Empty test tubes with blue caps in a laboratory rack

Blood test glossary: what each marker means

The abbreviations on a blood test report, in plain words: what each marker measures, what it is used for and what can push it up or down. It explains the words, not your result.

Blood sugar

HbA1c · Glycated haemoglobin: HbA1c shows the average amount of sugar in your blood over the past 2-3 months. It is used to check for and monitor diabetes, a condition where the body has trouble regulating blood sugar. It is useful for screening for type 2 diabetes, and for people with diabetes it is the best way to see how well blood sugar is managed.; Watch the video· 30 seconds · AI voice
HbA1c
Glucose: The level of sugar in your blood. It is used to check for diabetes, to monitor blood sugar in people with diabetes, and to see how well the body processes sugar. High levels may indicate diabetes; low levels may suggest hypoglycaemia.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Cholesterol and heart

Total cholesterol: The total amount of cholesterol in your blood, a waxy substance the body needs. Too much can lead to plaque building up in the arteries, so this marker helps assess the risk of heart disease.; Before the sample: You might be asked not to eat for up to 12 hours before a cholesterol test (NHS).; Watch the video· 34 seconds · AI voice
Cholesterol: LDL, HDL and triglycerides
LDL · Low-density lipoprotein cholesterol: Low-density lipoprotein (LDL) cholesterol is often called 'bad' cholesterol. Too much of it can build up in the walls of the arteries, so it is one of the main markers used to assess the risk of heart disease. It is usually calculated from the other results of a cholesterol profile.; Watch the video· 34 seconds · AI voice
Cholesterol: LDL, HDL and triglycerides
HDL · High-density lipoprotein cholesterol: Often called 'good' cholesterol, HDL picks up excess cholesterol from the blood vessels and takes it back to the liver. A higher HDL suggests a lower risk of heart problems, while a low level may mean a higher risk of heart disease.; Watch the video· 34 seconds · AI voice
Cholesterol: LDL, HDL and triglycerides
Non-HDL · Non-HDL cholesterol: Non-HDL cholesterol is all the cholesterol in your blood that is not the 'good' HDL kind, including LDL, often called 'bad' cholesterol. It helps assess the risk of heart disease, as too much of this cholesterol can raise that risk.; Watch the video· 34 seconds · AI voice
Cholesterol: LDL, HDL and triglycerides
Triglycerides: A type of fat in the blood that the body uses for energy. It is usually measured with a cholesterol panel, and high levels, linked to factors such as diet, weight, smoking and inactivity, can raise the risk of heart disease and stroke.; Before the sample: You might be asked not to eat for up to 12 hours before a cholesterol test (NHS).; Watch the video· 34 seconds · AI voice
Cholesterol: LDL, HDL and triglycerides
TC:HDL · Total cholesterol to HDL ratio: The ratio between your total cholesterol and your HDL cholesterol, often called 'good' cholesterol because it helps remove cholesterol from the arteries. This ratio is used to help assess the risk of heart disease.; Watch the video· 34 seconds · AI voice
Cholesterol: LDL, HDL and triglycerides
Lp(a) · Lipoprotein (a): Lipoprotein (a) is a combination of proteins and fats that can build up in the arteries. It helps assess the risk of heart disease and stroke, and because high levels can run in families it is particularly useful for people with a family history.
ApoB · Apolipoprotein B: Apolipoprotein B is a protein in LDL, VLDL and chylomicrons that helps carry cholesterol and triglycerides around the body. Measuring it helps assess cardiovascular risk and monitor cholesterol lowering treatment. A high level is associated with increased risk.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Inflammation and muscle

CRP · C-reactive protein: C-reactive protein (CRP) is made by the liver in response to inflammation. It can rise with an infection, an injury or an inflammatory condition. It is a general signal: on its own it does not show where the inflammation is or what is causing it.; Watch the video· 30 seconds · AI voice
CRP
hs-CRP · High-sensitivity C-reactive protein: C-reactive protein (CRP) is made by the liver in response to inflammation. The high sensitivity version can pick up even small amounts. It helps monitor inflammation, track how a condition is progressing or how well treatment works, and high levels have been linked to increased cardiovascular risk.; Watch the video· 30 seconds · AI voice
CRP
CK · Creatine kinase: An enzyme found mainly in the muscles and heart, released into the blood when muscle is injured, including after strenuous exercise. It helps assess muscle damage and recovery, and can help tell whether muscle pain or weakness comes from overexertion or something else.; Before the sample: Hard training in the days before the sample can raise CK, so it helps to note what exercise you did when you share the result.; Watch the video· 32 seconds · AI voice
CK, creatine kinase

