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.

Approach:

• Study Design: Retrospective study enrolling 411 low-risk PTMC patients who underwent unilateral lobectomy, collecting clinical, pathological, and preoperative biochemical data.
• Data Collection: Thyroid function tests (fT3, fT4, TSH), thyroglobulin (Tg), and thyroid autoantibodies (TPO-Ab, Tg-Ab) were monitored at 0.5, 1.5, 6, and 12 months postoperatively.
• Statistical Analysis: Binary logistic regression and ROC curve analyses were used to identify preoperative predictors of spontaneous TSH normalization at 12 months.

Key Findings:

• Spontaneous TSH normalization rates were 32.4% at 0.5 months, 20.2% at 1.5 months, 14.8% at 6 months, and 12.4% at 12 months (all P < 0.05).
• TSH target achievement with thyroid hormone therapy reached 100% at 12 months.
• Patients with spontaneous normalization at 12 months were younger, had higher preoperative fT3, and lower preoperative TSH (all P < 0.05).
• Preoperative TSH ≤ 1.7 μIU/mL was identified as an independent predictor for TSH normalization.

Interpretation:

Limitations:

• The study was retrospective and conducted at a single center, which may limit generalizability.
• Exclusion criteria may have led to selection bias.

Conclusion:

A preoperative TSH ≤ 1.7 μIU/mL serves as a useful predictor for spontaneous TSH normalization.