Changes of Thyroid Antibodies After Thermal Ablation of Thyroid Nodules: A Retrospective Study

Song LiYing WeiZhen-long ZhaoLi-li PengYan LiMing-an Yu^*

• China-Japan Friendship Hospital, Beijing, China

Context: Thermal ablation (TA) is increasingly used as a minimally invasive treatment for thyroid nodules; however, its influence on thyroid autoimmunity remains unclear. Objective: To investigate longitudinal changes in thyroid autoantibodies and identify relevant risk factors. Methods: This retrospective study included 222 patients who underwent TA between April 2020 and September 2023. Serum levels of anti-thyroglobulin antibody (TGAb), anti-thyroid peroxidase antibody (TPOAb), and thyrotropin receptor antibody (TRAb) were measured at baseline and at 1, 6, 12, and 24 months post-ablation. Antibody trajectories, abnormality rates, and associated risk factors were analyzed. Results: TGAb and TRAb levels increased significantly at all post-ablation time points compared to baseline (all p < 0.05), while TPOAb showed a delayed but significant elevation beginning at 6 months. New-onset antibody positivity was observed in 16.2% of patients, including 9.0% with transient elevations, 4.1% with persistent positivity, and 3.2% with late-onset elevation. Among patients with transient elevations, 93.1% normalized within 24 months. At the 1-month follow-up, patients with benign nodules had more frequent antibody abnormalities than those with papillary thyroid carcinoma (9.5% vs. 2.7%, p = 0.045), although no significant differences were observed at subsequent time points. Multivariate analysis identified papillary thyroid carcinoma (OR = 7.70, p = 0.035), baseline TGAb (OR = 1.08, p < 0.001), and baseline TPOAb (OR = 1.12, p = 0.023) as independent predictors of post-ablation antibody abnormalities. ROC analysis demonstrated that a baseline TGAb level ≥17.32 IU/mL had moderate predictive value (AUC = 0.746), with a specificity of 85.5% and a negative predictive value of 91.9%. Conclusion: Thermal ablation was associated with transient increases in thyroid autoantibodies. A baseline TGAb level ≥17.32 IU/mL, elevated TPOAb, and a diagnosis of papillary thyroid carcinoma are associated with increased risk.