Activity of gamma-glutamyl transpeptidase in serum of patients receiving anticonvulsant of anticoagulant therapy.

1. Effects of chronic anticoagulant therapy in heart patients and anticonvulsant therapy in epileptics on gamma-glutamyl transpeptidase activity in serum were investigated. 2. The enzyme was elevated in 22% of 18 patients receiving anticoagulants. In these patients prothrombin time was also abnormally high. 3. 84% of 65 epileptics exhibited elevated gamma-glutamyl transpeptidase activity, 67% of which were not associated with elevated alkaline phosphatase or aspartate aminotransferase activities. In these latter cases, involvement of the liver was not apparent. 4. Possible relationships of anticonvulsant mediated enzyme induction or hepatic toxicity to elevated gamma-glutamyl transpeptidase activity in serum in epileptics is discussed.