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

This study aimed to explore the effect of antiseizure medications (ASM) on thyroid function in children with epilepsy. 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). 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]; ≤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%; = 0.15). 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.