BACKGROUND
Thyroid nodules are common, occurring in up to 50% of the population. Most thyroid nodules work normally in that, while they can grow quite large, they do not produce excess thyroid hormone. However, 5-7% of thyroid nodules work on their own and do not turn off, leading to an overactive nodule. This is termed autonomously functioning thyroid nodule (AFTN). AFTNs secrete excess thyroid hormone, which can cause hyperthyroidism leading to symptoms such as palpitations, weight loss, tremors and anxiety. The standard treatment for AFTNs is surgical removal of the abnormal thyroid tissue or by administering radioactive iodine therapy, which significantly shrinks the nodule and helps treat hyperthyroidism. While effective, these treatments may lead to surgical complications, radiation exposure, and permanent hypothyroidism requiring lifelong thyroid hormone replacement.

A newer, much less invasive procedure called radiofrequency ablation (RFA) has emerged as an alternative treatment for thyroid nodules. RFA uses heat to destroy abnormal thyroid tissue while preserving healthy thyroid cells. Guided by ultrasound, the physician inserts a probe into the middle of the nodule and applies an electrical current to destroy the surrounding tissue. Originally developed to treat nonfunctional thyroid nodules, RFA could potentially treat AFTNs.

In this study, the authors evaluate the effectiveness of RFA in reducing the size of AFTNs and resolving hyperthyroidism while minimizing complications such as permanent hypothyroidism.

THE FULL ARTICLE TITLE
Dhanasekaran M, et al. Outcomes of radiofrequency ablation for autonomously functioning thyroid adenomas—Mayo Clinic experience. J Endocr Soc 2024;8(12)

SUMMARY OF THE STUDY
The authors reviewed the records of 22 patients who underwent RFA for a single autonomously functioning thyroid nodule at the Mayo Clinic between 2013 and 2021. Their main goal was to determine whether RFA could successfully treat hyperthyroidism in these patients. They also examined whether RFA reduced nodule size, improved symptoms, and caused any side effects or complications.

Of the 22 patients, 77% were female. Most (73%) had subclinical hyperthyroidism (low TSH but normal FT4), 9% had overt hyperthyroidism (low TSH and high FT4), and the remaining 18% had normal thyroid hormone levels but were on anti-thyroid drugs. Within 3 to 6 months after a single RFA treatment, 20 patients (91%) saw their TSH levels return to normal, indicating improvement in hyperthyroidism. Of the 2 patients with persistent hyperthyroidism, one underwent a second RFA treatment and achieved normal thyroid function. Nodule size decreased significantly in 21 out of 22 patients. Complications were rare — only two patients developed mild hypothyroidism requiring thyroid hormone replacement, and two patients experienced temporary worsening of their hyperthyroidism after treatment, but no life-threatening complications occurred.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This small study included patients who could afford a costly procedure. Additionally, a highly skilled radiologist with experience in thyroid imaging performed the RFA, but such specialists may not be widely available, thus making it challenging to expand the procedure. Despite this, the results suggest that RFA could effectively treat autonomously functioning thyroid nodules (AFTNs).

— Phillip Segal, MD

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