Evaluation of renal tubular function in children taking anti-epileptic treatment

Aim:  To assess the effects of anti-epileptic drugs on renal tubular function.

Methods:  Urinary N-acetyl-β-D-glucosaminidase activity was measured in 114 epileptic children (mean age 5.6 ± 1.1 years) who were undergoing monotherapy with valproate (n = 46), carbamazepine (n = 34), lamotrigine (n = 13) and combined therapy with valproate+carbamazepine (n = 21).

Results:  The urinary N-acetyl-β-D-glucosaminidase index of valproate (P < 0.01), carbamazepine (P < 0.05) and polytherapy group (P < 0.01) were significantly elevated when compared with that of the control group. No significant difference in N-acetyl-β-D-glucosaminidase levels was found between the lamotrigine group and the control subjects. We found that the distribution of the N-acetyl-β-D-glucosaminidase values of patients depended significantly on the length of therapy (P < 0.01). The level of urinary excretion of N-acetyl-β-D-glucosaminidase was significantly higher in the patients who were taking long-term treatment (>10 years) with valproate, carbamazepine and combined therapy than those taking therapy shorter than 10 years (P < 0.01). The mean serum concentrations of valproate and carbamazepine were 68.7 ± 17.44 µg/mL and 5.41 ± 1.23 µg/mL, respectively. There was a significant correlation between the serum concentration of valproate and urinary N-acetyl-β-D-glucosaminidase levels (r = 0.44, P < 0.01). There was also a significant correlation between the serum concentration of carbamazepine and N-acetyl-β-D-glucosaminidase excretion (r = 0.52, P < 0.01).

Conclusion:  The present study demonstrated that in patients treated with valproate and carbamazepine, an impairment of tubular function can be present, whereas lamotrigine does not cause any significant change.