood. 

SHBG is a protein made in the liver that binds to sex hormones and helps transport them in the blood. SHBG can also help control the levels of sex hormones (androgens and estrogens) in the body [R, R, R].  

Your doctor may order an SHBG test if your testosterone levels don't match your signs and symptoms, such as [R, R, R]:

• Low sex drive, infertility, erectile dysfunction (in men)
• Infertility, irregular periods, excess facial or body hair (women)

SHBG production is controlled by sex hormones, thyroid hormones, insulin, and dietary factors [R, R, R]. Disturbances in any of these can affect SHBG levels.

This test measures the amount of sodium in your blood.

Sodium is a positive ion and one of the body's main electrolytes, which are minerals we need in relatively large amounts. It plays a vital role in controlling blood pressure, fluid balance, and the acid-base balance in the blood. In addition, sodium is needed for proper nerve and muscle function [R].

Table salt (sodium chloride) and the natural salt content in foods are the main sources of sodium in the diet. Adults need less than 500 mg sodium/day to maintain normal sodium levels in the body. However, 95% of the world’s population consumes between 3 and 6 g/day, which is much more than necessary [R, R]. 

Healthy sodium levels in the body are maintained in a narrow range by [R, R, R]:

• Hormones that increase (natriuretic peptides) or decrease (aldosterone) kidney excretion of sodium through urine
• Hormones that prevent the loss of fluids together with sodium (antidiuretic hormone)
• Thirst. Normally, even a very small (2–3%) increase in blood sodium induces thirst, and sodium levels go back down to normal once the person drinks water 

Dietary sodium deficiency is extremely rare, even among people on very low-sodium diets. Sodium levels may fall below normal under extreme conditions of heavy and continued sweating, or in cases of heavy injury, chronic diarrhea, or kidney disease where the body is unable to hold onto sodium [R, R].

Blood sodium can increase above normal when people don't drink enough water or have an excessive salt intake. It can also increase due to health issues such as kidney disease. Elevated sodium is more common in the elderly, because of a decline in kidney function and a lower intake of liquids [R, R, R]. 

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test compares your urine density to the density of water.

Urine-specific gravity is a fast, simple, and inexpensive indicator of your hydration status and kidney health since it measures the density of salts, minerals, and other compounds eliminated through urine [R, R, R].  

Urine that is too dense or concentrated may mean you are dehydrated. Urine that's diluted or not dense enough may mean that your kidneys are not functioning properly or that you have a condition called diabetes insipidus [R, R]. 

However, this test is not specific. Your doctor will interpret your results in conjunction with your medical history and other test results.

This test measures the amount of reverse triiodothyronine (reverse T3 or rT3) in your blood.

Reverse T3 (rT3) is very similar to regular T3. However, unlike T3, it is not active in the body. RT3 is made from T4 by an enzyme called deiodinase.  

Only 2.5% of reverse T3 is made by the thyroid gland. The other 97.5% is made by other tissues around the body [R].

It was originally believed that reverse T3 was a byproduct of T4 with little activity or function in the body. However, now we know that reverse T3 mainly serves to counterbalance the effects of too much T3. It also may help the body fight viruses and is crucial to brain development. Interestingly, fetuses have 15x the amount of circulating reverse T3 compared to adults [R, R, R].

Levels of reverse T3 are often elevated in critical illnesses such as cancer, stroke, and trauma [R, R].

Although TSH is often used to determine thyroid function, some researchers argue that the ratio of T3 to reverse T3 may be a better indicator [R].

This test measures the total (free + protein bound) T3 in the blood.

There are two major thyroid hormones, triiodothyronine (T3) and thyroxine (T4). The thyroid gland produces 10-15% of T3, but the rest of T3 is made from T4 in the liver, kidneys, central nervous system, pituitary gland, and muscles [R, R, R].

T3 is over 4 times more powerful than T4 and it is responsible for controlling the usage of energy (metabolic rate) [R, R]. 

Most of the T3 in the blood is bound to protein and only a small percentage (~0.5%) is free and active in the body. This test measures both forms of T3 together [R].

Total T3 is often measured to check if the thyroid is working normally and to help diagnose hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid) [R]. 

Your doctor may also order a total T3 test to monitor the effectiveness of therapy [R].