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Thyroid

TSH · Thyroid stimulating hormone: Thyroid stimulating hormone (TSH) is made by the pituitary gland and regulates the thyroid, which controls your metabolism. Levels that are too high or too low can point to an underactive or overactive thyroid, which may cause tiredness, weight change, hair loss or mood changes.; Watch the video· 34 seconds · AI voice
TSH and free T4
FT4 · Free thyroxine (free T4): Free T4 is the part of thyroxine not bound to proteins in the blood. Thyroxine is made by the thyroid gland and helps regulate metabolism, energy and growth. Measuring it helps check whether the thyroid is making too much or too little hormone. Thyroid problems can cause tiredness, weight changes, mood swings and difficulty concentrating.; Watch the video· 34 seconds · AI voice
TSH and free T4
FT3 · Free triiodothyronine (free T3): Free T3 (triiodothyronine) is a thyroid hormone that helps regulate metabolism, energy levels and body temperature. It helps show whether the thyroid is overactive or underactive; high levels may come with weight loss, a fast heartbeat and anxiety.
Anti-TPO · Thyroid peroxidase antibodies: Thyroid peroxidase antibodies (anti-TPO) are made by the immune system. In autoimmune conditions their amount rises and they attack healthy thyroid cells, so the test helps look into thyroid disorders and is an indicator of autoimmune conditions such as Hashimoto's.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Liver

ALT · Alanine aminotransferase: Alanine aminotransferase (ALT) is a liver enzyme. When the liver is inflamed or damaged it releases ALT into the blood, so higher levels may point to liver conditions such as hepatitis or fatty liver, or to the effect of some medicines or alcohol on the liver.; Watch the video· 27 seconds · AI voice
Liver: ALT and GGT
GGT · Gamma-glutamyl transferase: Gamma GT (GGT) is an enzyme found mainly in the liver, and also in the pancreas and kidneys. Measuring it is commonly used to check liver health. When the liver is not working properly, GGT can rise. High levels may point to liver problems or alcohol use, and can also be seen with other conditions.; Watch the video· 27 seconds · AI voice
Liver: ALT and GGT
ALP · Alkaline phosphatase: An enzyme found in tissues such as the liver, bones and intestines. It helps check and monitor liver and bone conditions, such as hepatitis or osteoporosis, and how well their treatment is working.
Bilirubin: Bilirubin is a yellow pigment produced when red blood cells break down; the liver helps remove it. Measuring it is commonly used to check liver health. If the liver is not working well, the level can rise, and high levels can cause yellowing of the skin and eyes (jaundice).
Albumin: Albumin is a protein in the blood that carries substances such as hormones, vitamins and medicines around the body. It is commonly used to assess the liver and kidneys. A lower level can be linked to liver or kidney problems, poor nutrition or inflammation. It is often part of a routine check-up.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Kidneys and salts

Creatinine: A waste product made by the muscles and normally filtered out by the kidneys. It shows how well the kidneys are working: a high level may point to the kidneys not filtering as well. It is also used to follow kidney conditions and adjust some medicine doses.; Watch the video· 32 seconds · AI voice
Kidneys: eGFR and creatinine
eGFR · Estimated glomerular filtration rate: The estimated glomerular filtration rate (eGFR) shows how well the kidneys are filtering the blood and removing waste. It is calculated from blood creatinine along with age, sex and body size. It is mainly used to screen for and monitor kidney disease.; Watch the video· 32 seconds · AI voice
Kidneys: eGFR and creatinine
Urea: Urea is a waste product made when the body breaks down protein, and healthy kidneys filter it out into the urine. It is commonly used to check how well the kidneys are working, since urea can build up in the blood when they are not.
Na · Sodium: Sodium is an essential mineral that helps keep the body's fluids in balance and is important for nerve and muscle function. A high level may suggest dehydration, kidney problems or the effect of certain medicines, and a low level may be linked to drinking a lot of fluid, hormonal imbalance or kidney or liver conditions.
Uric acid (urate): Uric acid is a waste product made when the body breaks down certain foods, especially those high in purines. Measuring it is commonly used to check and monitor gout, a type of arthritis where uric acid crystals build up in the joints. It can also help monitor treatment and conditions such as kidney disease.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Full blood count

