Your guide to blood biomarkers

Fasting glucose is the amount of sugar in your blood when you haven't eaten for at least eight hours and an important snapshot of your metabolic health.

Fasting insulin is your insulin level independent of a recent meal and measures how well you are producing this crucial hormone, which helps keep blood sugar stable.

The HbA1c test assesses your average blood sugar over the past two to three months by detecting glycated hemoglobin, which forms when glucose bonds to hemoglobin in red blood cells.

Leptin is a hormone produced primarily by fat cells that signals to your brain about your body's energy stores and helps regulate appetite, metabolism, and body weight.

Uric acid is a natural compound produced by your body when it breaks down purines, found in certain foods and also created as part of normal cellular processes.

Free T4 measures the unbound, biologically active form of thyroxine in your blood, providing a direct assessment of thyroid hormone availability to your body's tissues.

T3 uptake is an indirect measure of thyroid hormone-binding protein capacity in your blood, helping to interpret whether abnormal total T4 levels reflect true thyroid dysfunction or changes in binding proteins.

Thyroglobulin antibodies (TgAb or Tg antibodies) are autoantibodies that target thyroglobulin, a protein essential for thyroid hormone production, and their presence may indicate autoimmune thyroid disease or complicate the monitoring of thyroid cancer.

Thyroid peroxidase antibodies (TPO antibodies or TPOAb) are autoantibodies that target thyroid peroxidase, an enzyme essential for thyroid hormone production, and their presence may indicate autoimmune thyroid disease.

Thyroid-stimulating hormone (TSH) is a "master" thyroid hormone that regulates the production of thyroid hormones.

Total T3 measures all triiodothyronine in your blood, including both bound and free forms of this potent thyroid hormone.

Total T4 measures all thyroxine in your blood, including both the bound and free forms of this major thyroid hormone.

Hematocrit is the percentage of your total blood volume that is made up of red blood cells. The remaining portion consists primarily of plasma, the liquid component of blood.

Hemoglobin is the iron-containing protein in red blood cells that carries oxygen from your lungs to all your body's tissues.

Mean corpuscular hemoglobin (MCH) is a measurement of the average amount of hemoglobin contained in each of your red blood cells.

Mean corpuscular hemoglobin concentration (MCHC) is a measurement of the average concentration of hemoglobin inside your red blood cells.

Mean corpuscular volume (MCV) measures the average size of your red blood cells.

Mean platelet volume (MPV) measures the average size of your platelets, the small blood cells responsible for blood clotting.

Platelets (thrombocytes) are small, disc-shaped cell fragments that circulate in blood and aid blood clotting, helping your body stop bleeding after injury.

Red blood cell (RBC) count, also called erythrocyte count, measures the total number of red blood cells in your blood.

Red cell distribution width (RDW) measures the variation in the size of your red blood cells.

Arachidonic acid (AA) is an omega-6 fatty acid found in animal products and can be derived from linoleic acid in plants. It plays key roles in inflammation, cell signaling, and brain health.

The ratio of arachidonic acid (AA) to eicosapentaenoic acid (EPA) measures the pro-inflammatory (AA) and anti-inflammatory (EPA) fatty acids in your body to indicate your overall inflammatory status.

Docosahexaenoic acid (DHA) is one of the body's three primary omega-3 fatty acids. It is used for cell membranes that support the brain, eyes, and nervous system. DHA also helps control inflammation and supports immune function.

Docosapentaenoic acid (DPA) is an omega-3 fatty acid that acts as both an active anti-inflammatory compound and a reservoir for other omega-3s.

Eicosapentaenoic acid (EPA) is an omega-3 fatty acid found mainly in fatty fish and fish and algae oil supplements. Your body uses EPA to make molecules that affect blood flow, immune function, and how your cells communicate with each other.

Ferritin, a protein that stores and regulates iron release, is one indicator of your body's iron stores and also acts as an important marker of inflammation.

Homocysteine is an amino acid that your body uses to create proteins and other amino acids.

