Liver Function Test Results: Meaning and NHS Lab Ranges

A liver function test is a group of blood tests, usually ALT, ALP, bilirubin and albumin, that shows how the liver is working and whether it is inflamed or its bile ducts are blocked.^{2, 14, 23} There is no single UK normal range for it: across 12 NHS laboratories the upper limit for ALT in men runs from 35 to 60 U/L. A result outside the printed range is read by a GP alongside symptoms, medicines, alcohol intake and other tests^{1, 11}.

This is general information, not advice on your own result¹. Our profiles that include liver tests are listed under blood testing at our Mayfair clinic.

What a liver function test measures

A liver function test is a group of tests rather than a single one, and which markers it includes depends on the laboratory. Severn Pathology in Bristol reports albumin, ALP, ALT and bilirubin, with total protein on request and AST by arrangement¹⁴. North Midlands adds GGT automatically when ALP is high, and AST has to be requested separately²³. The sample is blood from a vein in the arm². Our guide to what a full blood test checks shows where liver tests sit among other common blood tests.

The markers:

• ALT (alanine aminotransferase): an enzyme found mainly in the liver, called "the best test for detecting hepatitis"².
• AST (aspartate aminotransferase): an enzyme found in the liver and also in the heart and other muscles².
• ALP (alkaline phosphatase): an enzyme related to the bile ducts that is also found in bone⁵.
• GGT (gamma-glutamyl transferase): an enzyme that rises in most diseases that damage the liver or bile ducts, and helps show whether a raised ALP comes from the liver or from bone⁶.
• Bilirubin: a yellow pigment from the breakdown of old red blood cells, which the liver processes so that it can leave the body in bile⁷.
• Albumin: the main protein the liver makes².

What NHS laboratories print as the normal range

Normal ranges for liver tests differ between NHS laboratories: across 12 of them the upper limit for ALT runs from 35 to 60 U/L in men and from 33 to 55 U/L in women. We opened each laboratory's own test pages in October 2026. Fourteen services print at least one liver range, in seven English regions, Scotland and Northern Ireland; we found no Welsh laboratory page. Figures are for adults: enzymes in U/L (some laboratories write IU/L), bilirubin in µmol/L and albumin in g/L.

Where a page names a source, it is the analyser maker's kit insert (Roche at Sussex and Belfast, Abbott at Birmingham) or, for ALP, the Pathology Harmony recommendations^{19, 26, 18, 23, 24}. The range on your own report belongs to the laboratory that ran your sample.

ALT, AST and GGT, as printed (men first, then women, where a laboratory splits them):

• Bristol (Severn Pathology): ALT 10 to 60, 10 to 40; AST under 50, under 35; GGT under 55, under 38¹⁴
• Oxford: ALT 10 to 35 for both; AST 15 to 34 for both; GGT 0 to 38, 0 to 55 as printed¹⁵
• Gloucestershire: ALT under 50, under 35; AST under 50, under 35; GGT under 61, under 36¹⁶
• Newcastle: ALT 0 to 50, 0 to 35; AST 0 to 50, 0 to 35; GGT 0 to 70, 0 to 45¹⁷
• Birmingham: ALT 0 to 55 for both; AST 11 to 34 for both; GGT under 55, under 38¹⁸
• Sussex: ALT up to 41, up to 33; AST 0 to 40, 0 to 32; GGT 10 to 71, 6 to 42¹⁹
• North West London: ALT 0 to 45, 0 to 34; AST up to 40 for both; GGT under 55, under 40²⁰
• York and Scarborough: ALT 0 to 45, 0 to 34; AST 0 to 35, 0 to 31; no GGT page found²¹
• South Tees: ALT 1 to 40 for both; AST 1 to 40 for both; GGT 1 to 78, 1 to 54²²
• North Midlands: ALT 0 to 49, 0 to 34; AST 0 to 40 for both; GGT 0 to 35 for both²³
• Eastern Pathology Alliance: AST 11 to 34 for both²⁴
• Edinburgh and Lothians: ALT 10 to 50 for both; AST 10 to 45 for both; GGT 10 to 55, 5 to 35²⁵
• Belfast: ALT under 41, under 33; AST under 40, under 32; GGT 10 to 71, 6 to 42²⁶

The three markers that agree more closely:

