Gamma-glutamyl transferase (GGT) is elevated with most liver diseases and with bile duct damage. Its main clinical use is in the evaluation of patients with isolated elevation in alkaline phosphatase (which can be of hepatic or bone origin). However, there are extrahepatic causes of GGT elevation including pancreatitis, prostate carcinoma, breast carcinoma, lung carcinoma, systemic lupus erythematosus, and congestive heart failure.