Iron is an essential mineral that carries oxygen throughout your body and supports energy production. Testing iron levels helps identify deficiencies or excess that can impact oxygen transport, energy levels, immune function, and overall health before symptoms become severe.

Total iron binding capacity (TIBC) evaluates how much iron your blood can carry by measuring transferrin, the protein responsible for transporting iron throughout your body.

Iron saturation measures the percentage of iron-carrying protein (transferrin) currently carrying iron. This can detect iron imbalances earlier than storage tests like ferritin, making it a valuable tool for comprehensive iron assessment.

Linoleic acid is the primary omega-6 fatty acid in your diet and serves as a precursor for other omega-6 fatty acids, including arachidonic acid.

Magnesium is a crucial mineral involved in more than 300 biochemical reactions. It is particularly important for energy production and muscle, nerve, and heart function.

The omega-6 to omega-3 ratio indicates the balance between competing essential fatty acids in your body.

Total omega-3 measures all forms of omega-3 fatty acids in your blood, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), and alpha-linolenic acid (ALA).

Omega-6 fatty acids are essential nutrients that support immune function, brain development, and skin health. Testing total omega-6 levels helps evaluate whether you have a healthy balance with omega-3 fatty acids, which influences the inflammatory response and overall metabolic health.

OmegaCheck measures levels of three omega-3 polyunsaturated fatty acids (called PUFAs) in your blood; higher levels may reduce the risk of heart disease and have other health benefits.

Methylmalonic acid (MMA) accumulates in the body when there is insufficient vitamin B12 to process certain molecules properly. Testing MMA levels provides a sensitive indicator of functional vitamin B12 status in the body.

Vitamin D is involved in many of your body's most important functions and affects nearly every cell in your body. The 25-hydroxy version is the predominant form, circulating in your blood for weeks to months.

Zinc is an essential trace mineral involved in hundreds of biochemical processes throughout the body. Unlike some nutrients, the body has no specialized zinc storage system, making regular dietary intake necessary.

Calcium is an essential mineral that's particularly important for bone formation, growth, and strength. It also plays a vital role in cellular communication, so calcium levels in the blood can help assess the health of several of your body's systems, and evaluate kidney and thyroid health.

Sodium is an important electrolyte and essential mineral that helps regulate several things in your body, including blood pressure, fluid balance, and nerve signaling. A sodium blood test can reveal how well your body maintains fluid and electrolyte balance through the coordinated action of your kidneys, adrenal glands, and various hormones.

Alanine aminotransferase (ALT) is an enzyme primarily found in liver cells (hepatocytes). When liver cells are damaged or die, they release ALT into the bloodstream, so ALT is one of the most reliable signs of liver health and injury.

Albumin is a liver-produced protein that transports nutrients and medications while maintaining fluid balance, serving as an indicator of both liver function and medium-term health.

The Albumin/Globulin ratio compares two key blood proteins that typically move in opposite directions during illness, making it an early indicator of liver problems and inflammation.

Alkaline phosphatase (ALP) is an enzyme found throughout the body. The highest concentrations are in the liver, bile duct, bones, kidneys, intestines, and, when pregnant, the placenta. When analyzed alongside other blood markers, ALP levels can be used as an indicator of health across different systems.

Aspartate aminotransferase (AST) is an enzyme in the liver, muscles, and other tissues. Elevated levels indicate potential tissue damage, often requiring additional tests to determine whether the cause is liver disease, muscle injury, or another underlying condition.

Gamma-glutamyl transferase (GGT) is an enzyme primarily found in the liver, but also present in the kidneys, bile ducts, pancreas, heart, and other organs.

Globulins are a group of proteins in your blood that play roles in immunity, inflammation, and the transport of various substances throughout your body.

Bilirubin is a natural product of old red blood cell breakdown (hemolysis); it can reflect both liver function and hemolysis (excessive red blood cell destruction) and can serve as an antioxidant.

Proteins are complex molecules made of amino acid chains that serve as building blocks throughout the body. Blood proteins, measured in this test, are specialized proteins that support the transportation of substances through the body and serve as indicators of kidney and liver health.

