A comparative study of thyroid status of patients on phenytoin, carbamazepine and valproate monotherapy

Abstract

Background: Anti-epileptic drugs are well tolerated, many effects on endocrine function have been reported, especially, the effect of long-term administration of anticonvulsant drugs on blood thyroid hormone levels. Methods: An analytical, cross sectional, non-randomized study conducted in Neurology Department over a period of twelve months from November 2012 to October 2013 where in 90 patients was enrolled in the study. Results: Of the 90 patients 56 were male and 34 were females. Baseline evaluation of the thyroid status of all patients were noted and showed all the 90 patients were clinically and Para clinically euthyroid. Patients on Phenytoin showed serum TSH value (Mean ± SD) to be statistically higher than the baseline and the normal reference value, whereas no significant difference was noted in the serum free T3 and T4 values. When patients on carbamazepine were evaluated, statistically significant difference was noted in the serum T3 and T4 level and was found to be lower than the reference value. No significant difference was seen in the serum TSH level. Patients receiving valproate showed no significant difference in the serum T3, T4 and TSH before and 6 month after prescription. All the patients were clinically euthyroid and showed no sign and symptoms of hypothyroidism. Conclusions: Valproate monotherapy does not alter serum levels of thyroid hormones. On the contrary, alterations of thyroid hormone function were seen in patients treated with carbamazepine and phenytoin. However, all the patients were euthyroid and were not associated with clinical or even subclinical hypothyroidism.