THYROID FUNCTION IN EPILEPTIC CHILDREN TREATED WITH SODIUM-VALPROATE MONOTHERAPY: A PROSPECTIVE LONG-TERM STUDY

Abstract

INTRODUCTION: Sodium valproate (VPA) is widely used for the treatment of partial and generalized epilepsy in childhood and adolescence. The results of studies that have evaluated the effect of VPA monotherapy on thyroid function in children are controversial. OBJECTIVE: The aim of this study was to investigate, prospectively, whether treatment with VPA has an effect on serum thyroid hormone concentrations in epileptic children. METHODS: Serum levels of triiodothyronine, thyroxine, free thyroxine, and thyrotropin were determined in 30 epileptic children (aged 2 to 14 years [mean ± SD: 9.10 ± 3.74 years]) before and after 6, 12, and 24 months of VPA monotherapy. RESULTS: Serum levels of thyroxine and free thyroxine were significantly decreased after 6 (P = .000 and .000, respectively), 12 (P = .000 and .015, respectively), and 24 (P = .000 and .003, respectively) months of treatment with VPA, whereas serum levels of triiodothyronine were significantly decreased only after 24 months of treatment (P = .043). Serum levels of thyrotropin were significantly increased after 6 (P = .000), 12 (P = .000), and 24 (P = .000) months of treatment with VPA. Thirteen children (43.3%) had thyrotropin values higher than the normal-range maximum after 6, 12, and 24 months of VPA monotherapy. Serum VPA concentrations remained within the therapeutic range during the period of study. CONCLUSIONS: Our results showed that VPA monotherapy in childhood may cause early and persistent alterations in thyroid function, which suggests a need for early and careful monitoring of serum thyroid hormone concentrations in epileptic children who receive VPA.