Blood Urea Nitrogen (BUN) measures the amount of urea nitrogen (a waste product of protein metabolism) in the blood, produced when the liver breaks down proteins and filtered by the kidneys for excretion in urine.

The blood nitrogen urea (BUN)/creatinine ratio compares two kidney-filtered waste products to help determine whether changes in kidney function are due to problems with the kidneys themselves or other bodily issues.

Bicarbonate (HCO3) level in a regular blood draw measures carbon dioxide (CO₂), which is primarily in the form of bicarbonate, a key buffer that maintains your blood's pH balance by neutralizing excess acidic ions.

Chloride is your blood's primary negatively charged electrolyte. It is essential for maintaining proper fluid balance and acid-base status throughout your body.

Creatinine, a waste product created from muscle energy production, is an indicator of kidney function, though its levels need to be evaluated in the context of many other factors such as muscle mass.

Creatinine with GFR Estimated (eGFR) is a blood test that checks how well your kidneys are functioning by measuring your creatinine level and estimating filtration ability based on your age, sex, and other personal characteristics.

Cystatin C is a protein that provides a more accurate measure of kidney function than traditional tests because it's produced consistently by all cells and filtered almost entirely by the kidneys, making it independent of factors like muscle mass that can affect other kidney markers.

Estimated Glomerular Filtration Rate (eGFR) is a calculated value that estimates how well your kidneys filter blood. It uses an equation that takes into account cystatin C values along with other factors such as age and sex.

Potassium is a mineral and electrolyte involved in nerve function, muscle contraction, and heart rhythm.

Basophils are the least common type of white blood cell (leukocyte), typically making up less than 1 percent of your total white blood cell count.

Basophils are the least common type of white blood cell (leukocyte), typically making up less than 1 percent of your total white blood cell count.

Eosinophils are a type of white blood cell (leukocyte) that play important roles in allergic responses, fighting parasitic infections, and regulating inflammation.

Eosinophils are a type of white blood cell (leukocyte) that play important roles in allergic responses, fighting parasitic infections, and regulating inflammation.

Lymphocytes are a type of white blood cell (leukocyte) and are key players in your immune system's ability to fight infections and diseases.

Lymphocytes are a type of white blood cell (leukocyte) and are key players in your immune system's ability to fight infections and diseases.

Monocytes are the largest type of white blood cell (leukocyte) in your bloodstream and are versatile frontline defenders in your immune system. They patrol the bloodstream, ready to respond to infection or tissue damage, and transform into macrophages that engulf cellular debris, microbes, and cancer cells. Measuring monocyte levels helps evaluate inflammatory and infectious processes, detect blood disorders, and assess immune system function.

Monocytes are the largest type of white blood cell (leukocyte) in your bloodstream and are versatile frontline defenders in your immune system.

Neutrophils are the most abundant type of white blood cell (leukocyte) in your bloodstream, typically making up 50--70 percent of your total white blood cells.

Neutrophils are the most abundant type of white blood cell (leukocyte) in your bloodstream, typically making up 50--70 percent of your total white blood cells.

White blood cell (WBC) count, also called a leukocyte count, measures the total number of white blood cells in your blood and is a broad measure of immune status.

Bioavailable testosterone measures the portion of testosterone that is readily available for your body to use, including both free testosterone and testosterone loosely bound to albumin. This test provides a more complete picture of usable testosterone than free testosterone alone.

Follicle-stimulating hormone (FSH) plays a role in sexual development and reproductive health in both females and males. Testing FSH levels helps evaluate fertility issues, determine ovarian and testicular function, and diagnose hormonal disorders affecting reproductive health.

Free testosterone is the small but biologically active portion of total testosterone that is not bound to carrier proteins in the blood. Testing it can provide a more accurate picture of hormonal status than total testosterone alone.

Luteinizing hormone (LH) is a reproductive hormone produced by the pituitary gland in both men and women. LH helps regulate ovulation and progesterone production in women and testosterone production in men.

