Liver health

Gamma-glutamyl transferase (GGT)

Gamma-GT, GGTP

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GGT responds to alcohol and to changes in bile flow.

GGT is an enzyme found mainly in the liver and bile ducts. It's a sensitive marker that can rise with alcohol, some medications, and conditions affecting the liver or the ducts that drain bile.

GGT is sensitive, so it works best with other results.

GGT rises easily, which makes it a useful early signal and a less useful marker on its own. Regular drinking, even at moderate levels, can raise it, and so can certain medications and supplements.

Clinicians often use GGT to explain other results. If alkaline phosphatase (an enzyme found in both liver and bone) is high, a high GGT suggests the liver or bile ducts are the source. A normal GGT points more toward bone.

Questions

What can raise GGT?

Regular alcohol use is a common cause. Fatty liver, some medications and supplements, smoking, and conditions affecting the liver or bile ducts can raise it too.

Does a high GGT tell me what's wrong?

It can show that the liver or bile ducts are under stress, but it can't identify the cause. A clinician reads it with ALT, AST, and your history of alcohol use, medications, and other conditions.

Does alcohol before the test matter?

Your usual drinking pattern has the biggest effect on GGT, so be open about it with your clinician. If your lab gives you instructions about alcohol or fasting before your draw, follow them so results are easier to compare over time.

Sources and references