Clinical Chemistry - Gamma GT

Gamma-glutamyltransferase (GT) in serum originates primarily from the hepatobiliary system. Therefore GT is elevated in all forms of liver disease and has been shown to be more sensitive than alkaline phosphatase in detecting obstructive jaundice, cholangitis and cholecystitis. High levels of GT are also seen in patients with primary or secondary liver cancer. Increased levels are also observed in cases of alcohol abuse and in alcoholic liver cirrhosis. In patients receiving anticonvulsant drugs such as phenytoin and phenobarbital, increased levels of the enzyme in serum may reflect induction of new enzyme activity and the toxic effects of alcohol and other drugs on the microsomal structures in liver cells. GT is the most sensitive enzymatic indicator of hepatobiliary disease, and can be used in combination with other biochemical markers to discriminate between different types of hepatobiliary disease.