T3 uptake is an indirect measure of TBG (thyroid binding globulin) binding capacity, or how much TBG is available to bind to thyroid hormones [R]. 

T3 uptake is used to detect low or high levels of TBG and its binding capacity in order to determine the cause of low or high total thyroxine (T4) levels. It is measured in addition to total T4, when total T4 levels are abnormally high or low.

This test uses resin which competes with TBG for binding T3, which is why this test is also sometimes referred to as resin uptake.

High T4 levels will decrease T3 uptake by TBG, because more of TBG is being bound to T4. In turn, T3 uptake will increase by the resin. Similarly, low levels of TBG will result in more T3 binding to the resin, increasing T3 uptake [R]. 

T3 uptake can be used to calculate the free T4 index (FT4I), along with total T4 levels. However, now that it’s possible to directly measure free T4 and TBG, this test is becoming obsolete. 

This test measures the amount of free thyroid hormone T3 (triiodothyronine) in the blood.

Most of the T3 that is made by the thyroid and released in the bloodstream is attached to proteins that transport T3 around. When T3 is attached to proteins, it's not active. Only a small percentage (0.5%) of T3 that is not attached to proteins is active in the body. This is referred to as free T3 [R].

Thyroid hormones play critical roles in growth and development (especially the brain), regulating cholesterol levels, energy production, and insulin sensitivity [R].

Free T3 levels are usually normal in people diagnosed with hypothyroidism. Other thyroid tests like TSH and free T4 levels are also usually needed for your doctor to make an accurate diagnosis [R]. 

Free T3 is therefore mostly used to monitor hyperthyroidism when TSH levels are low [R].

This test measures the total (free + protein bound) T4 in the blood.

There are two major thyroid hormones, triiodothyronine (T3) and thyroxine (T4). While T4 is the most abundant thyroid hormone, it is not particularly active. 30% of T4 is converted into the more active T3, which controls the usage of energy (metabolic rate) of almost all organs and tissues in the body [R, R, R].

Most (>99.5%) T4 in the blood is bound to and transported by different proteins. Only a small fraction (~0.5%) of T4 is free. This test measures both T4 forms together [R].

Total T4 is often measured to check if the thyroid is working well and to help diagnose hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid). TSH and free T4 levels may also be needed for your doctor to make an accurate diagnosis [R].

This test measures the amount of free thyroid hormone T4 (thyroxine) in the blood.

Thyroxine (T4) is a hormone made in the thyroid gland from iodine and the amino acid tyrosine. It serves as a precursor to the more active thyroid hormone called triiodothyronine, or T3. T3 controls the usage of energy (metabolic rate) and thereby affects almost all organs and tissues in the body, including the brain, heart, bones, muscles, liver, pancreas, and fat tissue. Thyroid hormones adjust cholesterol levels, energy production, and insulin sensitivity [R].

Most (>99%) of the T4 in the blood is bound to and transported by different proteins. Only a small fraction (~0.03%) of T4 is free. T4 is active and can be converted into T3 only in its free form [R].

Free T4 is often measured together with thyroid-stimulating hormone (TSH) to check if the thyroid is working well and to help diagnose hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid) [R].

This test measures your total iron-binding capacity (TIBC).

TIBC is the total capacity of your blood to bind and transport iron [R, R].

TIBC is an indirect measure of transferrin, a protein that binds iron molecules and transports them into the bloodstream. Transferrin is produced in the liver and it's the main iron-binding protein in the blood [R, R].

Because they basically measure the same thing, TIBC and transferrin tests may be redundant. TIBC is cheaper, but transferrin is more accurate. A doctor can help you choose the right tests for your circumstances.

This test measures the amount of thyroid-stimulating hormone (TSH) in the blood.

TSH levels are used to check if the thyroid gland is working well.

Thyroid-stimulating hormone is a hormone released by the pituitary gland that signals the thyroid gland to release other hormones. The thyroid gland is the butterfly-shaped gland in the neck that produces thyroxine (T4) and triiodothyronine (T3). T4 and T3 control how fast your metabolism runs [R]. 

TSH is often the first test used to determine whether someone has too little (hypothyroidism) or too much thyroid hormone (hyperthyroidism) [R].

