What it measures
Gamma-glutamyl transferase (GGT) is an enzyme found mainly in the liver and bile ducts. It rises with bile duct problems, regular alcohol intake and some medicines, and is often read alongside ALP.
Why people test it
- Part of many liver function tests, used to help tell whether a raised ALP comes from the liver or from bone.
- Measured when regular drinking may be affecting the liver, as alcohol raises GGT.
- Checked when fatty liver or bile duct problems are suspected.
- Not raised by muscle damage, so it helps separate a training effect on ALT and AST from a liver cause.
Typical range
Ranges vary between labs with the method used, age and sex, and your report shows the lab's own range. One NHS trust's lab uses 6 to 40 U/L for women and 12 to 68 U/L for men. Source: Leeds Teaching Hospitals NHS Trust: Blood Sciences Reference Range Database v3.20.
Finger-prick or vein?
A finger-prick sample is usually fine for GGT.