Effect of carbamazepine and valproic acid monotherapy on thyroid function tests in epileptic patients

Objectives: This study was conducted to assess the effect of carbamazepine (CBZ) and sodium valproate (VPA), as a monotherapy in epileptic patients, on thyroid function tests as assessed by serum total triiodothyronine (TT3), total thyroxine (TT4) and thyroid stimulating hormone(TSH). Subjects and methods: Sixty three epileptic patients using monotherapy were included in the study. These included 44 patients using CBZ and 19 using VPA. A control group of 47 apparently healthy individuals were also included in the study for comparison. Measurement of TSH, TT3 and TT4 was done using Gamma counter.Results: The results of this study revealed that patients on CBZ showed significantly decreased mean level of TT4 in comparison with the control group (P0.05). In the VPA group, mean TT3, TT4 and TSH values showed insignificant differences from the control group (P>0.05).Conclusion: Unlike VPA, CBZ significantly decreases level of TT4 without affecting TT3 and TSH levels. Keywords: Carbamazepine, sodium valproate, thyroid function tests.