GGT
Gamma-Glutamyl Transferase
What this test measures
GGT is an enzyme found mainly in your liver. It is particularly sensitive to alcohol use and can help identify bile duct problems. This test is often done alongside other liver tests.
Understanding the numbers
Typical range: Men: 10-71 U/L | Women: 6-42 U/L
GGT is very sensitive to alcohol. Even moderate drinking can raise levels.
- Normal: 0–50 U/L
- Mildly raised: 50–150 U/L
- Moderately raised: 150–300 U/L
- Markedly raised: 300–500 U/L
Key numbers
- 42 U/L — Women — upper limit
- 71 U/L — Men — upper limit
- 300 U/L — Marked rise — investigate urgently
UK reference ranges vary by sex. GGT is sensitive but not specific: it rises with alcohol, many medicines, fatty liver, bile-duct disease and obesity. Its main value is confirming that a raised ALP is from liver rather than bone.
Ranges can vary slightly between laboratories — your report may show slightly different numbers. This page does not read or interpret your result; your GP looks at it alongside your history and other tests.
What a higher-than-normal result can mean
- Often raised by alcohol consumption
- Can indicate liver disease or bile duct problems
- Some medicines can raise GGT
- Fatty liver disease is a common cause
Questions you could ask your GP
- Could my alcohol intake be affecting my GGT?
- Do I need to reduce my drinking, and by how much?
- Should I have a liver ultrasound scan?
- Are any of my medicines affecting my liver?
Example stories
These are made-up examples to show how results are talked about in real appointments. They are not real patients.
Mildly raised GGT — moderate drinking
Jas drank a couple of glasses of wine most evenings. His GGT was 95, other liver tests normal, and his MCV was at the top of normal.
What the GP said: “GGT is very sensitive to alcohol. Even 'social' drinking every night can raise it. Try two or three dry days a week and we'll recheck in 8 weeks.”
What happened next: Jas built in four alcohol-free days and halved the amount on drinking days. At 8 weeks his GGT was 38.
GGT is sometimes called 'the drinker's enzyme'. It's one of the few blood tests that reliably reflects alcohol intake. Small, sustained changes in drinking patterns move the number meaningfully.
Markedly raised — bile duct stone
Pete was jaundiced with right upper tummy pain. GGT 420, ALP 510, bilirubin 85. Ultrasound showed a dilated bile duct with a stone.
What the GP said: “A stone is blocking the bile duct. I'm referring urgently for an ERCP to remove it.”
What happened next: ERCP removed the stone. His liver tests normalised over 4 weeks and he had his gallbladder out two months later.
A marked rise in GGT with raised ALP and bilirubin is a cholestatic pattern — the bile is not flowing properly. Gallstones, strictures and tumours are the main causes and they need imaging.
Raised GGT — anticonvulsant medication
Vani has epilepsy on carbamazepine. Her GGT was 140 U/L; other liver tests were normal and she felt well. She did not drink.
What the GP said: “Several medicines, including carbamazepine, induce liver enzymes and raise GGT without causing damage. Your other liver tests are fine. We don't need to change your treatment.”
Medicines like carbamazepine, phenytoin and rifampicin induce liver enzymes and push GGT up without harming the liver. Not every raised GGT means alcohol or disease — the context matters.
Fatty liver — raised GGT with metabolic picture
Diya's GGT was 85, ALT 50. She didn't drink. BMI 32, HbA1c 46, and ultrasound showed a fatty liver.
What the GP said: “This is non-alcoholic fatty liver disease. Weight loss of even 5-7% would bring these numbers back. It's the same path we talked about for the pre-diabetes.”
What happened next: With structured lifestyle support Diya lost 6 kg and her GGT and HbA1c both improved.
GGT rises in fatty liver too, not only alcohol-related disease. In people who don't drink, a raised GGT with a metabolic picture (weight, sugar, cholesterol) is a useful early-warning marker.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.