• ALP: 30 to 130 at 11 of 14 services (all but Oxford, Edinburgh and Sussex). Oxford prints 30 to 120, Edinburgh 40 to 125, and Sussex 40 to 129 for men and 35 to 104 for women^{15, 25, 19, 27}.
• Bilirubin: the upper limit is 21 µmol/L at 9 of the 10 services with a bilirubin page in the sources. Black Country prints 5 to 26²⁷.
• Albumin: 35 to 50 g/L at 8 of 12 services. Oxford prints 32 to 50, Sussex 35 to 52, Edinburgh 36 to 47 and South Tees 30 to 45^{15, 19, 25, 22}. Gloucestershire notes that its method gives lower albumin results than the one some other laboratories use¹⁶.

Across the services with a range, the upper limits run:

• ALT: men 35 to 60, women 33 to 55 (12 services)
• AST: men 34 to 50, women 31 to 45 (13 services)
• GGT: men 35 to 78, women 35 to 55 (11 services; Oxford's split by sex runs the opposite way to the others)

The same number can therefore be flagged at one laboratory and not at another. As arithmetic about ranges, not a comment on any person's result: an ALT of 46 U/L in a man is above the printed upper limit at 6 of the 12 services and inside it at the other 6.

What a raised or low result can mean

A result outside the range shows that something may be affecting the liver or bile ducts, but not what, and abnormal results can also come from conditions that do not involve the liver.² What the named sources list for each marker:

• ALT: more than 10 times the upper limit is usually acute hepatitis, often viral; chronic hepatitis is often under 4 times. A moderate rise can come with high alcohol intake, diabetes or raised triglycerides (all of which can cause fatty liver), muscle injections, strenuous exercise or some medicines³.
• AST: also rises with heart, kidney or muscle damage, red blood cell breakdown, exercise and muscle injections. Moderate rises are seen in chronic hepatitis, alcohol-related liver disease, bile duct blockage and fatty liver disease⁴.
• ALP: usually a liver or bone disorder, but also higher in growing children, in pregnancy and slightly after a meal in some people; a low ALP is uncommon⁵.
• GGT: rises in most diseases that damage the liver or bile ducts, with drinking alcohol, smoking and many prescription and non-prescription medicines. Alcohol in the 24 hours before the test can raise it temporarily⁶.
• Bilirubin: usually liver disease or a blockage of bile flow such as gallstones, but also faster breakdown of red blood cells². Newcastle describes Gilbert's syndrome as common and benign, typically causing only a mild rise¹⁷.
• Albumin: low in some liver disease, and also with kidney disease, severe inflammation or infection, malabsorption and malnutrition; a high result is less common and can reflect dehydration⁸.

A flagged panel is often not liver disease. In the BALLETS study (BMJ Open, 2013) of 1,290 people with an abnormal panel and no known liver disease, recruited in 2005 to 2008 at 11 GP practices in Birmingham and Lambeth, fewer than 5% were found to have a specific liver disease after further tests¹³. That describes one UK primary-care group, not any one person's result.

What usually happens after a flagged result

After a flagged result the GP reviews it with your symptoms, medicines, alcohol intake and other tests, and may repeat the blood test, arrange further tests or request a scan. The NHS says the GP, nurse or specialist should explain your results and what happens next¹. By marker:

• A high GGT with normal liver enzymes: the doctor may wait and repeat it⁶.
• A high ALP: the doctor first checks whether it is expected (a child, pregnancy, a recent meal), then looks at other liver and bone tests⁵.
• A high AST: other blood tests, possibly an ultrasound or CT scan, and sometimes referral to a liver specialist⁴.
• Possible fatty liver: the GP asks about symptoms, weight and alcohol, and may arrange more blood tests and sometimes an ultrasound¹¹.
• Yellow skin or eyes: the NHS says to ask for an urgent GP appointment or get help from NHS 111¹².

Alcohol is one of the causes the sources list for raised ALT, AST and GGT, and the NHS names it as one of the three main causes of liver disease, with obesity and undiagnosed hepatitis infection⁹. The NHS says you do not have to drink an excessive amount to risk damaging your health, and that regularly drinking just over the recommended levels can be harmful⁹. It advises seeing a GP or an alcohol addiction support service if you have symptoms of liver disease or are worried about your drinking, and warns that stopping suddenly after regularly drinking too much can be very dangerous, so medical help comes first¹⁰.

