ESPE Abstracts

Introduction: There is a complex and multifaceted relationship between antiepileptic drugs (AEDs) and the neuroendocrine system. Thyroid hormone (TH) sensitivity reflects thyroid homeostasis more comprehensively than serum hormone levels. It is clear whether TH sensitivity is associated with the use of AEDs. In this study, the evaluation of thyroid hormone sensitivity is aimed in euthyroid cases treated with antiepileptic drug therapy. In this study, the evaluation of thyroid hormone sensitivity will be aimed in euthyroid cases treated with antiepileptic drug therapy by assessing peripheral and central indices.

Materials and Methods: A total of 207 euthyroid pediatric patients using AEDs and followed up for thyroid functions were included. Patients with cardiac, renal, metabolic, muscular system diseases, obesity, diabetes, Hashimoto's thyroiditis, congenital hypothyroidism, and those using glucocorticoids or antihypertensive drugs were excluded. Patients were divided into three groups: those using traditional AEDs, new-generation AEDs, and a combination of traditional and new-generation AEDs. Parameters representing TH sensitivity were evaluated; thyroid feedback quantile-based index (TFQI), parametric thyroid feedback quantile-based index (PTFQI), thyroid-stimulating hormone index (TSHI), and thyrotropin thyroxine resistance index (TT4RI) were used for central sensitivity, while the ratio of free triiodothyronine to free thyroxine (fT3/fT4) was used for peripheral sensitivity.

Results: Of the 207 patients, 35.2% used traditional AEDs. TSH and T3 concentrations were higher in patients using traditional AEDs compared to other groups. Central sensitivity was decreased in patients using traditional AEDs, while peripheral sensitivity was increased. Plasma valproic acid levels were positively correlated with TSHI, and TT4RI, whereas plasma carbamazepine levels were negatively correlated with TSHI, TT4RI, PTFQI, and TFQI. There was no correlation between plasma levetiracetam levels and sensitivity indices.

Discussion: This study demonstrates differences in TH peripheral sensitivity among children using traditional and new-generation AEDs, being the first study to investigate the relationship between TH sensitivity and levels of valproic acid, carbamazepine, and levetiracetam in children. Previous studies have shown an association between the use of different AEDs and thyroid dysfunction, with traditional AEDs being more likely to cause thyroid abnormalities. Valproic acid and carbamazepine have shown to affect thyroid function in children, particularly leading to biochemical thyroid dysfunction and subclinical hypothyroidism, while no relationship has found between levetiracetam and thyroid hormone changes. Our study also demonstrated that VPA and CBZ treatments affect TH sensitivity in euthyroid patients. Therefore, even if thyroid function appears normal in patients using traditional AEDs, evaluating TH sensitivity may provide a more accurate assessment.