A Prospective Cohort Study on the Effect of Antiseizure Medications on Thyroid Function in Children Aged 6 Months to 12 Years with Epilepsy.

Objectives: This study aimed to explore the effect of antiseizure medications (ASM) on thyroid function in children with epilepsy.

Methods: A prospective study involving children between 6 months and 12 years of age with new-onset seizures who took ASM within 2 months was conducted in the Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, India, between August 2019 to March 2022. Thyroid function tests-free T3, free T4 and thyroid stimulating hormone (TSH)-were done at baseline and after completing 3 months by competitive immunoassay using direct chemiluminescent technology. The primary outcome was the proportion of patients diagnosed with thyroid dysfunction (subclinical or overt hypothyroidism).

Results: In total, 126 patients were enrolled. Median (interquartile range [IQR]) age and follow-up months were 10 years (7-12) and 6 months (4-8), respectively. Most patients (n = 103, 81.7%) had generalised seizures, while the remaining (n = 23, 18.3%) had focal seizures. There was a significant difference noted in median (IQR) TSH (micro-IU/mL) at baseline (2.08 [1.41-3.31]) and follow-up (2.56 [1.65-4.14]; P ≤0.001). Thyroid dysfunction (subclinical hypothyroidism) was noted in 7 patients. Among the 7 children with subclinical hypothyroidism, 6 (4.8%) were on sodium valproate either as monotherapy (n = 3, 2.4%) or polytherapy (n = 3, 2.4%), while the remaining child was on phenytoin. No difference was noted between the monotherapy and polytherapy groups (4% versus 11.5%; P = 0.15).

Conclusion: The incidence of thyroid dysfunction (subclinical hypothyroidism) was 5.6% in children taking ASM with a median follow-up period of 6 months. A longer follow-up period and larger sample size study is warranted in the future.