TSH normally increases as we age [R, R].

This test measures the percentage of testosterone that is bioavailable, which means it is easily used by cells and tissues. 

Testosterone is a hormone mainly produced by the testes in men or ovaries in women, with small amounts (<10%) produced by the adrenal glands and brain in both sexes. It is made from cholesterol and it's produced in response to luteinizing hormone (LH), which is released from the pituitary gland [R].

Testosterone has a diverse range of effects on many different organs and tissues. It [R, R, R]:

• improves bone health by increasing bone growth and reducing the breakdown of bone
• helps to build and maintain muscle mass and strength and increases lean body mass
• increases red blood cell production
• improves libido and sexual function
• increases sperm production
• plays a role in mood and brain function

Approximately 2-3% of testosterone is free. 33-54% percent is weakly bound to albumin, and the remaining 44-65% is bound to sex hormone-binding globulin (SHBG) [R].

Testosterone that is free or bound to albumin is considered bioavailable. It is called “bioavailable” because it is easily “available” to be used by cells, which the testosterone bound to SHBG is not because it is strongly attached.

Bioavailable testosterone, like free and total testosterone, declines with age in both men and women after peaking in the late 20s. However, because SHBG increases with age and binds more testosterone, bioavailable testosterone levels decline even more than total testosterone levels [R, R, R].

Andropause (the male counterpart of menopause) is a collection of symptoms including fatigue, erectile dysfunction, and decreased libido in middle-aged men that is due to the age-related decline in testosterone [R, R, R]. 

Because the test for bioavailable testosterone is expensive and difficult to perform, doctors and laboratories often rely on free testosterone instead [R].

You should measure your bioavailable testosterone levels in the early morning when they are at their peak [R].

This test measures the amount of bioavailable testosterone, which is easily used by cells and tissues. 

Testosterone is a hormone mainly produced by the testes in men or ovaries in women, with small amounts (<10%) produced by the adrenal glands and brain in both sexes. It is made from cholesterol and it's produced in response to luteinizing hormone (LH), which is released from the pituitary gland [R].

Testosterone has a diverse range of effects on many different organs and tissues. It [R, R, R]:

• improves bone health by increasing bone growth and reducing the breakdown of bone
• helps to build and maintain muscle mass and strength and increases lean body mass
• increases red blood cell production
• improves libido and sexual function
• increases sperm production
• plays a role in mood and brain function

Approximately 2-3% of testosterone is free. 33-54% percent is weakly bound to albumin, and the remaining 44-65% is bound to sex hormone-binding globulin (SHBG) [R].

Testosterone that is free or bound to albumin is considered bioavailable. It is called “bioavailable” because it is easily “available” to be used by cells, while the testosterone bound to SHBG is not because it is strongly attached.

Bioavailable testosterone, like free and total testosterone, declines with age in both men and women after peaking in the late 20s. However, because SHBG increases with age and binds more testosterone, bioavailable testosterone levels decline even more than total testosterone levels [R, R, R].

Andropause (the male counterpart of menopause) is a collection of symptoms including fatigue, erectile dysfunction, and decreased libido in middle-aged men that is due to the age-related decline in testosterone [R, R, R]. 

Because the test for bioavailable testosterone is expensive and difficult to perform, doctors and laboratories often rely on free testosterone instead [R].

You should measure your bioavailable testosterone levels in the early morning when they are at their peak [R].

This test measures the amount of free testosterone in your blood.

Free testosterone is testosterone that is not bound to any proteins. 

Testosterone is a hormone mainly produced by the testes in men or ovaries in women, with small amounts (<10%) produced by the adrenal glands and brain in both sexes. It is made from cholesterol and it's produced in response to luteinizing hormone (LH), which is released from the pituitary gland [R].

Testosterone has a diverse range of effects on many different organs and tissues. It [R, R, R]:

• improves bone health by increasing bone growth and reducing the breakdown of bone
• helps to build and maintain muscle mass and strength and increases lean body mass
• increases red blood cell production
• improves libido and sexual function
• increases sperm production
• plays a role in mood and brain function

Approximately 2-3% of testosterone is free. 33-54% percent is weakly bound to albumin, and the remaining 44-65% is bound to sex hormone-binding globulin (SHBG) [R].

