Health Knowledge Hub
Plain-English explainers for every blood-test marker. Written for UK patients, reviewed by clinicians. Each article shows what the marker is, what high or low values can mean, and the questions worth raising with your GP.
Allergy Evaluation
(1 article)Bone Health
(1 article)Diabetes Health
(4 articles)Digestive Health
(2 articles)Full Blood Count
(13 articles)Basophil Count
Type of white blood cell involved in allergic reactions.
2 min read
Eosinophil Count
Type of white blood cell associated with allergies and parasitic infections.
2 min read
Haematocrit
Proportion of blood made up of red blood cells.
2 min read
Haemoglobin
Oxygen-carrying protein in red blood cells.
2 min read
Lymphocyte Count
White blood cells central to immune defence.
2 min read
Mean Cell Haemoglobin (MCH)
Average haemoglobin content per red blood cell.
2 min read
Mean Cell Haemoglobin Concentration (MCHC)
Average haemoglobin concentration in a given volume of red blood cells.
2 min read
Mean Cell Volume (MCV)
Average size of red blood cells.
2 min read
Monocyte Count
White blood cells that engulf bacteria and dead cells.
2 min read
Neutrophil Count
Frontline white blood cells against bacterial infection.
2 min read
Platelet Count
Cells that help blood clot.
2 min read
Red Blood Cell Count
Number of red blood cells, which carry oxygen around the body.
2 min read
White Blood Cell Count
Total white blood cell count — overall immune-system marker.
2 min read
Heart Health
(12 articles)Apolipoprotein A-I
Main protein of HDL; protective against heart disease.
2 min read
Apolipoprotein B
Main protein of atherogenic ('bad') lipoproteins.
2 min read
Apolipoprotein B / A-I Ratio
Atherogenic-to-protective lipoprotein ratio.
2 min read
Cardiovascular Risk Score
10-year heart-disease risk estimate.
2 min read
HDL Cholesterol
'Good' cholesterol — protective; higher is better.
2 min read
High Sensitivity C-Reactive Protein (hs-CRP)
Sensitive marker of low-grade inflammation; cardiovascular risk indicator.
2 min read
LDL Cholesterol
'Bad' cholesterol — high values raise heart-disease and stroke risk.
2 min read
Lipoprotein (a)
Genetically-determined cardiovascular risk marker.
2 min read
Small LDL Cholesterol
Particularly atherogenic small dense LDL particles.
2 min read
Total Cholesterol
Total fat-carrying particles in blood; high values raise heart-disease risk.
2 min read
Total Cholesterol / HDL Cholesterol Ratio
Composite cardiovascular risk indicator.
2 min read
Triglycerides
Most abundant fat in blood; high values relate to metabolic syndrome.
2 min read
Infection & Inflammation
(7 articles)Antistreptolysin O (ASO)
Antibody against streptococcal bacteria.
2 min read
C-Reactive Protein (CRP)
General marker of inflammation or infection.
2 min read
Complement Component 3 (C3)
Immune-system protein; consumed in some autoimmune diseases.
2 min read
Complement Component 4 (C4)
Immune-system protein; pattern with C3 helps autoimmune diagnosis.
2 min read
Immunoglobulin A (IgA)
Antibody class that defends mucosal surfaces.
2 min read
Immunoglobulin G (IgG)
Most abundant antibody class; principal long-term immunity.
2 min read
Immunoglobulin M (IgM)
First antibody made in response to a new infection.
2 min read
Iron Status
(5 articles)Ferritin
Stored iron — a key marker of iron deficiency.
2 min read
Iron
Essential mineral for red blood cell formation.
2 min read
Total Iron Binding Capacity (TIBC)
Capacity of blood to transport iron.
2 min read
Transferrin
Protein that transports iron in the blood.
2 min read
Transferrin Saturation
Percentage of transferrin carrying iron.
2 min read
Kidney Health
(11 articles)Calcium (adjusted)
Key mineral for bones, muscles, and nerves.
2 min read
Chloride
Electrolyte that helps regulate fluid balance.
2 min read
Creatinine
Waste product filtered by the kidneys; marker of kidney function.
2 min read
Cystatin C
Alternative kidney function marker, less affected by muscle mass.
2 min read
Estimated Glomerular Filtration Rate (eGFR)
Calculated kidney filtration rate; primary kidney function marker.
2 min read
Magnesium
Essential mineral for muscle, nerve, and heart function.
2 min read
Phosphate
Mineral important for bones and energy metabolism.
2 min read
Potassium
Critical electrolyte for heart rhythm.
2 min read
Sodium
Primary electrolyte for fluid balance and nerve function.
2 min read
Urea
Nitrogen waste product cleared by the kidneys.
2 min read
Uric Acid
Breakdown product of purines; high values cause gout.
2 min read
Liver Health
(6 articles)Alanine Aminotransferase (ALT)
Liver enzyme released when liver cells are damaged.
2 min read
Albumin
Major blood protein made by the liver; nutritional and liver-function marker.
2 min read
Alkaline Phosphatase (ALP)
Enzyme from liver and bone; raised in bile-duct or bone disease.
2 min read
Aspartate Aminotransferase (AST)
Enzyme from liver, heart, and muscle; marker of cell damage.
2 min read
Gamma-Glutamyltransferase (GGT)
Sensitive marker of liver and bile-duct disease.
2 min read
Total Bilirubin
Yellow pigment from red-cell breakdown; elevated in jaundice.
2 min read
Male Hormonal Health
(3 articles)Muscle & Joint Health
(2 articles)Nutritional Health
(4 articles)Folic Acid
B-vitamin essential for red-blood-cell formation and DNA synthesis.
2 min read
Total Antioxidant Status (TAS)
Combined antioxidant capacity of the blood.
2 min read
Vitamin B12
Vitamin needed for nerve and red-blood-cell health.
2 min read
Vitamin D
Vitamin essential for bones, immunity, and many other functions.
2 min read
Pancreatic Health
(2 articles)Personal Health Measurements
(7 articles)Body Mass Index (BMI)
Weight-to-height ratio; obesity and underweight indicator.
2 min read
Diastolic Blood Pressure
Pressure when the heart rests between beats.
2 min read
Oxygen Saturation
Percentage of haemoglobin carrying oxygen.
2 min read
Pulse
Resting heart rate.
2 min read
Systolic Blood Pressure
Pressure when the heart contracts.
2 min read
Waist / Hip Ratio
Ratio of waist-to-hip; central-obesity indicator.
2 min read
Waist Circumference
Central fat measurement; metabolic-syndrome marker.
2 min read
Prostate Health
(2 articles)Thyroid Health
(5 articles)Anti-Thyroglobulin Antibody (Anti-Tg)
Antibody linked to autoimmune thyroid disease.
2 min read
Anti-Thyroid Peroxidase Antibody (Anti-TPO)
Most common antibody in autoimmune thyroid disease.
2 min read
Free Thyroxine (FT4)
Active thyroid hormone available to tissues.
2 min read
Free Tri-iodothyronine (FT3)
Most active thyroid hormone.
2 min read
Thyroid Stimulating Hormone (TSH)
Pituitary signal that controls the thyroid gland.
2 min read