Prolactin is a hormone primarily produced by the pituitary gland, a small pea-sized gland at the base of the brain. While best known for stimulating milk production in pregnant and nursing women, prolactin affects many bodily functions in both women and men.

Prostate-specific antigen (PSA) is a protein produced by the prostate gland in men. The % free PSA test measures the ratio of PSA in the blood that isn't bound to protein ("free" PSA) to total PSA and can suggest whether follow-up testing is useful to diagnose a condition.

Prostate-specific antigen (PSA) is a protein produced by the prostate gland in men. Free PSA is the portion of PSA in the blood that isn't bound to proteins. Testing free PSA alongside total PSA can help differentiate between benign conditions and prostate cancer, particularly when total PSA falls in the diagnostic gray zone.

Prostate-specific antigen (PSA) is a protein produced almost exclusively by the prostate gland. PSA is primarily released into seminal fluid, where it helps liquefy semen after ejaculation, but small amounts also enter the bloodstream.

Sex hormone binding globulin (SHBG) is a protein that regulates the availability of sex hormones in your body, particularly testosterone and estrogen. Your SHBG levels can help reveal underlying hormonal imbalances that might affect energy levels, reproductive health, and metabolism in both men and women.

Total testosterone is a measurement of the overall amount of testosterone in your blood, including both free testosterone (not bound to proteins) and testosterone that is bound to carrier proteins (primarily sex hormone-binding globulin and albumin).

Anti-Müllerian Hormone (AMH) is a biomarker for a woman's ovarian reserve, which is the number of follicles (immature eggs) left in the ovaries.

Estradiol is the most potent and abundant form of estrogen, a group of hormones that play roles in reproductive and sexual development, particularly in women. But estradiol is also an important hormone for men.

Follicle-stimulating hormone (FSH) plays a role in sexual development and reproductive health in both females and males. Testing FSH levels helps evaluate fertility issues, determine ovarian and testicular function, and diagnose hormonal disorders affecting reproductive health.

Luteinizing hormone (LH) is a reproductive hormone produced by the pituitary gland in both men and women. LH helps regulate ovulation and progesterone production in women and testosterone production in men.

Prolactin is a hormone primarily produced by the pituitary gland, a small pea-sized gland at the base of the brain. While best known for stimulating milk production in pregnant and nursing women, prolactin affects many bodily functions in both women and men.

Sex hormone binding globulin (SHBG) is a protein that regulates the availability of sex hormones in your body, particularly testosterone and estrogen. Your SHBG levels can help reveal underlying hormonal imbalances that might affect energy levels, reproductive health, and metabolism in both men and women.

Your biological age measures how old your body appears physiologically based on nine blood biomarkers—including glucose, creatinine, albumin, and inflammatory markers—compared to your chronological age. A lower biological age suggests slower aging and reduced disease risk, while a higher biological age may indicate accelerated aging processes.

Cortisol is a steroid hormone produced by the adrenal glands. It plays a role in the body's stress response and also affects metabolism, immune function, and inflammation.

DHEA-S is the sulfated, active form of DHEA, a hormone produced mainly by your adrenal glands that helps your body make testosterone and estrogen. Testing your DHEA-S levels helps identify hormonal imbalances that affect your energy, mood, and reproductive health.

Amylase is an enzyme that helps digest carbohydrates. It's mainly produced in the pancreas and salivary glands.

Lipase is a digestive enzyme mainly produced in the pancreas that helps break down dietary fats into smaller components that can be absorbed by the body.

Amorphous sediment refers to tiny, irregularly shaped particles in urine that can be observed during microscopic examination and can sometimes make the urine appear cloudy. As a laboratory finding, amorphous sediment may indicate various underlying metabolic or dietary conditions affecting kidney function and overall health.

A urinalysis of urine appearance includes color, clarity (clear vs. cloudy), and consistency. While the appearance itself is just a laboratory observation, changes in these characteristics can indicate various conditions, ranging from simple dehydration to more serious health problems.

The test for bacteria in urine is part of a standard urinalysis. It measures whether you have bacterial microorganisms in your urine, technically known as bacteriuria. This marker may indicate you have a urinary tract infection (UTI).

