Microwave ablation of benign thyroid nodules: Two-year follow-up of thyroid function

Introduction: Microwave ablation (MWA) represents a minimally invasive alternative to surgical treatment of benign thyroid nodules. However, data on the long-term impact on thyroid function, particularly beyond one year of follow-up, remain limited. The aim: The aim of this study was to evaluate the impact of microwave ablation on thyroid function during a two-year follow-up period by analyzing changes in TSH, FT3, and FT4 values. Methods: This retrospective longitudinal cohort study included 39 patients with benign thyroid nodules confirmed by two independent fine-needle aspiration cytology findings. All patients were euthyroid prior to the procedure and were treated with microwave ablation between October 2022 and March 2026. Thyroid hormone values were analyzed before the procedure and at 12 and 24 months. Statistical analysis was performed using the Friedman test with post hoc Wilcoxon signed-rank test with Bonferroni correction. Results: Statistically significant changes were observed in TSH (p = 0.014), FT3 (p < 0.001), and FT4 (p < 0.001) during follow-up, with the most pronounced differences between 12 and 24 months. Nevertheless, hormone values remained within reference ranges in the majority of patients. No clinically significant thyroid dysfunction requiring therapy was observed. Conclusion: Microwave ablation is a safe and effective method for the treatment of benign thyroid nodules with minimal long-term impact on thyroid function. Although statistically significant changes in hormone values may occur, they rarely have clinical significance. The results support the use of MWA as a thyroid-preserving method, with a recommendation for continued patient follow-up.