Gamma-GT (GGT)
Liver enzyme for bile duct disorders, alcohol use, and oxidative stress
Also known as
Definition
Gamma-glutamyltransferase (GGT, also γ-GT) is an enzyme involved in amino acid transport and glutathione metabolism, found in the liver, bile ducts, kidneys, and pancreas. GGT is the most sensitive indicator of liver damage from alcohol, medications, or bile duct disease. Elevated GGT is also a marker of oxidative stress and metabolic syndrome.
| Parameter | Value |
|---|---|
| Unit | U/l |
| Reference Range | Women: < 40 U/l | Men: < 60 U/l (lab-dependent) |
Agree on your personal target range with your doctor.
↓ What a low value means
Low GGT is clinically unremarkable. No pathological condition is known at low values.
↑ What a high value means
The most common causes of elevated GGT are: alcohol consumption (even small amounts over weeks raise GGT), fatty liver (NAFLD/MAFLD), medications (antiepileptics, statins, methotrexate), bile duct obstruction, pancreatic disease. GGT rises earlier than GOT/GPT with chronic alcohol abuse.
✓ What can influence this value
GGT is influenced by alcohol consumption (can raise the value within weeks; after several weeks of abstinence it usually falls again), fatty liver diseases (NAFLD/MAFLD) and body weight, medications such as antiepileptics or statins, and diseases of the bile ducts. In observational studies, regular coffee consumption was associated with lower GGT values. The assessment is made by the treating doctor.
When to test
Routinely in the liver panel with GOT, GPT, ALP, and bilirubin. For alcohol history, liver disease, gallbladder complaints, medication monitoring. GGT as a follow-up parameter for treatment response (alcohol abstinence, weight loss).
Frequently asked questions
Is GGT really a good alcohol marker during abstinence? +
GGT is the most sensitive clinical marker for chronic alcohol abuse — more sensitive than GOT or GPT. The half-life of GGT after alcohol withdrawal is approximately 14–26 days. Full normalization after complete abstinence takes 4–6 weeks. CDT (carbohydrate-deficient transferrin) complements GGT for follow-up monitoring.
Is coffee consumption linked to GGT values? +
In epidemiological and prospective cohort studies, regular coffee consumption was associated with lower GGT values. Such observational studies do not show whether coffee causes the value to fall. Proposed mechanisms include polyphenol-mediated hepatoprotection, inhibition of liver fibrosis, and antioxidant effects of chlorogenic acids.
Is a liver biopsy always done when GGT is elevated? +
No. Mildly elevated GGT without symptoms is usually first assessed through history (alcohol, medications), ultrasound, and follow-up observation. Which further tests follow, for example with a marked or persistent rise or together with other abnormal liver values, is decided by your doctor.
Why is GGT lower in women than men? +
Estrogen suppresses GGT expression in the liver. Postmenopausal women have higher GGT values than premenopausal women. Sex-specific reference ranges matter: a value of 45 U/l is elevated in a premenopausal woman but still normal in a man.
Gamma-GT (GGT)
Sources
Last updated: May 28, 2026
This information is for orientation only and does not replace medical advice. Reference ranges can vary by laboratory, method and country.