Compare our tests and biomarkers

A raised level is linked with a higher risk of heart disease, stroke and blood clots, and usually points to a shortfall in B vitamins that is simple to correct. Useful if heart disease runs in your family or you eat little animal protein.

A higher Omega-3 Index is linked with better heart, brain and joint health; below 4% is considered high risk and above 8% optimal. Useful if you rarely eat oily fish, want to check whether a supplement is working, or eat a lot of processed food.

A raised level can show strain on the heart before any symptoms appear, and is the standard test used to look for heart failure. Useful if you are breathless or tire more easily than you used to, have high blood pressure, or have heart disease in your family. It also rises naturally with age and with reduced kidney function.

It shows the effect of a change in diet, exercise or medication weeks before HbA1c does, which covers around three months. Useful if you have recently changed something and want to see whether it is working, or where HbA1c is unreliable, such as with some forms of anaemia or in pregnancy.

Insulin normally keeps fat stores in check, so a persistently raised level is an early sign of insulin resistance and can appear before glucose or HbA1c drift out of range. Useful if you have prediabetes, carry weight around your middle, or have type 2 diabetes in your family.

A low level can reflect poor nutrition, protein being lost through the kidneys, or reduced production by the liver. A high level usually reflects dehydration or inflammation, and occasionally excess antibody production. Useful as a general check alongside your kidney and liver results.

A low level suggests the blood is becoming too acidic, which can happen with kidney disease, uncontrolled diabetes or severe diarrhoea. A high level can reflect prolonged vomiting, some diuretics or a breathing problem. Useful if a kidney result is borderline or you take medication that affects the kidneys.

Small amounts of albumin in urine can appear years before kidney filtering declines, which is why this is the standard annual check for anyone with diabetes or high blood pressure. A raised ratio is an early, treatable sign of kidney and blood vessel damage.

It is released whenever cells break down, so a raised level can point to injury to the liver, heart, muscle or red blood cells. On its own it does not say where the damage is, so it is read alongside your other liver and muscle results to help locate the source.

Because it sits deep inside the cell and is barely found elsewhere, a raised level is a more specific sign of liver cell injury than ALT or AST, which are also found in muscle. Useful if a liver enzyme has come back raised and you want to know whether the liver itself is the cause.

Comparing direct with total bilirubin shows whether a raised level comes from the liver and bile ducts or from red blood cells breaking down too fast. Useful if your total bilirubin is raised, including the common and harmless Gilbert’s syndrome, which this test helps confirm.

A raised level is an early sign that the liver is struggling to recapture bile acids from the blood, and can show reduced liver function or impaired bile flow before other tests change. Useful if you have itching, fatty liver, or a liver result that needs a closer look.

A high level points to ongoing inflammation, infection or, less commonly, excess antibody production. A low level can reflect a weakened immune system or reduced liver production. Useful as a general screen alongside your liver and inflammation results.

A raised level points to damage to muscle or liver tissue and is most often used to investigate muscle weakness, pain or inflammation. It can stay raised after creatine kinase has returned to normal, which makes it useful in some muscle conditions.

A low level can point to alpha-1 antitrypsin deficiency, one of the most common inherited conditions in people of European descent and one that most people with it never know about. It raises the risk of lung and liver disease, both of which can be reduced once you know. Useful if lung or liver disease runs in your family, or if you have unexplained liver results.

A low level can point to Wilson’s disease, an inherited problem with copper handling that is treatable if caught early, or to severe copper deficiency. It rises with inflammation, infection, pregnancy and oestrogen use. Useful if you have unexplained liver results, tremor or movement symptoms, or Wilson’s disease in your family.

A negative result makes coeliac disease very unlikely, and that is the test’s real value: it can rule the condition out even if you have already stopped eating gluten, when the antibody test no longer works. A positive result shows susceptibility only. Useful if you have cut out gluten and cannot tell whether it was the problem, or coeliac disease runs in your family.

A low level can reflect a poor intake or trouble absorbing fat, and fading night vision is one of the earliest signs. A high level usually comes from over-supplementation and can harm the liver over time. Useful if you take a high-dose supplement, have a gut condition that affects fat absorption, or notice dry eyes or skin.

Your body holds only a couple of weeks’ reserve, so a low level can develop quickly with poor intake, regular heavy drinking or malabsorption, including after weight-loss surgery. Useful if you drink regularly, have had bariatric surgery, or have unexplained tiredness, tingling or poor concentration.

