What is this test?
GGT is an enzyme found mainly in the liver and bile ducts. It can rise with bile-flow problems, alcohol exposure, fatty liver and several medicines, so it is sensitive but not specific.
Why might it be ordered?
- To help interpret an abnormal alkaline phosphatase or other liver tests.
- To monitor a known liver or bile-duct condition.
What sample is needed?
A blood sample is required. The laboratory chooses the correct tube and handles the sample for this test.
How should you prepare?
Ask the laboratory whether you need to fast or attend at a particular time. Do not stop or change medicines or supplements unless your clinician tells you to.
How should you understand the result?
A raised GGT does not identify a single cause and should not be used alone to label alcohol use. The pattern with other liver tests matters.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.