Free testosterone declines with age in both men and women after peaking in the late 20s [R, R]. 

Low testosterone levels are associated with a risk of heart disease. Andropause (the male counterpart of menopause) is a collection of symptoms including fatigue and decreased libido in middle-aged men that is due to the age-related decline in testosterone [R]. 

Free testosterone levels are less often ordered than total testosterone because it is more expensive and more difficult to measure them. However, it may be necessary to test free testosterone levels in men and women who have symptoms of low testosterone but have normal total testosterone levels [R].

This test measures the amount of free testosterone in your blood [R].

Free testosterone is testosterone that is not bound to any proteins. 

Testosterone is a hormone mainly produced by the testes in men or ovaries in women, with small amounts (<10%) produced by the adrenal glands and brain in both sexes. It is made from cholesterol and it's produced in response to luteinizing hormone (LH), which is released from the pituitary gland [R].

Testosterone has a diverse range of effects on many different organs and tissues. It [R, R, R]:

• improves bone health by increasing bone growth and reducing the breakdown of bone
• helps to build and maintain muscle mass and strength and increases lean body mass
• increases red blood cell production
• improves libido and sexual function
• increases sperm production
• plays a role in mood and brain function

Approximately 2-3% of testosterone is free. 33-54% percent is weakly bound to albumin, and the remaining 44-65% is bound to sex hormone-binding globulin (SHBG) [R].

Free testosterone declines with age in both men and women after peaking in the late 20s [R, R]. 

Low testosterone levels are associated with a risk of heart disease. Andropause (the male counterpart of menopause) is a collection of symptoms including fatigue and decreased libido in middle-aged men that is due to the age-related decline in testosterone [R]. 

Free testosterone levels are less often ordered than total testosterone because it is more expensive and more difficult to measure them. However, it may be necessary to test free testosterone levels in men and women who have symptoms of low testosterone but have normal total testosterone levels [R].

This test measures the amount of total testosterone in your blood. 

Total testosterone includes testosterone bound to proteins (sex hormone-binding globulin (SHBG) and albumin) and free testosterone, not bound to any proteins.

Testosterone is a hormone mainly produced by the testes in men or ovaries in women, with small amounts (<10%) produced by the adrenal glands and brain in both sexes. It is made from cholesterol and it's produced in response to luteinizing hormone (LH), which is released from the pituitary gland [R].

Testosterone has a diverse range of effects on many different organs and tissues. It [R, R, R]:

• improves bone health by increasing bone growth and reducing the breakdown of bone
• helps to build and maintain muscle mass and strength and increases lean body mass
• increases red blood cell production
• improves libido and sexual function
• increases sperm production
• plays a role in mood and brain function

Approximately 2-3% of testosterone is free. 33-54% percent is weakly bound to albumin, and the remaining 44-65% is bound to sex hormone-binding globulin (SHBG) [R].

Starting around the age of 30, total testosterone levels begin to decline by 0.4-2% every year [R].

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of thyroglobulin antibodies in the blood. 

Thyroglobulin antibodies are an antibody that attacks your thyroid gland. Thyroglobulin antibodies target a protein called thyroglobulin [R]. 

Thyroglobulin (Tg) is made in the thyroid gland and is the building block of the thyroid hormones T4 and T3.

Antibodies to thyroglobulin (TgAb) are commonly found in people with autoimmune hypothyroidism and hyperthyroidism. More than 50% of people with these diseases test positive for TgAb. TgAbs are also sometimes detected in people with normal thyroid function [R].

Your doctor may order this test to determine whether your hypothyroidism or hyperthyroidism is autoimmune in nature. 

Thyroglobulin antibodies can also be measured in addition to thyroglobulin, because they can interfere with thyroglobulin levels [R].

This test measures the amount of thyroid peroxidase antibodies in the blood.

Thyroid peroxidase (TPO) is an enzyme found mainly in the thyroid gland, where it prepares iodine to be attached to thyroglobulin (Tg), the protein that serves as the building block of thyroid hormones (T4 and T3).

Antibodies to TPO (TPOAb), also known as anti-microsomal antibodies, are commonly found in patients with autoimmune hypothyroidism (Hashimoto’s thyroiditis, atrophic thyroiditis, and postpartum thyroiditis) and hyperthyroidism (Graves’ disease and postpartum thyroiditis), with more than 80% of patients with these diseases testing positive. They are also sometimes detected in people with normal thyroid function [R].