Which of our blood test profiles include liver function tests

Liver function tests (LFTs) are listed in three of our profiles, the Essential Blood Profile, the Well Woman Profile and the Well Man Profile, and results come back within 24 to 48 hours. The Essential Blood Profile lists FBC, LFTs, kidney, bone, lipids, iron studies and glucose; the Well Woman and Well Man profiles add ESR, TSH, FT4, ferritin, CRP, B12, folate and vitamin D, with PSA for men. Testing begins with a complimentary nurse consultation, or you can choose a doctor consultation to decide what to test. Our price list names the group as "LFTs" rather than listing each marker, so the consultation is the place to ask which are included.

Common questions

Does a normal liver function test rule out liver disease?

No: Lab Tests Online UK says normal results can be found in people with serious liver disease.² The NHS says most types of liver disease cause no symptoms in the early stages, and advises seeing a GP if you think you might have it⁹.

Do I need to fast for a liver function test?

It depends on the laboratory and the tests requested, so follow what the person arranging the test tells you. The NHS says the GP, nurse or specialist should tell you if you need to prepare in any way¹. Lab Tests Online UK's liver blood tests page says "None" for test preparation yet describes the sample as taken "sometimes after fasting"², and Newcastle's laboratory says patients should be fasted for ALP¹⁷.

Sources

1. Blood tests, NHS, reviewed 2023
2. Liver blood tests, Lab Tests Online UK, viewed October 2026
3. Alanine aminotransferase (ALT) test, Lab Tests Online UK, viewed October 2026
4. Aspartate aminotransferase (AST) test, Lab Tests Online UK, viewed October 2026
5. Alkaline phosphatase (ALP) test, Lab Tests Online UK, viewed October 2026
6. Gamma-glutamyl transferase (GGT) test, Lab Tests Online UK, viewed October 2026
7. Bilirubin, Lab Tests Online UK, viewed October 2026
8. Albumin, Lab Tests Online UK, viewed October 2026
9. Liver disease, NHS, reviewed 2023
10. Alcohol-related liver disease (ARLD), NHS, reviewed 2026
11. Non-alcoholic fatty liver disease (NAFLD), NHS, reviewed 2025
12. Jaundice, NHS, reviewed 2024
13. BALLETS study of abnormal liver function tests, BMJ Open, 2013
14. Severn Pathology, North Bristol NHS Trust, test information, viewed October 2026: ALT, AST, ALP, bilirubin, gamma GT and LFT
15. Oxford University Hospitals NHS Foundation Trust, clinical biochemistry test catalogue, 2024 to 2026: ALT, AST, ALP, GGT, bilirubin and albumin
16. Gloucestershire Hospitals NHS Foundation Trust, pathology tests, 2015 to 2026: ALT, AST, ALP, GGT and albumin
17. Newcastle Hospitals laboratories, test directory, 2024 to 2026: ALT, AST, ALP, GGT, bilirubin and albumin
18. University Hospitals Birmingham NHS Foundation Trust, pathology tests database, 2026: ALT, AST, ALP, GGT and albumin
19. University Hospitals Sussex NHS Foundation Trust Pathology, viewed October 2026: ALT, AST, GGT, ALP, bilirubin and albumin
20. North West London Pathology, 2025: ALT, AST, ALP, GGT, bilirubin and albumin
21. York and Scarborough Teaching Hospitals NHS Foundation Trust, laboratory medicine test directory, viewed October 2026: ALT, AST, ALP and albumin
22. South Tees Hospitals NHS Foundation Trust, pathology tests, 2022 to 2026: ALT, AST, GGT, ALP, bilirubin and albumin
23. University Hospitals of North Midlands NHS Trust, pathology tests, 2018 to 2025: ALT, AST, ALP, GGT, total bilirubin, albumin and liver function tests
24. Eastern Pathology Alliance, viewed October 2026: AST, ALP and albumin
25. Edinburgh and Lothians Laboratory Medicine, NHS Lothian, viewed October 2026: ALT, AST, GGT, ALP, bilirubin and albumin
26. Clinical biochemistry user manual, Belfast Health and Social Care Trust, 2026
27. Black Country Pathology Services, viewed October 2026: ALP and bilirubin