左旋甲状腺素 (LT4) 单药疗法是目前推荐的治疗全甲状腺切除术 (TT) 后儿科患者的方法，其假设是外周甲状腺素 (T4) 转化为三碘甲状腺原氨酸 (T3) 可使甲状腺激素水平正常化。在成人中，大约 15% 接受 LT4 单一疗法的 TT 后患者的 T4:T3 比率发生了改变，关于健康相关生活质量 (hrQOL) 的临床影响的争论仍在继续。对于儿科患者的 TT 后，LT4 单一疗法使 T3 和 T4 水平正常化的能力很重要，但之前没有描述过。本研究报告了甲状旁腺症儿科患者 T3 水平的数据，以确定是否存在类似的接受 LT4 单一疗法的患者，目标是 TSH 正常化（LT4 替代）或抑制（LT4 抑制）。从医学图表中回顾性提取甲状腺功能测试 (TFT)适用于 2010 年至 2021 年间接受 TT 治疗格雷夫斯病 (GD) 或分化型甲状腺癌 (DTC) 的 19 岁以下患者。选择 LT4 剂量来使 GD 患者的 TSH 正常化（LT4 替代）或抑制 DTC 患者的 TSH（LT4 抑制）。比较手术前和手术后的 TSH、T3 和 T4 水平。在 108 名接受 LT4 替代 (n=53) 或 LT4 抑制 (n=55) 治疗的患者中，94% (102/108) 的患者表现出 T3 水平TT 后的正常范围。然而，大多数接受 LT4 替代（44/53；83%）和 LT4 抑制（31/55；56%）的患者显示 TT 后 T3 水平处于正常范围的下半部分，尽管有 50%（22/44）这些患者中分别有 48% (15/31) 的 TT 后 fT4 水平高于正常范围的上限。大量儿童患者在治疗前和治疗后未达到相似的 T3 和 T4:T3 水平。 TT。未来需要进行多中心、前瞻性研究来评估 LT4 单一疗法与 LT4/LT3 联合疗法的比较，以确定 T3 水平改变对甲状旁腺症儿科患者的潜在临床影响。版权所有 © 2024 Baran、Isaza、Bojarsky、Alzoebie、Song、Halada，西斯科、冈萨雷斯、莫斯托菲-莫阿布和鲍尔。

Levothyroxine (LT4) monotherapy is the current recommended approach for treating pediatric patients post-total thyroidectomy (TT) based on the assumption that peripheral conversion of thyroxine (T4) to triiodothyronine (T3) normalizes thyroid hormone levels. In adults, approximately 15% of post-TT patients on LT4 monotherapy have altered T4:T3 ratios with ongoing debate in regard to the clinical impact with respect to health-related quality of life (hrQOL). The ability to normalize T3 and T4 levels on LT4 monotherapy for pediatric patients' post-TT is important but not previously described. This study reports data on T3 levels in athyreotic pediatric patients to determine if a similar cohort of patients exists on LT4 monotherapy targeting normalization of TSH (LT4 replacement) or suppression (LT4 suppression).Thyroid function tests (TFTs) were retrospectively extracted from medical charts for patients <19 years old who underwent TT for definitive treatment of Graves' disease (GD) or differentiated thyroid cancer (DTC) between 2010-2021. LT4 dosing was selected to normalize the TSH in GD patients (LT4 replacement) or suppress TSH in DTC patients (LT4 suppression). Pre- and post-surgical TSH, T3 and T4 levels were compared.Of 108 patients on LT4 replacement (n=53) or LT4 suppression (n=55) therapy, 94% (102/108) of patients demonstrated T3 levels in the normal range post-TT. However, the majority of patients on LT4 replacement (44/53; 83%) and LT4 suppression (31/55; 56%) displayed post-TT T3 levels in the lower half of the normal range despite 50% (22/44) and 48% (15/31) of these patients, respectively, having post-TT fT4 levels above the upper limit of the normal range.A significant number of pediatric patients do not achieve similar T3 and T4:T3 levels pre- and post-TT. Future multi-center, prospective studies evaluating LT4 monotherapy in comparison to combined LT4/LT3 therapy are warranted to determine the potential clinical impact of altered T3 levels in athyreotic pediatric patients.Copyright © 2024 Baran, Isaza, Bojarsky, Alzoebie, Song, Halada, Sisko, Gonzales, Mostoufi-Moab and Bauer.