Thyroid Dysfunction Following Thermal Ablation of Large Solid and Solid-Predominant Thyroid Nodules.

Objectives: Thermal ablation (TA) is an alternative to lobectomy for thyroid nodules (TNs). While it is believed that thyroid function remains stable after TA for cystic TNs, the impact of TA on solid TNs, especially the large ones, is less explored. This study investigates changes in thyroid hormones after TA in patients with solid-predominant TNs and identifies potential risk factors for thyroid dysfunction after TA.

Methods: Euthyroid patients with solid-predominant TNs (≥80% solid) were enrolled. The volume, diameter, and cytopathology of TNs were assessed before TA. TA was performed using either microwave or radiofrequency ablation. Thyroid hormone levels were measured at 1 week and 1, 3, 6, and 12 months after TA.

Results: 77 euthyroid patients with TNs were included. The euthyroid rate dropped to 70.1% at 1 week after TA but improved to over 90% by 1 month and returned to 100% by 12 months. At 1 week after TA, subclinical hyperthyroidism and hyperthyroidism were observed, with elevated T4, fT3, fT4, and TGAb levels, along with decreased TSH levels. The diameter and total volume of TNs were positively correlated with thyroid dysfunction, while TSH-baseline was negatively correlated with thyroid dysfunction 1 week after TA. A larger diameter and lower baseline TSH were identified as independent risk factors for thyroid dysfunction.

Conclusions: TA may cause short-term thyroid dysfunction, especially in patients with large TNs. Monitoring of thyroid hormone levels is recommended from 1 week to 3 months after TA to manage potential thyroid dysfunction effectively.