TPO antibodies tag the enzyme as a harmful substance and cause the body to mount an immune response, damaging the thyroid in the process and causing thyroid dysfunction [R].

TPO antibodies are one of many antibodies directed against components of the thyroid, such as thyroglobulin, thyroid-stimulating hormone receptor (TSHR), and rarely, thyroid hormones themselves. Of these, TPO antibodies are the most common and most indicative of thyroid disease [R].

Women are about twice as likely as men to test positive for TPO antibodies [R, R].

Your doctor may order a TPO antibody test to check if your hypothyroidism (low thyroid hormones) or hyperthyroidism (high thyroid hormones) is autoimmune in nature.

*Your lab range may differ from our normal range. In the case of TPO antibodies, the closer you are to zero the better.

Remember that there is some lab-to-lab variability in ranges due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal. 

This test measures the number of HDL particles in your blood.

A standard lipid panel will measure the amount of cholesterol. Reducing bad and increasing good cholesterol has been the primary target for doctors in treating and preventing heart disease. However, scientists found that almost 50% of people who have a heart attack have normal blood cholesterol levels [R, R, R]. 

This has led researchers to look beyond cholesterol -- into cholesterol-carrying particles, which may better predict the risk of heart disease [R, R, R].

To help visualize the difference between HDL cholesterol and HDL particles, you can think of HDL particles as cars on a highway (blood vessel) and cholesterol molecules as the passengers. HDL cholesterol is a measure of the number of passengers on the roads, while the number and size of HDL particles represents the number and the size of the cars [R].  

Cholesterol transported by HDL is known as “good cholesterol” because it is being removed from cells and artery walls, which helps prevent, reduce, and even reverse hardening of the arteries (atherosclerosis) and accumulation of fatty plaques [R, R]. 

HDL particles differ in size and function. They can be large (i.e. HDL2) or small (HDL3). At present, most commercial assays will provide the total number of HDL particles or the number of large HDL particles (HDL2).

The ratio of your blood triglycerides and your "good cholesterol" HDL-C levels can be used to help predict heart disease risk [R]. 

In general, the smaller the number the better, as this means that your HDL-C (the “good cholesterol”) is high compared to triglycerides.

This test measures the amount of triglycerides circulating in your blood.

Triglycerides (TG) are the most common type of fat in your body. 

You get triglycerides from food, such as meat, dairy, vegetable oils, and fats. Triglycerides are digested and absorbed in the small intestine and then packaged together with cholesterol and proteins. These packages can then be used by cells as a form of energy [R, R]. 

The liver is also able to make and store triglycerides. It does so when you eat a lot of carbs, or more calories than your body needs [R, R, R].

It's important to watch your triglyceride levels and maintain them in a healthy range. High triglyceride levels are associated with an increased risk of developing heart disease [R, R].

This test measures the amount of transferrin in the blood that has not been bound with iron.

Unsaturated iron-binding capacity (UIBC) measures the “reserve capacity” of transferrin, or the amount of transferrin that has not yet been saturated with iron.

Together with total iron-binding capacity (TIBC), transferrin, and transferrin saturation tests, UIBC tests are used to evaluate the blood’s ability to bind and transport iron.

This test measures uric acid in your blood.

Uric acid is made in the liver. It is the end product of the breakdown of purines, which are produced in the digestion of certain proteins and DNA. Purines are released into the bloodstream when cells age and die. Some purines are also derived from foods [R, R].

In normal conditions, most of the uric acid is removed by the kidneys through urine, while the rest is removed with feces [R].

However, if too much uric acid is produced or not enough is removed, it can build up in the blood. Then, uric acid crystals can deposit in the body, causing kidney stones or gout [R, R].

On the other hand, scientists have discovered that uric acid is not solely a waste product. In fact, studies suggest that uric acid acts as a natural antioxidant and may account for up to 60% of the antioxidant capacity of the blood. In addition, uric acid can protect the brain by preventing neurodegenerative diseases [R, R, R, R].

Therefore, balanced uric acid levels are important for general well-being.

