After total thyroidectomy for pediatric differentiated thyroid cancer (DTC), the subsequent radioactive iodine (RAI) treatment is a robust therapy, the dosing of which is a major concern. This study was designed to evaluate the "as high as safe administration" (AHASA) principle of RAI treatment in pediatric DTC patients based on the maximum tolerance activity (MTA) of blood to certify dosimetry via a simple algorithm method. Twenty pediatric DTC patients were enrolled and received RAI treatment empirical dosing based on risk stratification after total thyroidectomy. The MTA concentration in the blood was estimated by the modified Hänscheid equation. About 6 (30%) patients had tumors larger than 4 cm, 10 (50%) patients had lateral cervical lymph node metastasis, and 4 (20%) patients had recurrent/persistent thyroid cancer and received more than two RAIs. Five (25%) pediatric patients who had higher serum thyroglobulin antibodies levels at initial diagnosis exhibited aggressive clinical manifestations. Body weight-based doses showed wide variability, and the Dutch recommended dose showed underdosing. In addition, lower body weight was associated with a significantly higher blood absorption dose (R² = 0.3849, p = 0.014). No severe adverse effects were observed in patients who received empirical RAI dosage according to the AHASA principle. The presentation of pediatric DTC can be advanced and aggressive. Empirical RAI dosing based on risk stratification is a simple, safe and effective method. In compliance with the AHASA principle, for prepubertal patients with very low body weight, it is necessary to calculate the blood MTA for RAI dose adjustment.

Keywords: as high as safe administration (AHASA) principle; maximum tolerance activity (MTA); pediatric differentiated thyroid cancer (DTC); radioactive iodine (RAI) treatment; simple method algorithm.

© 2025 The Author(s). The Kaohsiung Journal of Medical Sciences published by John Wiley & Sons Australia, Ltd on behalf of Kaohsiung Medical University.

在接受全甲状腺切除术治疗儿童分化型甲状腺癌（DTC）后，后续的放射性碘（RAI）治疗是一种强有力的疗法，其剂量是主要关注的问题。本研究旨在根据血清最大耐受活性（MTA）通过简单算法方法验证儿科DTC患者中RAI治疗“尽可能安全”的给药原则。纳入了20名儿童DTC患者，并在接受全甲状腺切除术后基于风险分层接受经验性剂量的RAI治疗。使用改良的Hänscheid方程估计血清中的MTA浓度。大约6（30%）患者的肿瘤直径大于4厘米，10（50%）患者有侧颈淋巴结转移，而4（20%）名患者有多次复发或持续性甲状腺癌并接受了超过两次的RAI治疗。初始诊断时血清甲状腺球蛋白抗体水平较高的五（25%）名儿科患者表现出更具侵袭性的临床表现。根据体重调整剂量显示出较大的变异范围，且荷兰推荐剂量出现给药不足的情况。此外，较低的体重与显著更高的血液吸收剂量相关（R² = 0.3849, p = 0.014）。接受基于“尽可能安全”原则的经验性RAI剂量治疗的患者中未观察到严重的不良反应。儿童DTC的表现可以是进展迅速且侵袭性强。基于风险分层的经验性RAI给药是一种简单、安全和有效的治疗方法。遵循AHASA原则，对于体重非常低的学龄前患儿，在调整RAI剂量时需要计算血液MTA。

关键词：尽可能安全给药（AHASA）原则；最大耐受活性（MTA）；儿童分化型甲状腺癌（DTC）；放射性碘（RAI）治疗；简单方法算法。