Gamma-glutamyltransferase

Gamma-glutamyltransferase (GGT) is an enzyme that is found in many organs throughout the body, with the highest concentrations found in the liver. It is involved in the transfer of amino acids across the cellular membrane and in glutathione metabolism, which is crucial for the detoxification of the body.

Function

Gamma-glutamyltransferase catalyzes the transfer of gamma-glutamyl functional groups from molecules such as glutathione to an acceptor that may be an amino acid, a peptide or water (forming glutamate). This enzyme plays a key role in the gamma-glutamyl cycle, a pathway that regenerates glutathione in the body and detoxifies the body from harmful substances.

Clinical significance

Elevated levels of GGT in the blood are most commonly due to liver diseases. In particular, alcohol consumption and fatty liver disease can cause high GGT levels. However, GGT elevation can also indicate disease in the biliary tract and pancreas. GGT is a sensitive but non-specific marker of disease; therefore, it is not useful in identifying the exact cause of disease, but can indicate that further diagnostic testing is needed.

Measurement

GGT levels are commonly measured in blood tests. Normal levels of GGT in the blood are 9–48 U/L in men and 6–29 U/L in women. Levels above these ranges may indicate a medical condition that needs further investigation.

See also

• Liver function tests
• Alcoholic liver disease
• Non-alcoholic fatty liver disease