Blood uric acid increases with age. Men tend to have higher levels than women, and are therefore at greater risk of developing gout. This may be because estrogen helps eliminate uric acid through the kidneys [R, R].

Remember there is certain variability in the ranges from lab to lab due to differences in the equipment, techniques, and chemical reagents used. Don't panic if your result is slightly out of range on the app; As long as it's within the normal range according to the lab that performed the test, its value is normal.

This test measures the levels of urobilinogen in your urine.

Urobilinogen is a colorless pigment made from bilirubin by gut bacteria. The majority of urobilinogen is excreted in feces, and a small amount is reabsorbed and excreted in the urine [R]. 

Urobilinogen levels in the urine can rise when bilirubin production increases because of red blood cell destruction (hemolysis) or liver disease. Because of this, a urobilinogen test is used with other tests to help detect liver, gallbladder, or red blood cell problems [R, R]. 

A urobilinogen test is usually done as a part of a routine urinalysis test, which measures several other substances in your urine, including proteins, ketones, and glucose [R].

This test calculates the amount of very-low-density lipoprotein cholesterol, or VLDL-C, in your blood.

VLDL-cholesterol is cholesterol bound to very-low-density lipoprotein (VLDL) particles. It transports triglycerides (fats) and cholesterol in the bloodstream [R].

VLDL-cholesterol is made in the liver and then released into the blood. Once in the blood, it can be converted to LDL-C. VLDL-C, like LDL-C, is considered a form of “bad cholesterol” because it transports and deposits fats and cholesterol in blood vessel walls and contributes to LDL-C levels [R]. 

VLDL-cholesterol is calculated from your fasting triglyceride levels. The result becomes less accurate if it's not taken in a fasted state or if the triglyceride levels are increased (above 400 mg/dL or 4.5 mmol/L). Direct measurement requires specialized testing.

This test looks at the size of VLDL particles in your blood.

A standard lipid panel measures the amount of different types of cholesterol in the blood. For decades, reducing bad cholesterol has been the primary target for doctors in treating and preventing heart disease. However, scientists found that almost 50% of people who have a heart attack have normal cholesterol levels [R, R, R]. 

This has led researchers to look beyond cholesterol, into LDL, HDL, and VLDL particles, which may better predict the risk of heart disease [R, R, R].

To help visualize the difference between VLDL-cholesterol (VLDL-C) and VLDL particles, you can think of VLDL particles as cars on a highway (blood vessel) and cholesterol molecules as the passengers. VLDL-C is a measure of the number of passengers on the roads, while the number and size of VLDL particles represents the number and the size of the cars [R].  

Scientists found that it's better to have smaller VLDL particles [R, R, R].

This test measures vitamin B12 levels in your blood.

(Methyl)cobalamin, more commonly known as vitamin B12, is a vital dietary nutrient [R]. It's needed for:

• Making blood cells (hematopoiesis) [R, R]
• Creating, replicating, and repairing DNA [R, R, R]
• Healthy brain and nervous system function [R, R, R]

Our bodies can't make vitamin B12 and therefore it must come from dietary sources, mainly animal products such as meat and dairy [R, R].

The body uses vitamin B12 very efficiently, essentially recycling it as it is used. In fact, a healthy person can store up to 3-6 years’ worth of vitamin B12 in their liver! For this reason, vitamin B12 deficiencies are quite rare and indicate a very long-term shortage of this nutrient in the diet [R].

Some populations at higher risk of B12 shortage include:

• Vegans and vegetarians [R, R, R]
• Pregnant and breastfeeding women [R, R]
• The obese [R, R]
• People who have gastrointestinal disorders that make absorbing B12 from the diet difficult or less efficient [R, R, R]
• Heavy alcohol drinkers [R, R]
• AIDS/HIV patients [R, R]
• Elderly people, as the gut becomes less efficient at absorbing nutrients with age [R, R, R]

This test measures the amount of (25-hydroxy) vitamin D in your blood. 

Known as the “sunshine vitamin,” vitamin D helps maintain healthy levels of calcium and phosphorus by increasing their absorption in the gut. In this way, vitamin D is critical for bone health [R, R]. Vitamin D also plays a role in muscle strength and performance, immune function, cell production, blood pressure, and insulin secretion [R, R, R, R].

