Evaluation of long-term follow-up and methimazole therapy outcomes of pediatric Graves' disease: a single-center experience

Background: The management options for Graves' disease in children are limited and there is controversy regarding optimal treatment. Remission rate with anti-thyroid drug (ATD) treatment in children is said to be lower than in adults. Definitive treatments are effective, but they often result in permanent hypothyroidism. The objective of this study was to investigate the outcome of methimazole treatment, identify significant predictors of a remission and evaluate the adverse effects of methimazole in a pediatric population of GD patients. Methods: Medical records of the patients who had been diagnosed with Graves' disease were screened retrospectively. Diagnostic criteria included elevated free thyroxine (fT4) and total triiodothyronine (T3), suppressed thyroid-stimulating hormone (TSH) and either positive thyroid-stimulating immunoglobulin (TSI) or thyroid receptor antibodies (TRABs) or clinical signs suggestive of Graves' disease, for example, exophthalmos. Remission was defined as maintenance of euthyroidism for more than 12 months after discontinuing methimazole treatment. Results: Of the 48 patients, provisional remission was achieved in 21 patients. Of the 21 patients, 14 experienced a relapse (66.6%). Remission was achieved in seven (24.1%) of 29 patients who received methimazole treatment for more than 2 years. In patients who achieved long-term remission, the male sex ratio and fT4 levels at diagnosis were significantly lower than the relapsed and non-remission groups, whereas the free triiodothyronine (fT3)/fT4 ratio and duration of methimazole treatment were significantly higher than the relapse group. Conclusions: Long-term methimazole treatment in pediatric Graves' disease would be appropriate. High fT4 levels at the time of diagnosis and male sex were associated with a risk of relapse.