Gamma glutamyl transpeptidase (gamma GT)

Gamma-glutamyl transpeptidase is an enzyme which is found in hepatocytes and biliary epithelial cells. GGT may be high in liver disease. In particular it is a feature of biliary outflow obstruction rather than hepatocellular damage.

• GGT (in men) = 11 - 50 i.u./l
• GGT (in women) = 7 - 32 i.u./l

Note reference ranges may vary between laboratories.

GGT serum measurement provides a very sensitive indicator of the presence or absence of hepatobiliary disease. However the usefulness of measurement of serum GGT is limited by its lack of specificity. Raised GGT levels have been reported in a variety of clinical conditions including (1):

• pancreatic disease
• myocardial infarction
• chronic obstructive pulmonary disease
• renal failure
• diabetes
• obesity
• alcoholism

Drugs such as phenytoin and barbiturates may cause high GGT levels (1).

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The linked page GGT in hepatobiliary disease details hepatobiliary causes of a raised GGT.

Reference:

1. Royal Pharmaceutical Society. Liver function tests: indication and interpretation. Feb 2022 [internet publication].