Incidence and predictors of spontaneous thyroid-stimulating hormone normalization after lobectomy for low-risk papillary thyroid microcarcinoma: evidence from contemporary clinical practice.

Objective: To investigate spontaneous thyroid-stimulating hormone (TSH) normalization (TSH ≤ 2 μIU/mL) and its predictors in patients with low-risk papillary thyroid microcarcinoma (PTMC) who underwent unilateral lobectomy without pharmacological intervention. Methods: This retrospective study enrolled 411 low-risk PTMC patients who underwent unilateral lobectomy. Clinical, pathological, and preoperative biochemical data were collected, including thyroid function tests (fT3, fT4, TSH), thyroglobulin (Tg), and thyroid autoantibodies (TPO-Ab, Tg-Ab). TSH levels were monitored at 0.5, 1.5, 6, and 12 months postoperatively. Binary logistic regression and ROC curve analyses were used to identify preoperative predictors of spontaneous TSH normalization at 12 months. Results: The rate of spontaneous TSH normalization progressively declined: 32.4% at 0.5 months, 20.2% at 1.5 months, 14.8% at 6 months, and 12.4% at 12 months. In contrast, TSH target achievement with thyroid hormone therapy increased over time, reaching 100% at 12 months. Patients with spontaneous normalization at 12 months were younger, had higher preoperative fT3, and lower preoperative TSH (all Conclusion: Approximately 12.4% of low-risk PTMC patients achieved spontaneous TSH normalization within one year after lobectomy, obviating hormone replacement. A preoperative TSH ≤ 1.7 μIU/mL serves as a useful predictor, supporting individualized management by deferring or avoiding levothyroxine supplementation in eligible patients.