[Oligospermia improved by switching an anticonvulsant from phenytoin to valproate].

We report a case of 30-year-old man with generalized seizure, who had received phenytoin (PHT) for more than 6 years, but developed decrease in sperm count and motility. After PHT had been discontinued and valproate (VPA) had been administered for 3 months, his sperm activity became normalized. The decrease in sperm motility was the most important cause of his infertility. Sperm motility has been reported to be inversely correlated with the ratio of the concentrations of antiepileptic drugs in the plasma and semen. In our case, the ratio was 0.21 for PHT and 0.08 for VPA. We wish to emphasize the importance of measuring the concentration of antiepileptic drugs in the semen of infertile young males if they are on anticonvulsants.