Urinary N-acetyl-beta-D-glucosaminidase in epileptic children treated with antiepileptic drugs.

Aim: To investigate the effect of prolonged use of antiepileptic drugs on renal function in children.

Methods: Prospective study of 72 children (aged 3-18 years) with epilepsy, on either monotherapy (n = 44) or combined therapy (n = 28). The length of treatment varied from 1 to 13 years. Drugs used were valproic acid, carbamazepine, ethosuximide, clonazepam, clobazepam, and vigabatrin.

Results: In 65 patients plasma concentrations of the drugs were in the therapeutic range. In the remaining seven, plasma concentrations were slightly high. In 33 patients urinary N-acetyl-beta-D-glucosaminidase (NAG) activity was raised. The incidence of pathological NAG indices was significantly higher in the combined therapy group than in the monotherapy group. There were also significant differences in the NAG indices of patients depending on the duration of therapy.

Conclusions: Results suggest that chronic use of some antiepileptic drugs-in spite of normal blood concentrations-may alter tubular function, and the dysfunction may result in clinical symptoms. Therefore, we recommend screening of tubular function in these patients.