Hb · Haemoglobin: The protein in red blood cells that carries oxygen from the lungs to the rest of the body. A low level can point to anaemia, which may bring tiredness, weakness or breathlessness, while a high level may suggest polycythaemia, where the blood becomes thicker.; Watch the video· 34 seconds · AI voice
Full blood count
Hct · Haematocrit: The proportion of your blood made up of red blood cells, part of a full blood count. Low values can suggest anaemia; high values may indicate polycythaemia, where the body makes too many red cells.; Watch the video· 34 seconds · AI voice
Full blood count
MCV · Mean cell volume: The average size of your red blood cells, which carry oxygen around the body. Cells larger or smaller than usual can be a sign of certain types of anaemia or other health conditions.; Watch the video· 34 seconds · AI voice
Full blood count
WBC · White cell count: The white cell count measures the number of white cells in your blood. White cells are part of the immune system: the count can go up with an infection or inflammation and down with some medicines or conditions.; Watch the video· 34 seconds · AI voice
Full blood count
PLT · Platelet count: Platelets are tiny blood cells that help form clots to stop bleeding. Too few platelets can lead to easy bruising and bleeding, while too many can raise the chance of clots in veins or arteries. Doctors use the count to monitor a range of conditions.; Watch the video· 34 seconds · AI voice
Full blood count

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Iron

Ferritin: Ferritin stores iron, an essential mineral. Measuring it shows whether you have too much or too little iron. A high level may point to excess iron; a low level may suggest iron deficiency, which can cause tiredness, weakness and difficulty concentrating. It helps check and monitor iron overload (haemochromatosis) and iron deficiency anaemia.; Watch the video· 30 seconds · AI voice
Ferritin
Fe · Serum iron: Iron is an essential mineral that helps the body make red blood cells and carry oxygen. Measuring it checks for iron deficiency or iron overload. Low iron can lead to iron deficiency anaemia, with tiredness, weakness, pale skin and breathlessness; a high level may point to haemochromatosis, where the body absorbs too much iron from food.
TSAT · Transferrin saturation: Shows how much iron is in your blood and how well it is being carried to your organs and tissues. Low levels may mean the body is not getting or absorbing enough iron, while high levels can suggest iron overload, as in haemochromatosis.
TIBC · Total iron-binding capacity: Total iron binding capacity (TIBC) measures how much iron the proteins in your blood can carry, showing how well the body transports and stores iron. Iron is needed to make red blood cells. Together with other blood tests, it helps assess iron levels and look into iron deficiency anaemia or iron overload.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Vitamins and minerals

25(OH)D · Vitamin D (25-hydroxyvitamin D): Vitamin D helps the body absorb calcium and keep bones strong. It comes from food and supplements, or is made in the skin with sunlight. Low vitamin D can lead to weak bones and muscle weakness and can affect the immune system. Measuring it identifies deficiency and helps monitor conditions that affect fat absorption, such as Crohn's disease.; Watch the video· 29 seconds · AI voice
Vitamin D
B12 · Vitamin B12: A vitamin needed to form red blood cells, repair tissue and keep nerves healthy. It comes mainly from meat, fish, milk and eggs, so it is particularly relevant on a plant-based diet. Low levels can bring anaemia, tiredness, weakness and nerve symptoms, and pregnancy complications in women.; Watch the video· 35 seconds · AI voice
Vitamin B12
Active vitamin B12: Active vitamin B12 is the form the body can use. Vitamin B12 is essential for making red blood cells, DNA and a healthy nervous system. This shows whether you have too little or too much. Low levels can lead to anaemia, tiredness and weakness, and can affect nerves, mood and memory; high levels may need further investigation.; Watch the video· 35 seconds · AI voice
Vitamin B12
B9 · Folate: Folate, also known as vitamin B9, is a nutrient needed for DNA synthesis, red blood cell production and cell division. Low levels can point to a deficiency, linked to tiredness, weakness, pale skin and poor concentration, and the test is also used to check levels during pregnancy.
Mg · Magnesium: Magnesium is an essential mineral that supports nerve and muscle function, a steady heart rhythm, the immune system and bones. It is often checked with muscle weakness, tiredness, an irregular heartbeat or tingling, and to monitor supplements or electrolyte balance.
Ca · Adjusted calcium: Calcium level corrected for albumin, a blood protein. Calcium matters for bones, muscles and nerves. Levels too high or too low can bring muscle weakness, tiredness or bone pain, and the result helps monitor conditions affecting calcium, such as kidney or thyroid disorders.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Hormones

