Does Radioactive Iodine Treatment Affect Thyroid Size and Tracheal Diameter?

Background/Objectives: There exist three principal treatment modalities employed in the management of hyperthyroidism attributable to excessive hormone secretion by the thyroid gland: antithyroid pharmacotherapy, surgical intervention, and radioactive iodine (RAI) therapy. Surgical intervention is typically indicated for markedly enlarged thyroid glands that exert pressure on the trachea. The objective of this investigation was to ascertain the influence of RAI on thyroid volume and tracheal diameter. Methods: This study included 20 patients, six females and 14 males, who received 20 mCi radioactive iodine treatment for toxic nodular goiter at a tertiary university hospital between March 2019 and February 2020. Pre-treatment and six-month post-treatment neck MRI scans were conducted on the cohort. Thyroid and tracheal volumes were quantified using the Cavalieri method based on MRI sections, and comparisons were conducted pre-and post-treatment. Statistical analysis of the comparative values was performed using the dependent samples t-test. Results: A statistically significant reduction in thyroid volume was observed among the 20 patients, averaging a decrease of 36.06% following RAI treatment compared to baseline measurements (p < 0.001). Additionally, an average increase of 12.76% in tracheal volume was noted post-treatment in comparison to initial measurements, which was also statistically significant (p < 0.05). None of the patients exhibited respiratory distress in the immediate postoperative period. Conclusions: The findings indicate that RAI therapy leads to a reduction in thyroid size, accompanied by an increase in tracheal diameters subsequent to treatment. Given the potential complications and risks associated with surgical intervention, it may be prudent to consider large thyroids for RAI therapy as an alternative to surgery.