A low level can reflect a low intake of dairy, eggs, meat and green vegetables, or increased needs in pregnancy or heavy training, and it holds back the other B vitamins too. Useful if you follow a vegan diet, train hard, or get cracked lips or sore eyes.

Your body can make some niacin from the amino acid tryptophan, so deficiency is uncommon with a varied diet, but it can occur with poor intake, heavy drinking or malabsorption. Useful if your diet is restricted or you take a supplement and want to check the level.

It is found in almost every food, so a low level is rare and usually reflects severe malnutrition or malabsorption. Useful mainly as part of a full B-vitamin check if your diet is very restricted.

A low level can affect mood, sleep and energy, and is more common with heavy drinking, some medications and kidney disease. A very high level from long-term supplementation can damage the nerves, causing tingling or numbness. Useful if you take a B-complex or magnesium-B6 supplement, or have low mood, poor sleep or tingling without a clear cause.

Your body cannot make or store much vitamin C, so the level reflects your recent intake of fruit and vegetables. Smoking uses it up faster. Useful if your diet is low in fresh produce, you smoke, you heal slowly, or you have low iron that is not responding to diet.

A low level is uncommon from diet alone and usually points to trouble absorbing fat or a very low-fat diet. A high level reflects supplement use. Useful if you have a gut or pancreatic condition that affects fat absorption, or take a high-dose antioxidant supplement.

Only around a fifth of the B12 in your blood is in the active form, so a normal total B12 can hide a real deficiency, which affects energy, nerves, mood and blood health. Useful if you follow a plant-based diet, take acid-reducing medication or metformin, are over 60, or have symptoms despite a normal total B12.

A low level points to a sustained shortfall, which affects red blood cell production and energy. Folate is also the most important vitamin before and in early pregnancy, where it reduces the risk of birth defects. Useful if you are planning a pregnancy, eat few green vegetables, drink regularly, or have a low serum folate and want to know whether it is a longer-term problem.

A low level reflects a low intake of fruit and vegetables or trouble absorbing fat; a high level reflects a very high intake or supplement use. Because the body converts only what it needs, food sources never cause vitamin A toxicity. Useful as a marker of how much fresh produce you actually eat.

A low level can weaken immunity, slow healing and dull your sense of taste or smell, and is more common with plant-based diets, heavy drinking and gut conditions. Useful if you get frequent infections, heal slowly, have hair loss or skin problems, or follow a vegan diet.

A low level can reflect poor intake, malabsorption or long-term high-dose zinc supplements, which block copper uptake, and can cause anaemia and nerve symptoms. A high level is seen with inflammation, pregnancy and oestrogen use. Useful if you take zinc regularly, have had bariatric surgery, or have unexplained anaemia or tingling.

A low level usually reflects a poor dietary intake, which is common where soils are low in selenium, including much of Europe. A high level usually means over-supplementation. Useful if you have a thyroid condition, follow a plant-based diet, or take a selenium supplement and want to check the dose. Two Brazil nuts a day usually cover your needs.

Deficiency is rare, so a low level usually reflects a very restricted diet or malabsorption. A raised level usually points to occupational or environmental exposure, such as welding or contaminated water. Useful if you work with metals or take a supplement containing manganese.

ESR changes slowly, so it is better at tracking long-running inflammation, such as autoimmune disease or chronic infection, than catching something acute. Useful if you have persistent aches, fatigue or recurring symptoms and your CRP is normal.

It moves in two directions: it falls when red cells are breaking down faster than normal and rises with inflammation. Useful if you have unexplained anaemia, jaundice or fatigue, or an inflammation result that needs a second angle.

Around nine in ten adults carry EBV for life without symptoms. A recent-infection pattern can explain weeks of fatigue, sore throat and swollen glands; a past-infection pattern rules it out as the cause. Useful if you have prolonged tiredness after an illness.

A positive result means past exposure; the virus then stays dormant and is kept in check by a healthy immune system. Knowing your status matters most when planning a pregnancy, since a first infection during pregnancy can affect the baby, and before some medical treatments.

A positive result can point to current or past infection. Useful if you have had a tick bite or spend time in long grass or woodland and have a spreading rash, flu-like symptoms, joint pain or unexplained fatigue. Antibodies take several weeks to develop, so timing affects how the result is read.

