Health Library · Biomarkers
Every biomarker, explained in context.
What each marker measures, why clinicians use it, and what can influence your result. Educational information with sources — not a diagnosis.
Liver
- Alanine aminotransferase (ALT)ALT is a liver enzyme that rises when liver cells are stressed or damaged. Learn what an ALT test measures and what can raise it.
- Albumin (blood)Albumin is the main protein made by the liver. What a blood albumin test shows about liver and kidney health and nutrition, and why it is part of routine panels.
- Alkaline phosphatase (ALP)Alkaline phosphatase is an enzyme found mainly in the liver and bones. What an ALP test can indicate and why results are read with other liver and bone markers.
- Aspartate aminotransferase (AST)AST is an enzyme found in the liver, heart and muscles. Learn what an AST test measures and why it's interpreted alongside ALT.
- BilirubinBilirubin is a yellow substance from the normal breakdown of red blood cells. What a bilirubin test shows about the liver and blood, including Gilbert's syndrome.
- Gamma-glutamyl transferase (GGT)GGT is a liver enzyme often used to investigate bile-duct problems and alcohol-related liver stress. Learn what the test shows and what affects it.
Cardiovascular
- Apolipoprotein B (ApoB)ApoB counts the cholesterol-carrying particles that can enter artery walls. Learn what an ApoB blood test measures, why cardiologists use it and how it relates to LDL.
- HDL cholesterolHDL cholesterol helps carry cholesterol away from tissues. Learn what an HDL result means, why higher isn't always better and how it fits into a lipid panel.
- HomocysteineHomocysteine is an amino acid linked to B-vitamin status. What a homocysteine test can show, why levels rise, and what is and isn't known about heart risk.
- LDL cholesterolLDL cholesterol is the main cholesterol measure used to assess cardiovascular risk. Learn what LDL-C is, how it's measured and what affects your result.
- Lipoprotein(a) — Lp(a)Lipoprotein(a) is a largely inherited cholesterol particle linked to cardiovascular risk. Learn what an Lp(a) test measures and why a one-time check is recommended.
- Non-HDL cholesterolNon-HDL cholesterol is total cholesterol minus HDL. Why it captures all cholesterol in artery-clogging particles and how it compares with LDL and ApoB.
- TriglyceridesTriglycerides are the main type of fat in the blood. Learn what a triglyceride test shows, why fasting matters and how results relate to metabolic health.
Kidney
- CreatinineCreatinine is a waste product filtered by the kidneys and the basis of eGFR. Learn what a creatinine test shows and why muscle mass affects it.
- Cystatin CCystatin C is a blood marker used to estimate kidney filtration. How it compares with creatinine, why combining both can help, and what influences it.
- Estimated glomerular filtration rate (eGFR)eGFR estimates how well your kidneys filter blood. Learn what the number means, how it's calculated and when a low result matters.
- Uric acidUric acid is a waste product from breaking down purines. Learn what a uric acid test measures and its link with gout and kidney stones.
Metabolic
- Fasting blood glucoseFasting blood glucose measures sugar in your blood after an overnight fast. Learn how it's used to screen for prediabetes and diabetes and what can affect it.
- Fasting insulinFasting insulin shows how much insulin your body needs to keep glucose stable overnight. Learn how it relates to insulin resistance and its limitations.
- HbA1c (glycated haemoglobin)HbA1c reflects your average blood sugar over roughly 2–3 months. Learn what the test measures, how it's used to screen for diabetes and what affects accuracy.
- HOMA-IR (insulin resistance index)HOMA-IR estimates insulin resistance from fasting glucose and insulin. How it is calculated, where it comes from, and why it is not a diagnostic test on its own.
Nutrition
- FerritinFerritin reflects the body's iron stores. Learn what low and high ferritin can indicate, why inflammation matters and how the test is done.
- Vitamin B12 (cobalamin)Vitamin B12 is needed for red blood cells and nerve function. Learn what a B12 blood test shows, who is at risk of low levels and what affects results.
- Vitamin D (25-hydroxyvitamin D)The 25-hydroxyvitamin D test is the standard way to check vitamin D status. Learn what the result means, how units differ and what affects levels.
Thyroid
- Free T3 (free triiodothyronine)T3 is the most active thyroid hormone. When a T3 or free T3 test is ordered, how it adds to TSH and T4, and why it is not a routine first-line test.
- Free T4 (free thyroxine)Free T4 is the unbound, active share of the main thyroid hormone. What a free T4 blood test shows, how it is read together with TSH, and what can affect it.
- Thyroid antibodies (TPO and thyroglobulin antibodies)Thyroid antibody tests look for an immune reaction against the thyroid. What TPO and thyroglobulin antibodies indicate and how they relate to Hashimoto's and Graves' disease.
Blood count
- HemoglobinHemoglobin carries oxygen in red blood cells. What a hemoglobin test measures, what low or high values can point to, and how it fits into a complete blood count.
- Platelet countPlatelets help blood clot. What a platelet count measures, what low or high counts can mean, and how the test fits into a complete blood count.
- White blood cell count (WBC)White blood cells are part of the immune system. What the WBC count and differential show, and common reasons a count may be higher or lower.
Electrolytes
- MagnesiumMagnesium is a mineral needed for muscles, nerves and heart rhythm. What a magnesium blood test shows and why a normal result does not always rule out low body stores.
- PotassiumPotassium is an electrolyte essential for heart and muscle function. What a potassium blood test shows and common causes of high or low levels.
About LON6EVITY. A longevity and prevention platform that keeps your biomarkers, screenings and health history in one place, shows trends over time and prepares doctor-ready reports. How it works
Understand your biomarkers in context
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