Liver and pancreas · Blood

Gamma-GT

An enzyme from the liver and bile ducts that rises when the liver is under strain, mainly from alcohol, medicines or a bile duct problem.

At a glance

Measured in blood
In 12 test panels
No special preparation

Explanation

Gamma-GT: what is measured?

Gamma-GT (gamma-glutamyltransferase, GGT) is an enzyme found mainly in the cells of the liver and the small bile ducts. It enters the blood when those cells are irritated or damaged. This happens with alcohol use, with many medicines, with fatty liver and when the outflow of bile is blocked. Gamma-GT is often assessed together with alkaline phosphatase: if alkaline phosphatase is raised, a raised gamma-GT indicates that the cause lies in the liver or bile ducts and not in the bone.

What can it detect?

Strain on the liver from alcohol (gamma-GT is the most sensitive routine test for this, but not specific)
Blocked bile outflow (cholestasis), for example due to gallstones or a narrowing of the bile duct
Liver damage from medicines or fatty liver
Distinguishing between liver and bone when alkaline phosphatase is raised

Result

What does the result mean?

Gamma-GT too high

A raised gamma-GT is common and is not a diagnosis on its own. The most common causes are regular alcohol use (even a few glasses in the days before the blood draw), fatty liver with overweight or diabetes, and medicines such as antiepileptics, some antidepressants, antibiotics and statins. After stopping alcohol, it often takes a few weeks to a month before the value is normal again. A strongly raised gamma-GT together with a raised alkaline phosphatase and bilirubin fits obstructed bile outflow; symptoms are then pain in the upper right abdomen, jaundice, itching, dark urine and pale stool. Smoking and a higher weight also give a higher gamma-GT on average.

Gamma-GT too low

A low gamma-GT has no significance. The value is lower on average in women than in men and falls with use of the contraceptive pill.

After an abnormal result

The GP assesses gamma-GT together with ALT, alkaline phosphatase and bilirubin, and asks about alcohol and medicines. With a raised value without symptoms, a repeat measurement usually follows after a few weeks without alcohol; if the value stays raised, testing for fatty liver follows and, if needed, an ultrasound of the liver and bile ducts.

Reliability

How reliable is the test?

Gamma-GT is sensitive but not very specific: it rises with many different causes and says nothing about the severity of liver damage. As a test for excessive alcohol use, gamma-GT has limited value: according to the Dutch GP guideline (NHG) on problematic alcohol use, some people who drink too much have a normal gamma-GT, and a raised value often has another cause. For the question of how much someone drinks, a conversation or questionnaire is more reliable than a blood test; CDT is more specific for alcohol but less sensitive.

What can affect the result?

Alcohol in the week before the blood draw raises the value; even a single evening of heavy drinking can raise gamma-GT for a day.
Many medicines raise gamma-GT without liver damage, including antiepileptics (carbamazepine, phenytoin), some antidepressants and statins.
Overweight, diabetes and smoking give higher values on average; men have higher values than women.
Reference values differ per laboratory.

Who it is for

Who is the test useful for?

Useful for

Useful with a raised alkaline phosphatase to distinguish between liver and bone, when a bile duct problem is suspected, when monitoring liver damage from medicines, and when you want to see for yourself whether alcohol is putting strain on your liver, for example when cutting down or stopping. As proof of alcohol use or, on the contrary, of abstinence (for example for the CBR, the Dutch driver's license authority), gamma-GT alone is not enough; separate requirements apply and CDT is usually measured as well. In healthy adults without risk factors, routine measurement is not needed.

How common is it?

Excessive alcohol use (more than 21 glasses per week for men or 14 for women) occurs in about 5 to 6 in 100 adults in the Netherlands, about twice as often in men as in women. In a large proportion of them, gamma-GT is raised. A raised gamma-GT due to fatty liver or medicines is even more common.

VZinfo (RIVM), alcohol use in adults 2025; the NHG guideline on problematic alcohol use

Drawbacks and risks

A raised gamma-GT is quickly linked to alcohol, while fatty liver and medicines are just as often the cause; this can unfairly label someone.
A normal gamma-GT does not rule out excessive alcohol use.

Get tested

Gamma-GT: test panels

Gamma-GT is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.

Blood draw
Gamma-GT and CDT (alcohol use)
Gamma-GT and CDT; liver function and alcohol intake.
€ 53,00
Blood draw
Gamma-GT
Gamma‑GT; liver and bile ducts.
€ 23,00
Blood draw
Bodybuilder Test
Panel for strength and muscle development; hormones, liver, and muscles.
€ 134,00
Blood draw
General Health Checkup
With this General Health Check-up, you gain detailed insight into your overall health and well-being.
€ 125,00
Fingerstick
Gamma-GT
Gamma-GT; liver and bile ducts.
€ 23,00
Blood draw
InsideTracker
InsideTracker Blood Analysis: analyze 48 biomarkers for complete health optimization and personalized recommendations.
€ 335,00
Blood draw
Testosterone Replacement Therapy (TRT)
Testosterone, LH, FSH, Oestradiol, Prolactin, liver function, and blood values. For men with low testosterone or TRT monitoring.
€ 175,00
Blood draw
Hormone Recovery (After Steroids)
Testosterone, free testosterone, SHBG, LH, FSH, estradiol, TSH, liver function, and lipid profile. For recovery after anabolic steroid use.
€ 325,00
Blood draw
Liver
ALT, AST, Gamma-GT, alkaline phosphatase, and bilirubin. Assesses liver health in cases of alcohol use, medication, or liver complaints.
€ 58,00

How reliable is the test?

Gamma-GT