Liver function tests, often called LFTs or liver blood tests, are a group of measurements that give an indirect picture of how the liver and bile ducts are coping. This panel combines enzymes that rise when liver cells or bile ducts are under strain, bilirubin, and the proteins the liver makes.
Before you book
- Price: £70. This covers laboratory analysis and your laboratory report.
- Where: Your blood sample is taken from a vein by our team at 82 King Street, Maidstone, or at a partner clinic near you, anywhere in the UK.
- Preparation: No fasting. Avoid unaccustomed hard training in the week before.
- Results: the laboratory's report shows each result beside its reference range. We confirm the expected turnaround and any collection fee before you book.
- Optional: a written interpretation (£50) or a results consultation with Marina (£100).
After you order, we contact you to arrange your blood draw. A postal finger-prick kit may be possible for this test: please ask before ordering.
Despite the name, no single result measures liver function directly, and normal results do not rule out every liver condition. The pattern across the results, read with your history, is what matters.
What is measured
- ALT (alanine aminotransferase)
- AST (aspartate aminotransferase)
- ALP (alkaline phosphatase)
- GGT (gamma-glutamyl transferase)
- Bilirubin
- Albumin
- Total protein
- Globulin (calculated)
Useful for
- Following up a previous abnormal liver blood test
- Current figures to discuss with your GP if you drink alcohol regularly, carry excess weight or have type 2 diabetes
- A record of your liver blood tests before or alongside discussion of a new medicine or supplement with your clinician
Sample: venous blood sample. Fasting: not usually needed. Biomarkers: 8 results (7 measured, 1 calculated). Price includes: laboratory analysis and the laboratory's results report. Interpretation is optional and priced separately.
Helpful links: Compare health checks · How to prepare for a blood test · Understanding your report · All blood tests
Liver Function Blood Test
Liver cell enzymes
- ALT (measured): the more liver-specific marker of liver cell inflammation or injury.
- AST (measured): also reflects liver cell injury, but is found in muscle and red cells too. The AST to ALT relationship is used in some fibrosis scores.
Bile duct enzymes
- ALP (measured): raised in reduced bile flow, and also from bone, growth and pregnancy.
- GGT (measured): helps confirm whether a raised ALP comes from the liver; sensitive to alcohol and some medicines.
Processing and proteins
- Bilirubin (measured): reflects red cell breakdown and the liver's handling of bilirubin.
- Albumin (measured): the main protein made by the liver; also affected by inflammation, nutrition and kidney protein loss.
- Total protein (measured): albumin plus globulins.
- Globulin (calculated): total protein minus albumin. A raised globulin can reflect immune activity and may prompt further tests.
The laboratory counts this panel as 8 biomarkers. It does not include clotting tests (prothrombin time or INR), a platelet count, viral hepatitis tests or imaging.
The liver processes nutrients, makes proteins such as albumin and clotting factors, produces bile, and breaks down alcohol, medicines and old red blood cells. Liver blood tests look at three different aspects of this work.
Liver cell injury (hepatocellular pattern)
ALT and AST are enzymes inside liver cells. When cells are inflamed or damaged, more enzyme leaks into the blood. ALT is found mainly in the liver; AST is also present in muscle, heart and red blood cells, so it is less specific. A rise led by ALT and AST is described as a hepatocellular pattern, seen for example in fatty liver disease, viral hepatitis, alcohol-related liver disease and drug-induced injury.
Bile flow (cholestatic pattern)
ALP and GGT are concentrated in the cells lining the bile ducts. A rise in both together suggests cholestasis, where bile flow is reduced. ALP also comes from bone, so a raised ALP with a normal GGT often points away from the liver. GGT can be raised by alcohol and by some medicines.
Processing and synthesis
Bilirubin is the yellow pigment made when red blood cells break down; the liver processes it and excretes it in bile. Albumin is made by the liver, but it lasts around 20 days in the blood, so it changes slowly and is a non-specific marker. Globulins include antibodies made by the immune system.
British Society of Gastroenterology guidance (2018) notes that the size of a liver test abnormality is not necessarily a guide to its clinical significance, and that the specific result and clinical context matter more. Clotting tests and a platelet count, which are often needed to judge the liver's synthetic function and fibrosis risk, are not part of this panel.
