The Effect of Anticonvulsant Drugs on Serum Thyroid-Stimulating Hormone

Abstract

Objective: Antiepileptic (AED) drugs are an integral component of the management of seizure disorder; however, they have a wide spectrum of adverse effects. It is important to be aware of these side effects as they have a major impact on the quality of life and are sometimes partially reversible after drug discontinuation. Among them, the influence of AED on thyroid function is an important one. However, there is only limited data available. The objective of this study is to evaluate the effect of AED on thyroid-stimulating hormone (TSH).
 Methods: A cross-sectional study of 1-year duration (march 2017 – march 2018) was conducted among 150 epileptic patients receiving phenytoin, carbamazepine, and sodium valproate for more than 6 months in a tertiary care center in central Kerala. Serum levels of TSH of patients on AED were compared with that of 50 healthy age- and sex-matched control groups. Data regarding the same were analyzed using SPSS version 16 with the Chi-square test, ANOVA, and independent t-test.
 Results: A total of 150 epileptic patients with a mean age of 35.54 + 10.72, including 66 males (44%) and 84 females (56%) were enrolled in this study. Fifty adults of mean age 36.5+ 8.4 and male to female ratio 1.10:1 formed the control group. It was found that the mean TSH value of patients on phenytoin (3.97+ 1.47), carbamazepine (3.57+ 1.44), and sodium valproate 3.03 + 1.41 significantly higher than that of the control group (1.91 + 0.72). On comparing the mean serum TSH of the drug group significant difference noted between phenytoin and sodium valproate treated group. Among the 12 patients develop subclinical hypothyroidism 65% taking drugs for more than 5 years.
 Conclusion: There is a positive correlation between the use of anticonvulsants and thyroid dysfunction and the association increases with the duration of therapy. The clinicians should be encouraged for regular monitoring of thyroid function test to impart a better quality of life to the patients.