Bilirubin, produced during red blood cell breakdown, should be processed by the liver and eliminated through bile. Its presence in urine can signal liver dysfunction or bile duct issues.

Urine crystals are microscopic structures that form when certain chemicals in urine become highly concentrated and solidify. Although small amounts can be benign, their presence can warrant further testing.

Urinary casts are microscopic cylinder-shaped structures made of proteins or other cellular material that can appear in urine. When observed during laboratory examination, they serve as important diagnostic markers for kidney and urinary tract conditions.

Urine color is a diagnostic marker that can range from clear to dark brown and may include tints like pink, red, blue, or green. The color of urine provides information about hydration status, diet, medications, and potential underlying health conditions.

Urine crystals are microscopic structures that form when certain minerals in urine become highly concentrated and solidify. Their presence, type, and quantity can indicate metabolic conditions, dietary issues, or underlying health problems.

Glucose in urine (glucosuria) usually occurs when there's too much glucose (sugar) in your blood for your kidneys to process. The excess glucose spills into the urine. This can be a sign of high blood sugar levels and diabetes. Testing for glucose in urine is a preliminary screening tool for diabetes.

Granular casts are a specific type of urinary cast, microscopic cylinder-shaped structures found in urine during laboratory examination. Unlike other types of casts (hyaline, cellular, waxy, or fatty), granular casts contain visible granules of degraded cellular material. They are formed in the kidney's tubules and are useful diagnostic markers for specific kidney and urinary tract conditions.

Hyaline casts are colorless, transparent, microscopic cylinder-shaped structures observed in urine during laboratory examination. They consist primarily of protein and are the most common type of urinary cast, often found in small numbers even in healthy people.

Ketones are acidic compounds produced by the liver when it breaks down fat, measured to monitor metabolic status during fasting or diets and to detect potentially dangerous conditions in diabetes.

Leukocyte esterase is an enzyme produced by white blood cells (leukocytes) that can be detected in urine during laboratory testing. Its presence serves as a marker for potential inflammation or infection in the urinary tract and is commonly used as a screening tool for urinary tract infections (UTIs).

Nitrite is a chemical compound that isn't normally present in urine unless you have a urinary tract infection (UTI).

Occult blood in urine means that there is blood in the urine that's not visible to the naked eye but can be detected through laboratory tests.

Urinary pH measures how acidic or alkaline (basic) urine is. This marker reflects the body's acid-base balance and can provide information about kidney and metabolic function, and various health conditions.

Protein is abundant in blood, but if found in urine, it can indicate a problem with kidney health.

Red blood cells (RBCs) in urine occur when blood leaks into the urinary tract. While microscopic amounts are typically not cause for concern, persistent or visible blood in urine is often a sign of an underlying condition.

Renal epithelial cells are specialized cells that line the tiny tubules in the kidney, helping shuttle fluid and substances in and out of the kidneys.

The specific gravity of urine measures its concentration. It's a marker for hydration status and assesses kidney function, including how well the kidney maintains fluid balance and eliminates waste products.

Squamous epithelial cells form the outer layer of skin and line blood vessels and organs. When found in abnormal amounts in urine, they can indicate urinary tract inflammation, infection, or possible contamination during sample collection.

Transitional epithelial cells shed from the lining of your urinary tract that are excreted in urine and can suggest infection or irritation.

Triple phosphate crystals, also known as struvite crystals, are microscopic structures that can be observed in urine during laboratory examination. Their presence is commonly associated with urinary tract infections.

Uric acid crystals are microscopic structures that can be observed in urine during laboratory examination. They form when uric acid (a waste product from purine metabolism) becomes highly concentrated in urine and clumps together. Their presence may indicate metabolic conditions and potential risk for gout or kidney stones.

White blood cells in urine are immune cells that typically occur in your blood, but inflammation or infection in the urinary tract can lead to an elevated appearance in urine.

Yeast in urine (Candiduria) refers to the presence of fungal organisms, typically Candida species, in a urine sample.