Antithyroid Drug Treatment for Graves' Disease in Children: A Long-Term Retrospective Study at a Single Institution

BACKGROUND: The management of Graves' disease (GD) in children is associated with a dilemma. Although the established initial treatment for GD in children is antithyroid drug (ATD) treatment, the remission rate in children is said to be lower than in adults, and severe propylthiouracil-induced adverse events (AEs) are an issue. Definitive treatments are effective, but they often result in permanent hypothyroidism and the need for lifelong T4 supplementation. OBJECTIVE: The objective of this study was to investigate the outcome of ATD treatment, identify significant predictors of a remission, and evaluate the AEs of ATDs in a large pediatric population of GD patients. METHODS: We retrospectively assessed the reports of 1138 children up to 18 years of age who had been newly diagnosed with GD at our institution between 1982 and 2006. Their median age at diagnosis was 16 years (range: 3-18 years), and there were 995 females and 143 males. All patients were initially treated with an ATD. Remission was defined as maintenance of euthyroidism for more than 12 months after discontinuing ATD treatment and the absence of any relapses during the follow-up period. RESULTS: Of the 1138 patients, 723 continued on ATD treatment, 271 underwent surgery or radioactive iodine therapy, and 144 dropped out. Of the 723 patients who continued on ATD treatment, ATD treatment was subsequently ongoing in 84 and was discontinued in 639 (median duration of treatment: 3.8 years; range: 0.3-24.8 years). Of the 639 patients who discontinued ATD treatment, 334 (46.2%) achieved a remission, 247 (34.2%) experienced a relapse, and 58 (8.0%) dropped out. The cumulative remission rate increased with the duration of ATD treatment up until five years. No significant predictors of a remission were identified. The overall incidences of AEs associated with methimazole and propylthiouracil were 21.4% and 18.8% respectively. There were no fatal AEs in our population. While most AEs (91.6%) occurred within the first three months of ATD treatment, 2.7% developed more than two years after the start of ATD treatment. Seven of the eight late-onset AEs were induced by propylthiouracil. CONCLUSION: Long-term ATD treatment is a useful treatment option for GD in children.