Comparison of methimazole and propylthiouracil in the management of children and adolescents with Graves’ disease: efficacy and adverse reactions during initial treatment and long-term outcome

OBJECTIVE: The aim of this study was to compare the efficacy and adverse reactions during initial treatment and long-term outcome between children and adolescents with Graves' disease (GD) treated with propylthiouracil (PTU) and those treated with methimazole (MMI). DESIGN, SETTING AND PARTICIPANTS: Retrospective and collaborative study. Children and adolescents with GD were divided into group M (MMI: n=64) and group P (PTU: n=69) and into four subgroups by initial dose: group M1 (<0.75 mg/kg of MMI, n=34), group M2 (> or = 0.75 mg/kg, n=30), group P1 (<7.5 mg/kg of PTU, n=24) and group P2 (> or = 7.5 mg/kg, n=45). MAIN OUTCOME MEASURES: The duration for normalization of serum T4 on initial treatment, the incidence of adverse effects for one year and outcomes at 10 years after were compared. RESULTS: Mean durations for normalization of T4 (+/- SD) were 1.7 +/- 1.0 months in group M and 2.3 +/- 2.4 in group P [not significant (NS)], while the mean duration in group P1 (3.1 +/- 3.3) was significantly longer than those in the other subgroups (M1: 1.9 +/- 1.2; M2: 1.4 +/- 0.7; P2; 1.7 +/- 1.3). No major adverse reaction was observed. Minor adverse effects occurred in 25.0% of cases in group M and 31.9% in group P (NS). The incidence in group P2 (44.4%) was significantly higher than those in group M1 (20.6%) and group P1 (8.3%). Remission rates did not differ between the MMI-treated group (35.0%, n=20) and PTU-treated group (50.0%, n=40). CONCLUSIONS: PTU may not be suitable for initial use in children and adolescents with GD, even with the risk of major adverse reactions such as liver failure excluded.