Key takeaways
- Liver function tests are a panel of eight markers, including ALT, AST, GGT, alkaline phosphatase, bilirubin, total protein, albumin and globulin, that together show how the liver is working.
- A raised ALT, AST or GGT has many possible causes, from alcohol and certain medicines to fatty liver disease or a viral infection.
- Blood London's liver function test panel costs £72.50 plus the £50 blood draw, with results back within 1 day, and no GP referral is needed to book.
- The blood test alone does not diagnose a liver disease; a doctor reads the pattern across all eight markers alongside your symptoms and history before drawing any conclusion.
- Your laboratory report shows the reference range next to each result, so a single raised marker outside that range is a starting point for further discussion, not a diagnosis.
Liver function tests are a blood panel that checks how well your liver is working, by measuring the enzymes, proteins and bilirubin it produces or processes. A raised ALT or AST usually points to inflammation or stress on liver cells, while a raised alkaline phosphatase with GGT points more towards the bile ducts. The liver function tests panel at Blood London measures all eight markers together.
Book liver function tests at 117a Harley Street: £72.50 plus the £50 blood draw, results in 1 day.
What does the liver function test panel actually check?
The panel checks eight markers in one blood sample: bilirubin, ALT, AST, total protein, alkaline phosphatase, albumin, globulin and GGT. Each reflects a different part of how the liver works, from breaking down old red blood cells (bilirubin) to making key blood proteins (albumin, globulin, total protein) and enzymes that leak into the blood when liver cells or bile ducts are irritated (ALT, AST, alkaline phosphatase and GGT). Doctors usually look at the pattern across the panel rather than any single figure, because different combinations of raised or normal markers point in different directions.
What does a raised ALT or AST mean?
A raised ALT or AST usually means liver cells are inflamed or under stress, and the two are often read together to judge that pattern. ALT is found mostly in the liver, so it is a fairly specific marker of liver cell damage. AST is found in the liver and in other tissues, including muscle and the heart, so a raised AST without a raised ALT can sometimes point away from the liver. Common causes of a mild rise include fatty liver disease, alcohol, certain medicines such as some statins or long-term painkillers, viral infection, and even strenuous exercise beforehand, which is why it is worth mentioning recent exercise or alcohol to the phlebotomist.
What does a raised GGT mean?
A raised GGT is sensitive to alcohol intake and to bile duct problems, and it often rises before other liver markers change. GGT can be affected by regular drinking, some medicines, and conditions affecting the bile ducts, so it is frequently read alongside ALT and AST rather than on its own. Blood London's Alcohol Profile includes GGT within a wider set of markers, including PEth and CDT, for anyone who specifically wants a picture of recent drinking (£261.25 plus the £50 blood draw, results in 5 to 7 days).
What does a raised bilirubin mean?
Raised bilirubin can come from a liver or bile duct problem, or from red blood cells breaking down faster than usual, and high levels cause jaundice, a yellowing of the skin or eyes. Bilirubin is a pigment produced when red blood cells break down and is normally processed by the liver and cleared in bile. A mildly raised bilirubin with otherwise normal liver markers is sometimes down to Gilbert's syndrome, a common and harmless variation in how the liver handles bilirubin, though this needs a doctor's assessment rather than self-diagnosis. If you notice yellowing of the skin or eyes, dark urine or pale stools, see a doctor the same day; go to A&E or call NHS 111 if you also feel very unwell, are vomiting repeatedly, or become confused.
| Marker | Where it comes from | Common reasons it is raised |
|---|---|---|
| ALT | Mostly found in liver cells | Fatty liver disease, alcohol, some medicines, viral infection |
| AST | Liver and other tissues, including muscle | Similar to ALT, plus recent strenuous exercise |
| GGT | Liver and bile ducts | Alcohol, some medicines, bile duct problems |
| Alkaline phosphatase | Liver, bile ducts and bone | Bile flow problems, bone conditions; normally higher in teenagers and in pregnancy |
| Bilirubin | Made when red blood cells break down | Liver or bile duct problems; Gilbert's syndrome |
| Albumin | Made by the liver | Reduced liver function or poor nutrition when low |
What does low albumin mean?
Low albumin can reflect reduced liver function, poor nutrition, or a chronic illness elsewhere in the body, since albumin is a protein made by the liver that helps hold fluid in your blood vessels. Total protein and globulin are usually read alongside albumin to give a broader picture. As with the other markers, a low albumin result on its own is a prompt for further assessment rather than a diagnosis, and it is often reviewed alongside full blood count results if fatigue or unexplained weight change is also part of the picture.
Can alcohol or medicines affect my results without liver disease?
Yes, alcohol in the day or two before the test can affect some results even without underlying liver disease, and certain medicines, recent illness or strenuous exercise can also temporarily shift the markers. This is why it is worth mentioning your recent alcohol intake, any new medicines and recent exercise to the phlebotomist when you have the test done, so it can be taken into account when the results are reviewed.
How liver function testing works at Blood London
The liver function test panel costs £72.50 plus the £50 blood draw, which is charged once per visit even if you book other tests at the same time. No fasting is required, though it is worth mentioning recent alcohol intake or any new medicines to the phlebotomist beforehand. Results are usually back within 1 day and sent to you by email. You can walk in or book online at 117a Harley Street, seven days a week, with no GP referral needed, alongside other private blood tests in London. If a viral cause needs ruling out, the Acute Viral Hepatitis Screen checks for hepatitis A, B and C (£175 plus the £50 blood draw, results in 1 day). You can add a doctor review of your report to your test for £75. If any of your results sit outside the laboratory's reference range, a GP appointment at Medical Express Clinic (£150) can look at what has caused it and whether further tests are needed.
Book liver function tests at 117a Harley Street: £72.50 plus the £50 blood draw (£122.50 total), results in 1 day. Start your booking.
Frequently asked questions
Can liver function tests diagnose a liver disease on their own?
No. The blood test flags a pattern that a doctor then interprets alongside your symptoms, history and sometimes further tests such as a scan.
Do I need to fast before liver function tests?
No fasting is required for this panel, though follow any specific instruction from your doctor if you have been given one.
How quickly will I get my liver function test results?
Results are usually back within 1 day and are sent to you by email.
Can exercise affect ALT or AST results?
Yes, strenuous exercise shortly before the blood draw can temporarily raise AST in particular, which is one reason a single raised result is usually repeated rather than acted on straight away.
Is a raised GGT always about alcohol?
Not always. GGT is sensitive to alcohol but can also rise with certain medicines and with bile duct problems, so it is read alongside the other markers rather than in isolation.
What should I do if one of my liver markers is outside range?
Have a doctor look at it: you can add a doctor review to your test for £75, or book a doctor's appointment to discuss the result, your symptoms and history. A single marker just outside the laboratory's reference range is common and often has a straightforward explanation, but it should still be reviewed.
References
- NHS: Non-alcoholic fatty liver disease (NAFLD)
- NHS: Gilbert's syndrome
- British Society of Gastroenterology: Guidelines on the management of abnormal liver blood tests
- Lab Tests Online UK: Liver function tests
- British Liver Trust