[Serum folic acid in anticonvulsant long term therapy (author's transl)]

No significant difference was found in a comparison between the values of unreduced serum folic acid of 48 epileptics treated with hydantoin and 38 controls as measured by a competitive protein-binding assay. The average folic acid value was 7.73 nmol/l in the epileptics, a little higher than the 7.18 nmol/l found in the controls. This result supports the hypothesis that the folate deficiency in epileptics is caused by blocking the conversion of folic acid to 5-methyltetrahydrofolic acid by phenytoin.