Vitamin D is produced by the skin upon exposure to sunlight. It can also be obtained in the diet, or through vitamin supplements [R].

Your skin first produces vitamin D3 (cholecalciferol), which is then activated in the liver and kidneys. More specifically, liver converts vitamin D into 25-hydroxyvitamin D (25[OH]D), the major circulating form of vitamin D. This form is then converted in the kidneys to the active 1,25-dihydroxyvitamin D form [R, R]. 

Vitamin D can be stored in fat tissue and is found throughout the body including bones, kidneys, heart, stomach, liver, skin, brain, ovaries, and testes [R, R].

Although 1,25-dihydroxy is the active form of vitamin D, its levels can be normal or even high in people who are otherwise deficient in overall vitamin D. For this reason, active vitamin D is not a good measurement of your vitamin D status [R]. Instead, 25-hydroxyvitamin D is more often used to determine if your vitamin D levels are healthy or abnormal [R].

Doctors will usually perform a vitamin D blood test to diagnose bone problems, detect potential parathyroid gland dysfunction, or monitor the condition of people with diseases that interfere with fat absorption in the intestines (such as Crohn’s disease) [R, R]. 

Vitamin D tests are also used to screen people who are at high risk of deficiency, such as [R, R]:

• People who don't get enough sun
• Older people
• Obese people
• People with darker skin
• Vegans
• Pregnant women and breastfed children

This test measures the amount of vitamin D3 in your blood.

Known as the “sunshine vitamin” because we get a lot of it from sunlight, vitamin D is important for various processes in our bodies. It's vital for bone health, muscle strength, immune function, blood pressure, and insulin release [R, R, R, R, R].

Vitamin D comes in two forms: 

• Vitamin D2 (ergocalciferol) is found in fungi and some plants. The best food sources are sun-dried and UV-light-exposed mushrooms. It's also available as a supplement [R, R].
• Vitamin D3 (cholecalciferol) is produced by the skin upon exposure to sunlight. It can also be obtained by eating fatty fish (e.g. salmon, tuna) and egg yolks, or through supplements [R, R, R, R].

Both vitamin D2 and D3 get converted in the liver into the major circulating form of vitamin D (25-hydroxyvitamin D), which is further converted in the kidneys to the active form (1,25-dihydroxyvitamin D) as needed [R, R].

Studies have been controversial when it comes to vitamin D2 vs. vitamin D3 supplementation. Some found no difference between the two while others found D3 to be superior [R, R, R, R, R, R, R, R, R, R, R, R].

This disparity appears to be due to differences in dosing. Namely, D3 seems to be more potent than D2 when given on occasion at higher doses, but both forms appear equally beneficial when given daily at lower doses. This is likely because D2 has a shorter life cycle in the body [R, R].

However, because of their higher potency, vitamin D3 supplements are easier to overdose with [R].

There is no defined normal range for vitamin D3. This test reflects the amount of vitamin D3 you get from the sun + diet + supplements. To check if you have enough vitamin D, you need a standard total vitamin D (25-hydroxyvitamin D) test [R].

This test measures the total number of white blood cells (WBCs) in your blood.

White blood cells, also known as leukocytes, fight invaders such as bacteria and viruses, shielding us against infections and diseases. When we experience an infection or there is inflammation somewhere in the body, the bone marrow will make more white blood cells to deal with it [R].

Therefore, a high WBC count can alert your doctor to an ongoing infection or inflammation [R].

A low WBC count, on the other hand, can signal problems such as autoimmune conditions, immune deficiencies, and bone marrow disorders [R, R].

If your white blood cells are increased or decreased, it is important to check the count of each different type of white blood cell to find what cells are responsible for your low or high WBC count. There are 5 major types of WBCs: lymphocytes, neutrophils, monocytes, eosinophils, and basophils [R].

A WBC count can detect that there is a health issue, but cannot determine the underlying cause. Your doctor will interpret this test in conjunction with your medical history and signs and symptoms, to decide if further tests are necessary. 

Remember that some lab-to-lab variability occurs due to differences in equipment, techniques, and chemicals used. Don't panic if your result is slightly out of range in the app - as long as it's in the normal range based on the laboratory that did the testing, your value is normal.

