Radioactive Iodine Therapy in Transition: Lessons from the 2024 Korean Thyroid Association and 2025 American Thyroid Association Guidelines

The role of radioactive iodine (RAI) therapy in differentiated thyroid cancer (DTC) has changed substantially, moving from routine postoperative administration toward a more individualized, risk-adapted strategy.The sequential publication of the 2024 Korean Thyroid Association (KTA) guidelines on the management of DTC [1] and the 2025 American Thyroid Association (ATA) management guidelines for adult patients with DTC [2] provides an opportunity to examine how international recommendations for RAI therapy are evolving.Although the two guidelines were developed within different health care systems, reimbursement structures, and clinical practice environments, they present a broadly convergent approach: selective de-escalation of RAI treatment in low-risk disease, risk-adapted activity selection, broader use of recombinant human thyroidstimulating hormone (rhTSH) preparation, and greater integration of hybrid single-photon emission computed tomography/ computed tomography (SPECT/CT) into post-therapy evaluation.The central message of these guideline updates is not a simple reduction in RAI use but a more precise alignment of the therapeutic purpose, administered activity, preparation method, and post-therapy assessment with recurrence risk and disease status.This commentary summarizes key changes, shared principles, and remaining differences between the two guidelines regarding RAI use in the initial management of DTC.