Sionnach Health

Blood Test Library

Friendly, plain-language explanations of common lab markers. Tap any card to learn more.

Full blood count

Haemoglobin

Measures the oxygen-carrying protein in red blood cells.

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Full blood count

Red blood cell count

Measures the number of red blood cells in the blood.

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Full blood count

Haematocrit

Measures the proportion of blood made up by red blood cells.

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Full blood count

MCV

Measures the average size of red blood cells.

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Full blood count

MCH (Mean corpuscular haemoglobin)

Measures the average amount of haemoglobin inside each red blood cell.

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Full blood count

MCHC

Measures the average concentration of haemoglobin in red blood cells.

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Full blood count

RDW

Measures variation in the size of red blood cells.

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Full blood count

White blood cell count

Measures the number of white blood cells in the blood.

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Full blood count

Neutrophils

Measures a type of white blood cell that helps fight infection.

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Full blood count

Lymphocytes

Measures a type of white blood cell involved in immune responses.

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Full blood count

Platelets

Measures the cells that help blood clot.

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Iron and vitamins

Ferritin

Measures the body’s iron stores.

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Iron and vitamins

Serum iron

Measures the amount of iron circulating in the blood.

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Iron and vitamins

Transferrin

Measures the main protein that carries iron in the blood.

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Iron and vitamins

Transferrin saturation

Measures how much iron is bound to transferrin.

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Iron and vitamins

Total iron-binding capacity

Measures the blood’s capacity to bind iron with transferrin.

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Iron and vitamins

Folate

Measures a B vitamin needed for red blood cell production.

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Iron and vitamins

Vitamin B12

Measures a vitamin important for nerves and red blood cells.

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Iron and vitamins

Active B12

Measures the active form of vitamin B12 in the blood.

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Iron and vitamins

Vitamin D

Measures a vitamin important for bone and muscle health.

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Iron and vitamins

Magnesium

Measures an essential mineral involved in many body processes.

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Iron and vitamins

Calcium

Measures a mineral important for bones, muscles, and nerves.

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Kidney function

Creatinine

Measures a waste product used to estimate kidney function.

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Kidney function

eGFR

Estimates how well the kidneys filter blood.

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Kidney function

Urea

Measures a waste product made when the body breaks down protein.

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Kidney function

Sodium

Measures the level of sodium in the blood.

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Kidney function

Potassium

Measures the level of potassium in the blood.

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Kidney function

Chloride

Measures the level of chloride in the blood.

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Kidney function

Bicarbonate

Measures the blood’s buffering substance that helps balance acidity.

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Kidney function

Uric acid

Measures a waste product made when the body breaks down purines.

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Kidney function

Albumin-to-creatinine ratio

Measures how much albumin is being lost in the urine.

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Liver function

ALT

Measures an enzyme released when liver cells are injured.

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Liver function

AST

Measures an enzyme found in the liver and other tissues.

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Liver function

ALP

Measures an enzyme linked to the liver and bones.

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Liver function

GGT

Measures an enzyme linked to the liver and bile ducts.

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Liver function

Bilirubin

Measures a pigment made when red blood cells are broken down.

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Liver function

Albumin

Measures the main protein made by the liver.

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Liver function

Total protein

Measures the total amount of protein in the blood.

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Thyroid

TSH

Measures thyroid-stimulating hormone from the pituitary gland.

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Thyroid

Free T4

Measures the active thyroid hormone that circulates freely.

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Thyroid

Free T3

Measures the active form of thyroid hormone in the blood.

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Thyroid

Thyroid peroxidase antibodies

Measures antibodies linked to autoimmune thyroid disease.

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Thyroid

Thyroglobulin antibodies

Measures antibodies linked to thyroid tissue inflammation.

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Diabetes

HbA1c

Measures average blood sugar over the last few months.

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Diabetes

Fasting glucose

Measures blood sugar after a period without eating.

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Diabetes

Random glucose

Measures blood sugar at any time of day.

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Diabetes

Insulin

Measures the hormone that helps move glucose into cells.

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Cholesterol

Total cholesterol

Measures all cholesterol in the blood.

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Cholesterol

LDL cholesterol

Measures the main cholesterol fraction often called bad cholesterol.

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Cholesterol

HDL cholesterol

Measures the cholesterol fraction often called good cholesterol.

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Cholesterol

Triglycerides

Measures a type of fat in the blood.

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Cholesterol

Non-HDL cholesterol

Measures cholesterol carried in potentially harmful particles.

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Cholesterol

Total cholesterol-to-HDL ratio

Compares total cholesterol with the protective HDL fraction.

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Cholesterol

Lipoprotein(a)

Measures a cholesterol-carrying particle linked to inherited risk.

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Cholesterol

ApoB

Measures the main protein in many cholesterol-carrying particles.

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Inflammation

CRP

Measures a marker of inflammation in the body.

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Inflammation

ESR

Measures how quickly red blood cells settle in a sample.

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