This test measures the amount of zinc in the blood in order to identify/diagnose deficiency or to monitor response to supplementation.

Zinc is an essential mineral found in all organs, tissues, and fluids in the body. It is required for the activity of more than 300 enzymes. It's involved in the production and metabolism of carbs, fats, proteins, and nucleic acids [R, R, R].

Zinc also plays roles in [R]:

• Stabilizing cell and organ structures
• Immune function
• Wound healing
• Cell division and growth
• Blood clotting
• Stomach acid production
• Thyroid function
• Vision, taste, and smell 

Despite having such critical functions, zinc is not stored in the body, and therefore requires a regular dietary intake [R].

Groups at risk for zinc deficiency include [R, R, R]:

• People with digestive disorders
• Malnourished individuals
• Vegetarians
• Pregnant and lactating women
• Alcoholics
• The elderly
• People with sickle cell disease

Estimated average glucose (eAG) is calculated from your HbA1c levels, which are a measure of your 3-month average blood sugar levels [R]. 

eAG and HbA1c are basically the same. However, eAG was designed to be more easily understood by laypeople, and it's useful because it's in the same range and units diabetics see on their glucose monitors [R].

If you're a diabetic, a valid question you may have is why the eAG doesn't match the average glucose level shown on your personal monitor. It's because the average glucose on your monitor is biased. For example, you are more likely to check your glucose when your blood sugar is low: first thing in the morning and before meals. If that's the case your average glucose will be lower than eAG.

eAG is more accurate than the average blood glucose on your monitor because it accounts for the glucose levels 24h a day, including peaks after meals. It is a better measure of how you are managing your blood sugar overall.

Estimated glomerular filtration rate (eGFR) is a measure of how well your kidneys are working.

GFR is the amount of blood that is filtered every minute by tiny filters in the kidneys called glomeruli [R].

When kidney function declines due to damage or disease, GFR decreases and waste products that are normally released in the urine start to appear in the blood.

Your eGFR is calculated based on your blood creatinine levels, sex, age, and race. Creatinine is a waste product that is normally filtered by the kidneys and released into the urine at a relatively steady rate. When kidney function decreases, less creatinine is removed through urine and levels in the blood increase.

Early detection of impaired kidney function is important to prevent further kidney damage. Ask your doctor to explain your results.

Because creatinine depends on muscle mass, conditions such as wasting disease and obesity require alternative ways to obtain eGFR. In addition, for body builders, high muscle mass may lead to underestimation of eGFR [R].

This test is a highly sensitive test that measures the amount of C-reactive protein (CRP) in your blood.

CRP is a protein made in the liver in response to [R, R]:

• injury
• infection
• inflammation

CRP binds to damaged tissue or microbes and tags them so the immune system can clear them away [R, R]. 

In addition to being a measure of inflammation in the body, higher CRP levels have also been associated with the hardening of the arteries and a higher risk of heart disease [R, R, R]. 

To get an estimate of chronic low-grade inflammation in the body, you need the highly-sensitive CRP (hs-CRP) test. A regular CRP test only detects very high elevations that happen in serious infections, inflammatory disorders, or autoimmune conditions [R]. 

Based on hs-CRP, the American Heart Association and CDC have defined the following risk groups:

• Low risk: less than 1.0 mg/L
• Average risk: 1.0 to 3.0 mg/L
• High risk: above 3.0 mg/L

CRP levels are only part of a total risk evaluation for heart disease. Other important risk factors for heart disease include high cholesterol, triglycerides, high blood pressure, diabetes, and smoking.

This test checks the pH of your urine.

Urine pH is a measure of how acidic or alkaline your urine is. Normally, urine is slightly acidic (5.5 to 6.5). It is a bit more alkaline in the morning compared to the night and women tend to have higher urine pH levels than men [R, R, R].

Kidneys control the pH of blood and urine by filtering acids from the blood and excreting them in the urine [R]. 

Diet, certain drugs, infections, and poor kidney function can all affect your urine pH. Diets high in protein from meat, fish, dairy, and grains can decrease urine pH (making it more acidic), whereas diets high in fruits and vegetables can increase urine pH (making it more alkaline) [R, R, R].

Having urine pH that is too high or too low may increase the risk of kidney stones [R].