Central Hypothyroidism Associated with Oxcarbazepine in Pediatric Patients: Case Series and Literature Review

Central hypothyroidism, a hypothyroid state resulting from insufficient stimulation by thyrotropin (TSH) of an otherwise normal thyroid gland, is a rare under-recognized side effect of oxcarbazepine. We describe four young patients diagnosed with central hypothyroidism likely due to oxcarbazepine and conducted a literature review for previously published cases. Four patients ranging in age from 11-20 years were treated with oxcarbazepine and were subsequently found to have low free thyroxine (FT4) levels and inappropriately normal thyroid stimulating hormone (TSH) concentrations. All had normal thyroid examinations and normal morning cortisol. The two patients who were still growing had normal growth hormone markers. Magnetic resonance imaging (MRI) of the brain was normal in all. Three of the patients experienced symptoms consistent with hypothyroidism; treatment with levothyroxine led to resolution of symptoms. Three of the patients discontinued oxcarbazepine; subsequently all had normalization of thyroid function. Oxcarbazepine can lead to low FT4 concentrations with normal TSH values. Assessment of TSH and FT4 could be included in the periodic screening of patients taking oxcarbazepine. A limited number of reported cases have suggested that monitoring of thyroid function studies may be indicated in patients taking oxcarbazepine, to monitor for development of CH.