• Autonomously functioning thyroid nodule
• Radiofrequency Ablation
• Radioiodine therapy

Abstract
Purpose
To compare the efficacy of Radioiodine (RI) and Radiofrequency ablation (RFA) in the treatment of autonomously functioning thyroid nodules (AFTNs). End points: nodule volume reduction (NVR) and thyroid function normalization.

Materials and methods
Twenty-two patients (2:20 M:F; 51.9±13.9 years) affected by 25 AFTN and treated by RFA were compered with 25 patients (8:17 M:F; 57.2±12.8 years) affected by a single AFTN treated by RI. The series of patients included in each group showed analogous characteristics as to age, gender, toxic/pretoxic phase, and pre-treatment nodule volume. The thyroid hormone levels and the autoimmune thyroid profile were assessed before the treatment. The RI dose administered was 15 mCi; RFA was performed with an 18G, single-tipped electrode, by applying the ‘modified moving shot technique’. Twelve months after treatment, the thyroid hormones were assessed again and the nodule post-treatment volume was calculated.

Results
No statistical difference was found between the post-treatment nodule volumes by comparing RI and RFA (p=0.69). The volume reduction rates were 68.4±28.9% and 76.4±16.9% after RI and RFA, respectively. As to the thyroid function, after RI, 5/25 patients developed clinical hypothyroidism. After RFA, all the 22 patients silenced their AFTN and normalized the thyroid hormones.

Conclusions
No statistical difference in NVR was found between RI and RFA. All patients responded to RI but 5/25 were ‘over-treated’ developing hypothyroidism (20%). RFA was effective in all patients with no case of post-treatment clinical hypothyroidism. Thus, the absence of radiation exposure and the lower risk of post-treatment hypothyroidism made RFA the favorite option especially for young patients.