FSH · Follicle stimulating hormone: Follicle stimulating hormone (FSH) comes from the pituitary gland. In women it drives follicle growth and the menstrual cycle; in men it supports sperm production. Levels help assess fertility and reproductive health, including menopause.
LH · Luteinising hormone: Luteinising hormone (LH) is made by the pituitary gland and is key to sexual development and function. In women it regulates the menstrual cycle and triggers ovulation; in men it stimulates testosterone production. Testing can help assess fertility.
E2 · Oestradiol: Oestradiol is a form of oestrogen. It shapes female reproductive tissues and the menstrual cycle, and also supports bone, heart and brain health in women and men. Levels help assess fertility, menstrual changes, menopause and hormone therapy.
Progesterone: A steroid hormone made mainly by the ovaries, with smaller amounts from the adrenal glands and testes. In women it regulates the cycle, confirms ovulation and supports early pregnancy, with levels varying by cycle stage, pregnancy, menopause and medication. In men it helps produce other hormones.
AMH · Anti-Müllerian hormone: A reproductive hormone made by developing follicles in the ovaries. It is used to help assess fertility and to indicate peri-menopausal and menopausal status in women.
PRL · Prolactin: Prolactin is a hormone made by the pituitary gland that plays a key role in breastfeeding and reproduction. It may be checked in women with irregular or absent periods, fertility questions or breast milk problems, in men, and to look into the pituitary gland.
Testosterone: Testosterone is an important sex hormone for men and women, made in the testicles in men and in small amounts in the ovaries in women. In men, too little can cause tiredness, low mood and reduced muscle mass; in women, too much can cause acne, excess hair and irregular periods. The best time to give a sample is between 7am and 10am.
SHBG · Sex hormone binding globulin: A protein made by the liver that binds sex hormones such as testosterone and oestrogen in the blood. It helps assess hormone balance, for example in PCOS, hypogonadism or excess androgens, can reflect liver function, and helps follow hormone replacement therapy. It is read with other hormone tests.
FAI · Free androgen index: Estimates the androgens, such as testosterone, that are not bound to proteins in the blood. Androgens help with muscle mass and sex drive, among other roles. The index helps look into imbalances such as polycystic ovary syndrome (PCOS) and helps monitor hormone therapy in transgender people.
Cortisol: Cortisol is a hormone made by the adrenal glands. It helps regulate the response to stress, blood sugar and the immune system. Measuring it helps assess how well the adrenal glands are working and whether cortisol production is in balance, and can help investigate conditions such as Cushing's syndrome or Addison's disease.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Prostate

PSA · Prostate specific antigen: Prostate specific antigen (PSA) is a protein made by the prostate. Higher levels can be linked to prostate cancer but also to an enlarged prostate or infection. It helps assess risk and decide on further tests; it cannot confirm cancer on its own.; Before the sample: For 48 hours before a PSA test, the NHS advises avoiding ejaculation, anal sex and exercise that leaves you out of breath, such as cycling, because they can raise the level. It is worth talking it through with a doctor first, to understand what the result can and cannot tell you; you do not need a referral to order it.; Watch the video· 37 seconds · AI voice
PSA
fPSA · Free prostate specific antigen: PSA is a protein made by the prostate gland. Free PSA is the part not bound to other proteins in the blood. The free PSA percentage helps tell benign conditions apart from prostate cancer: a higher percentage may suggest lower risk. Raised PSA can also come from an enlarged or inflamed prostate.; Watch the video· 37 seconds · AI voice
PSA

Reference ranges vary; take your results to a doctor you trust, such as your GP.

Immunity

IgG · Measles antibodies (IgG): IgG antibodies to the measles virus, used to check your immunity status against measles.
IgG · Mumps antibodies (IgG): Measures IgG antibodies to the mumps virus, which the body makes after infection or vaccination. It shows whether someone has immunity to mumps, a contagious infection that mainly affects the salivary glands and causes swelling around the jaw.
IgG · Rubella antibodies (IgG): IgG antibodies to rubella. A high level means you are immune; a low or absent level means you are not and may need to take precautions. This is especially important in pregnancy.

Reference ranges vary; take your results to a doctor you trust, such as your GP.

If you feel very unwell, call 999 in an emergency or NHS 111 for urgent advice.

Not sure which test? See the check-up guide

Sources: NHS: Blood tests · NHS: High cholesterol, getting tested · NHS: PSA test

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