IgM points to a recent infection and IgG to past exposure. Around four in five Zika infections cause no symptoms, so testing is often the only way to know. Useful after travel to an affected region, especially if you or your partner are planning a pregnancy, as the virus can affect a developing baby.

IgM antibodies mean a recent or current infection; IgG means past infection or vaccination, which gives lifelong immunity. Hepatitis A never becomes a chronic infection. Useful before travel, if you are unsure whether you have been vaccinated, or after a possible exposure.

A positive result means you have been exposed to the virus at some point, and distinguishes natural infection from vaccination. Read alongside the surface antigen and surface antibody results, it shows whether an infection is current, resolved or vaccine immunity. Also relevant before some medical treatments that can reactivate a past infection.

A positive result means active infection; a negative result after positive antibodies means the infection has cleared, naturally or with treatment. Hepatitis C is now curable in more than 95% of cases with a short course of tablets, so finding it is what matters. Useful if you have ever had a positive antibody test, a blood transfusion before 1991, or a possible exposure.

Measles is one of the most contagious viruses known, and immunity from a single childhood dose can be incomplete. A negative result means vaccination is worth discussing. Useful if you cannot find your records, work in healthcare or with children, or are travelling to an area with outbreaks.

Mumps outbreaks still occur in adults whose childhood immunity has faded, and infection in adulthood is more likely to cause complications. Useful if you cannot find your records or are in a setting where outbreaks happen, such as universities or healthcare.

Rubella in early pregnancy can seriously affect a baby, so immunity matters most for anyone planning a pregnancy, when vaccination before conceiving is usually advised. Useful before pregnancy, if you cannot find your records, or if you work with children.

Most adults are immune without knowing it. A negative result matters before pregnancy, where chickenpox can affect the baby, and before any treatment that suppresses the immune system. The same virus causes shingles later in life, which is why a separate shingles vaccine exists.

A good level means you are protected. A low or absent level can mean immunity has faded or that you did not respond fully to the vaccine, and a booster may be worth discussing. Useful if you work in healthcare, travel widely, or had your vaccine course more than ten years ago.

A positive result can point to an autoimmune condition such as lupus or another connective tissue disease. Around one in eight healthy adults has a low-level positive, so the titre, the pattern and your symptoms all count. Useful if you have joint pain, rashes, mouth ulcers, dry eyes or unexplained fatigue, or autoimmune disease in your family.

A positive result can point to vasculitis, an inflammation of the small blood vessels that can affect the kidneys, lungs, sinuses and skin, and is occasionally seen with inflammatory bowel disease. Picking it up on a blood test rather than after months of symptoms protects the kidneys and lungs. Useful if you have unexplained sinus problems, blood in the urine, rashes or weight loss.

A positive result is strongly linked with primary biliary cholangitis, an autoimmune condition of the liver’s small bile ducts that responds well to treatment. The antibodies can appear years before symptoms, making this an unusually early warning. Useful if you have itching, fatigue, a raised ALP, or autoimmune disease in your family.

A positive result points strongly to rheumatoid arthritis and can appear years before the first joint symptoms. Finding it early allows treatment that prevents joint damage. Useful if you have joint pain or morning stiffness in the hands or feet, a positive rheumatoid factor, or rheumatoid arthritis in your family.

A positive result confirms pernicious anaemia, an autoimmune cause of B12 deficiency that needs B12 injections rather than tablets. The antibodies are missed in around half of cases, so a negative result does not rule it out. Useful if you have low B12 without an obvious dietary reason, or other autoimmune conditions.

A positive result can point to autoimmune gastritis, in which the immune system attacks the stomach lining, reducing B12 and iron absorption over time. It is found in around nine in ten people with pernicious anaemia, but also in some healthy people, so it is read alongside intrinsic factor antibodies and B12. Useful if you have low B12 or iron without a clear cause.

A raised level can point to overgrowth of the thyroid’s C-cells, including medullary thyroid cancer, a rare cancer that is easier to treat the earlier it is found. Mild rises also occur with kidney disease, smoking and some medications. Useful if you have a thyroid nodule, or medullary thyroid cancer or MEN2 in your family.

Changes in TBG shift your total thyroid hormone levels without changing the free hormone your cells use, which can make thyroid results confusing. It rises with oestrogen (pregnancy, the pill, HRT) and falls with liver disease, kidney protein loss and some steroids. Useful if your thyroid results have looked inconsistent, or you have started or stopped hormonal contraception or HRT.

