ORIGINAL RESEARCH article
Front. Endocrinol.
Sec. Thyroid Endocrinology
This article is part of the Research TopicLevothyroxine Therapy in Patients with Hypothyroidism: Volume IIView all 22 articles
Levothyroxine Dose Prediction Post-Thyroidectomy for Differentiated Thyroid Carcinoma
Provisionally accepted
- Fujian Medical University Union Hospital, Fuzhou, China
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Objective: To address the overestimation of levothyroxine (L-T4) doses in conventional weight-based regimens for individuals who are overweight and obese, this study aimed to identify the most predictive body weight metrics and establish an optimized dosing model for accurate thyroid-stimulating hormone (TSH) suppression following total thyroidectomy in differentiated thyroid carcinoma (DTC). Methods: This retrospective study included 385 patients with DTC treated at our institution between October 2019 and December 2024. Patients were stratified by TSH targets (A1: <0.1 mIU/L; A2: 0.1–0.5 mIU/L; A3: 0.5–2.0 mIU/L) and body mass index (BMI) according to Chinese criteria (normal: <24 kg/m²; overweight: 24–27.9 kg/m²; obesity: ≥28 kg/m²). Linear regression analysis was used to analyze correlations between the final stable L-T4 dose and weight metrics, including total body weight, adjusted body weight, lean body weight, ideal body weight, and body surface area, followed by model validation. Model performance was internally validated using a hold-out method. Efficacy was estimated as the accuracy of the model-predicted dose compared with the actual dose required when a patient first achieved their TSH target within the first postoperative year. Results: The baseline characteristics showed no significant intergroup differences (P>0.05). Postoperative TSH levels varied significantly according to BMI (P<0.05). Patients with higher BMI required higher total L-T4 doses (µg/d) (P<0.001) but lower weight-adjusted doses (µg/kg/d) (P<0.001). Adjusted body weight best predicted L-T4 dose for patients with BMI≤23.9 kg/m2, while lean body weight was optimal for those with BMI≥24.0 kg/m2. The new model achieved a significantly higher rate of accurate initial dose prediction compared with that via empirical dosing (68.0% vs. 30.2%, P<0.001). Conclusion: The BMI-stratified L-T4 dosing formula based on optimized body weight metrics demonstrated improved accuracy, expediting TSH suppression and reducing adverse events.
Keywords: Differentiated thyroid carcinoma, Levothyroxine Dose Prediction, Overweight and obesity, Total thyroidectomy, TSH suppression therapy
Received: 18 Oct 2025; Accepted: 01 Dec 2025.
Copyright: © 2025 Ma, Xie, Ke, Liu, Wang, Wang and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Lijing Wang
Libin Liu
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