BACKGROUND
Hyperthyroidism is a condition whereby the thyroid gland becomes overactive and makes too much thyroid hormone. While Graves’ disease is the most common cause of hyperthyroidism, overactive (“hot”) thyroid nodules are also an important cause. This can be due to a single overactive nodule or multiple overactive nodules. Hyperthyroidism due to overactive nodules often includes treatment with antithyroid medications followed by more permanent solutions such as radioactive iodine therapy or surgical removal. This is because overactive thyroid nodules do not go into remission, as is seen with Graves’ disease. Radioactive iodine therapy or surgical removal carry risks including development of hypothyroidism (especially if there are multiple overactive thyroid nodules) or surgical complications.

Thermal ablation has emerged a technique to destroy overactive nodules in hopes of restoring normal thyroid function without the potential side effects of the other options. Radiofrequency ablation (RFA) is a technique whereby radiofrequency electrical currents are applied to tissue to cause tissue destruction. In the case of overactive thyroid nodules, radiofrequency current is applied to the nodule to cause nodule tissue destruction resulting in nodule shrinkage and resolution of hyperthyroidism. This study examined the safety and efficacy of radiofrequency ablation in hyperthyroid patients with a single overactive thyroid nodule.

THE FULL ARTICLE TITLE
Dueñas JP et al. Radiofrequency ablation for solitary autonomously functioning thyroid nodules: multicenter study from Latin America. Thyroid. Epub 2024 Dec 19; doi:10.1089/thy.2024.0338. PMID: 39699644.

SUMMARY OF THE STUDY
The study looked at patients that underwent RFA for treatment of a single overactive thyroid nodule. A total of 81 patients from several Latin American countries were included in the study. All patients had hyperthyroidism (79 of 81 patients; 97.5%) or subclinical hyperthyroidism (2 patients) due to a single overactive nodule that had been determined to be noncancerous by thyroid biopsy.

All underwent RFA using standard techniques at each institution and followed after RFA for a decrease in nodule size, resolution of hyperthyroidism and any complications. Data was collected at 1, 3, 6, 12, 18, and 24 months following the RFA.

RFA was associated with high clinical success; many nodules shrank in size over time, and most patients had resolution of their hyperthyroidism. In all, 76 of 81 patients (93.8%) had normalization of their thyroid function, with most occurring in the first month after treatment (47 of 81; 58%). The clinical response rate was not different between patients with smaller or larger nodules as has been seen in prior studies, but did correlate with the degree of nodule shrinkage. RFA was associated with a low complication rate (5 of 81 patients, 6.2%) and included 1 patient with Horner’s syndrome (nerve damage that affects face and eye), 3 cases of transient voice changes and 1 case of hypothyroidism. In general, the procedure was well tolerated and associated with normalization of thyroid function in most patients. Given the relatively short duration of the study follow up, it is unclear whether the patients would all remain with normal thyroid function over time but results so far suggest that this may be a promising treatment option for hyperthyroidism caused by single overactive thyroid nodule.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that hyperthyroidism caused by a single overactive thyroid nodule can be treated effectively by RFA. This procedure is not associated with some of the risks that can occur with surgical removal. Successful treatment of hyperthyroidism is associated with reduction in nodule size following RFA. This procedure is well tolerated, successful at restoring normal thyroid function and has a lower rate of hypothyroidism than radioiodine ablation or surgery. Although a promising procedure, the durability of this treatment is currently unclear, and more studies are needed to further evaluate long term safety and efficacy.

— Whitney W. Woodmansee MD

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