It rises during illness, physical stress and very low-calorie dieting, when the body deliberately slows metabolism to conserve energy. Useful if your TSH and T4 are normal but you still have symptoms like fatigue, weight change or feeling cold, or you are in a sustained calorie deficit.

A rising level can point to liver cancer, and it is the standard marker used alongside ultrasound to monitor people with cirrhosis or hepatitis B. It also rises with hepatitis, fatty liver, pregnancy and some benign conditions. Its value is as a personal baseline and a trend over time.

A rising level can point to bowel and some other cancers and is mainly used to monitor known disease. Smoking can roughly double it, and it also rises with inflammatory bowel disease, liver disease and lung conditions. Its value is as a personal baseline read against your own earlier results.

It is mainly used to track treatment response in known breast cancer, where a rising level can signal a change before a scan does. It also rises with benign breast conditions, liver disease and pregnancy. Its value is as a personal baseline read against your own earlier results.

A rising level can point to cancers of the pancreas and bile ducts and is used mainly to monitor known disease. It also rises with gallstones, pancreatitis, liver disease and bile duct blockage. Around one in ten people cannot make CA 19-9 at all, so their result reads as normal whatever is happening.

A low level can point to adrenal insufficiency; a high level can reflect sustained stress, poor sleep, some medications or, rarely, an adrenal or pituitary condition. Useful if you feel constantly wired or exhausted, sleep badly, or have unexplained weight or blood pressure changes.

It peaks in your twenties and roughly halves by your fifties, so it is read against an age-specific range. A high level can point to PCOS or an adrenal condition; a low level can reflect adrenal insufficiency or simply ageing. Useful if you have irregular periods, acne or excess hair, or low energy and libido.

A low level can point to growth hormone deficiency, which affects muscle, bone and energy; a high level reflects excess growth hormone. Useful if you have unexplained loss of muscle or bone strength, poor recovery from exercise, or want to see the effect of training, sleep and nutrition on your growth hormone axis.

A lower level suggests a smaller ovarian reserve, which can affect how long you have to conceive naturally and how you might respond to fertility treatment. It can be tested at any point in your cycle. Useful if you are thinking about when to start a family, considering egg freezing, or have irregular periods.

It is several times more potent than testosterone, so small shifts have outsized effects. A high level is linked with male-pattern hair loss, acne and prostate enlargement; a low level can reflect reduced conversion or low testosterone itself. Useful if you are noticing hair thinning or persistent acne, or want a fuller picture alongside your testosterone.

Combined antigen and antibody testing can detect HIV within a few weeks of exposure. With modern treatment, people with HIV live full lives and cannot pass the virus on once levels are undetectable, so knowing early is what matters. Useful after a possible exposure, with a new partner, or as part of a routine check.

A positive result means a current hepatitis B infection, which often causes no symptoms for decades while damaging the liver. Effective treatment exists to keep it under control, and knowing protects your partners too. Useful if you have never been tested, were born in a region where hepatitis B is common, or have had a possible exposure.

Antibodies persist after the infection has cleared, so a positive result is always followed by a PCR test to check whether the virus is still present. Hepatitis C is curable in more than 95% of cases. Useful if you had a blood transfusion before 1991, have ever shared needles or razors, or have had a tattoo or piercing in an unregulated setting.

A raised level can point to occupational exposure, long-term use of aluminium-containing antacids, or reduced clearance when kidney function is impaired. Healthy kidneys clear almost all of the aluminium in food and cookware. Useful if you work with aluminium, take antacids regularly, or have kidney disease.

Even modest levels can affect the nervous system, blood pressure, kidneys and fertility, and children and pregnant women are most sensitive. Exposure today comes mainly from old paint, old water pipes, contaminated soil and some occupations and hobbies. Useful if you live in or are renovating a pre-1970s property, work with lead, batteries or paint, or shoot or make fishing weights.

A raised level usually reflects a high intake of large predatory fish such as tuna, swordfish and marlin, or occupational exposure, and can affect the nervous system and, in pregnancy, the baby. Smaller oily fish such as sardines and mackerel give the omega-3 benefit with far less mercury. Useful if you eat tuna or swordfish several times a week, are pregnant or planning to be, or work with mercury.

Blood group is inherited and fixed for life. It matters for transfusions and for pregnancy, where RhD-negative mothers need extra care, and is useful to have on record for travel or emergencies. Around one in seven people is RhD negative. Useful if you have never been told your type or are planning a pregnancy.