To assess the prevalence of hyponatremia in epileptic children receiving carbamazepine or oxcarbazpine, we investigate serum sodium changes according to age, serum carbamazepine level, and daily oxcarbazepine dosage, and the prevalence of symptoms of hyponatremia.

We reviewed the clinical data of the 197 children receiving carbamazepine and/or oxcarbazepine with or without antiepileptic therapy. And these were classified into the carbamazepine treated patients (group I), oxcarbazepine treated patients (group II), and carbamzepine or oxcarbazepine with other antiepileptics treated patients (group III). Potentially predictive values for development of hyponatremia were examined in each group: age, plasma level of carbamazepine and daily dosage of oxcarbazepine. We assessed the symptoms of hyponatremia.

The overall prevalence of hyponatremia was 20.8% (group I, II and III: 17.9%, 22.6%, and 21.8%, respectively), and the prevalence in groups II and III compared with controls ( P <0.03) was significantly lower. The changes of serum sodium levels relation to age were not significantly different. The changes of serum sodium levels by increasing of serum levels of carbamazepine and dosage of oxcarbazepine were statistically significant ( P <0.01). Among the 41 patients who had biochemical hyponatremia, the prevalence of hyponatremic symptoms was 17.1%.

Hyponatremia may occur relatively more frequently with oxcarbazepine or combined other antiepileptics than carbamzepine therapy only. Age of children receiving carbamazepine or oxcarbazepine was no predictive value for occurrence of hyponatremia. The patients whose serum level were less than 125 mEq/L showed more severe clinical symptoms than any other study groups.