Each result is shown against the laboratory's reference range. Ranges differ between laboratories, and there is debate about where the upper limit should sit: a 2017 American College of Gastroenterology guideline proposed lower healthy ALT limits than many laboratories use. A result just outside a range is common and often not significant on its own.
The 2018 British Society of Gastroenterology guideline reports that in one large UK data set around 30% of liver blood test requests contained at least one abnormal result. Most mild abnormalities need context and often a repeat test rather than alarm.
Common reasons for abnormal results without liver disease
- Hard exercise: in a study of healthy men, one hour of unaccustomed weightlifting raised AST and ALT for at least 7 days.
- Gilbert's syndrome: a common, harmless inherited condition that causes an isolated, mildly raised bilirubin. The NHS notes that intense exercise, poor sleep, alcohol and low fluid intake can bring on mild jaundice in people with it.
- Bone and growth: ALP is naturally higher in teenagers, in pregnancy and with some bone conditions. NHS pharmacy guidance suggests checking vitamin D status when ALP is raised on its own.
- Alcohol and medicines: GGT rises with alcohol and with some medicines. NHS pharmacy guidance notes that in people drinking excessively, four weeks without alcohol should bring GGT back towards normal.
- Sample handling: damage to red cells in the sample (haemolysis) can raise AST.
- Low albumin: often reflects inflammation, recent illness, nutrition or protein loss through the kidneys rather than liver disease.
When results need follow-up
NHS pharmacy guidance suggests that results less than twice the upper limit are usually repeated, with further assessment if they stay abnormal, and that results more than two to three times the upper limit need further investigation. Very high ALT or AST levels suggest an acute problem. If your results need medical attention you will be advised to see your GP, and with your consent Juvenology can write to them.
Yellowing of the skin or eyes, dark urine, pale stools or abdominal pain need prompt medical assessment through your GP or NHS 111, whatever an earlier blood test showed.
Liver disease often causes no symptoms until it is advanced. NHS pharmacy guidance also points out that liver blood tests can be normal in advanced disease and abnormal without liver disease, which is why they are interpreted alongside risk factors. Common reasons people choose this panel include:
- a previous result that was slightly abnormal and needs a follow-up figure
- regular alcohol intake, and wanting a baseline before discussing it with a clinician
- excess weight, type 2 diabetes or raised cholesterol, which are linked with fatty liver disease
- taking supplements, herbal products or medicines and wanting a record to share with the prescriber
This panel suits adults who want current liver blood test results to discuss with their GP, particularly with risk factors such as regular alcohol intake, excess weight or type 2 diabetes, or a previous abnormal result.
May not be the right choice
- Possible overdose: if you have taken too much paracetamol or another medicine, go to A&E or call 999 straight away. Do not wait for a blood test.
- New jaundice or severe abdominal pain: seek urgent medical advice instead.
- Medicine monitoring: if a prescriber monitors your liver tests for a specific medicine, continue with that schedule.
- Pregnancy: ALP rises normally in pregnancy and liver problems in pregnancy need assessment by your maternity team.
Established clinical use: liver blood tests are used to detect and monitor liver disease and to check the effects of some medicines. British guidance recommends that, where fatty liver disease is found, liver scarring (fibrosis) is assessed using a score such as FIB-4, which needs age, AST, ALT and a platelet count.
Population associations: fatty liver disease is closely linked with excess weight, insulin resistance and type 2 diabetes, so liver tests are often considered alongside cholesterol and blood sugar. A link at population level does not tell you your own risk.
Emerging research: researchers continue to study how liver enzymes relate to wider metabolic health. These ideas are not established for predicting an individual's future health.
What this test cannot tell you: it cannot measure liver fat, stage fibrosis, screen for liver cancer, predict lifespan or give a "biological age".
- Fasting: not usually needed.
- Exercise: if possible, avoid unaccustomed hard training, especially heavy weightlifting, in the week before, as it can raise AST and ALT for several days.
- Alcohol: note your usual weekly intake honestly; it is important context for anyone interpreting the results.
