Endocrine Abstracts

JOINT1575

Purpose: To investigate the optimal initial dose of methimazole (MMI) in the treatment of pediatric Graves’ disease (GD).

Methods: A retrospective analysis was conducted on clinical data from GD patients treated at our hospital between December 2015 and August 2023. Patients were further divided into low-dose (< 0.5 mg/kg/d) and high-dose (≥ 0.5 mg/kg/d) groups. A restricted cubic spline logistic regression analysis was used to assess the nonlinear relationship between the initial dose and the probability of normalizing free thyroxine (FT₄) within 30 days.

Results: The 324 GD patients ranged in age from 2.1 to 16.1 years. The mean initial doses for the mild, moderate, and severe groups in the low-dose and high-dose groups were 0.32±0.09 vs. 0.73±0.19, 0.39±0.08 vs. 0.71±0.18, and 0.35±0.09 vs. 0.73±0.17 mg/kg/d, respectively. There was no significant difference in the time to normalize FT₄ between the low-dose and high-dose groups for different severity categories (P >0.05); however, the results of linear analysis showed that thyroid volume, initial dose and disease severity affected the days for FT₄ to return to normal. After adjusting for these factors, there was a nonlinear relationship between the initial MMI dose and the probability of normalizing FT₄ within 30 days, with the probability increasing until reaching a plateau at a dose of 0.58 mg/kg/d.

Conclusion: For patients with mild disease, an initial dose of 0.3 mg/kg/d is recommended. For those with moderate to severe disease, an initial dose of 0.5 to 0.6 mg/kg/d is recommended.