Value of serum gamma-glutamyltransferase activity in the diagnosis of hepatobiliary disease.

Serum gamma-glutamyltransferase activity (GGT) has been measured in 150 patients with a variety of hepatobiliary disorders. GGT concentration was significantly higher in patients with "cholestatic" liver disease than in those with "hepatic" disorders, although there was considerable overlap. Measurement of GGT alone did not allow differentiation of intrahepatic cholestasis from extrahepatic cholestasis. However, GGT/serum bilirubin ratios were significantly higher in patients with intrahepatic cholestasis when compared with patients with extrahepatic biliary obstruction. Estimation of serum concentration of GGT appears to be a sensitive screening test both for alcohol consumption and for hepatobiliary disease. However, measurement of GGT concentration has only limited value in the differential diagnosis of hepatobiliary disease, although it may help in the differentiation of "hepatitic" and "cholestatic" liver disease.