- Medicines and supplements: keep taking prescribed medicines. List everything you take, including over-the-counter medicines, herbal remedies and bodybuilding or weight-loss products.
- Fluids and sleep: drink normally and, if you have Gilbert's syndrome, be aware that poor sleep and low fluid intake can raise bilirubin.
- Recent illness: a recent infection can temporarily affect liver enzymes and albumin, so consider waiting until you have recovered.
Choose how your sample is taken when you book. We confirm the collection option, any collection fee and the expected turnaround time before you book.
- Juvenology Clinic, Maidstone (82 King Street, Maidstone ME14 1BH): Available.
- Partner clinic near you, anywhere in the UK: Available on request. We confirm availability for your postcode before you book.
- Postal home finger-prick kit: Ask before ordering. We offer a home kit only where the laboratory confirms this test is suitable for a finger-prick sample.
Sample: Venous blood sample (serum); sample tube type confirmed by the laboratory
Collection notes: No fasting needed. Avoid unaccustomed heavy exercise, especially weightlifting, in the week before if possible, as it can raise AST and ALT. Haemolysis can falsely raise AST, which is relevant to finger-prick samples; a postal kit is offered only if the laboratory confirms suitability.
The price of this test covers laboratory analysis and the laboratory's results report. The report lists each result beside the laboratory's reference range.
Beyond the blood test: optional support, priced separately
- Personalised written interpretation report: £50
- General consultation: £50
- Results consultation (results discussion and follow-up advice): £100
- Personalised programme: from £150, after we assess whether a programme suits you
Consultations are with Marina, an NMC-registered nurse. She explains what your results show and how they relate to lifestyle. No prescription service is offered with these tests.
If a result suggests you need medical follow-up, we will recommend that you see your GP and, with your consent, can provide a letter to take with you. A blood test cannot rule out every condition. If you have symptoms, speak to your GP or NHS 111, and call 999 in an emergency.
Is this a complete check of my liver?
No. It shows patterns that suggest liver cell injury or reduced bile flow and gives some information on protein production. It does not include clotting tests, a platelet count, viral hepatitis tests or a scan, and normal results do not exclude every liver condition.
My ALT was raised after a heavy week at the gym. Is that possible?
Yes. Research has shown that intensive weightlifting can raise ALT and AST in healthy people for at least a week. A repeat test after a period of lighter training is often the next step.
Only my bilirubin is high. What could that mean?
An isolated, mildly raised bilirubin with otherwise normal results is often due to Gilbert's syndrome, which is common and harmless. Your GP can confirm this, and may check for causes such as red cell breakdown.
Can this test show whether I have a fatty liver?
Not on its own. Fatty liver can be present with normal liver blood tests. Diagnosis usually involves imaging, and assessing scarring needs additional information, including a platelet count.
Why is globulin listed if it is calculated?
Globulin is total protein minus albumin. It is reported because an unusually high or low value can prompt further tests of the immune system.
Is interpretation included in the price?
The price covers laboratory analysis and the laboratory's report with reference ranges. You can add an optional personalised written interpretation report (£50) or a results discussion consultation (£100).
- Newsome PN, Cramb R, Davison SM, et al. Guidelines on the management of abnormal liver blood tests. Gut, 2018;67(1):6–19. https://doi.org/10.1136/gutjnl-2017-314924
- Assessing liver function and interpreting liver blood tests. NHS Specialist Pharmacy Service, 2024. https://sps.nhs.uk/articles/assessing-liver-function-and-interpreting-liver-blood-tests/
- Kwo PY, Cohen SM, Lim JK. ACG Clinical Guideline: Evaluation of Abnormal Liver Chemistries. American Journal of Gastroenterology, 2017;112(1):18–35. https://doi.org/10.1038/ajg.2016.517
- Pettersson J, Hindorf U, Persson P, et al. Muscular exercise can cause highly pathological liver function tests in healthy men. British Journal of Clinical Pharmacology, 2008;65(2):253–259. https://doi.org/10.1111/j.1365-2125.2007.03001.x
- Gilbert's syndrome. NHS. https://www.nhs.uk/conditions/gilberts-syndrome/
