GGT and phenytoin

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Phenytoin, phenobarbitol and other aromatic drugs typically cause GGT elevations of about twice normal. A mildly elevated GGT level is a typical finding in patients taking anticonvulsants and by itself does not necessarily indicate liver disease (1).

Like the GGT value, the alkaline phosphatase level can become mildly elevated in patients who are taking phenytoin (1).


  • 1) Johnston DE. Special Considerations in Interpreting Liver Function Tests. AFP 1999.

Last reviewed 01/2018