Purpose: Radioiodine (I131) therapy is the treatment mainstay for several benign and malignant thyroid disorders, however I131 is known to cause DNA damage and liberation of thyroidal self-antigens inducing secondary immunoreactivity. The exact mechanisms underpinning cellular death and subsequent induction of autoimmune thyroid disease following I131 treatment have not yet been fully elucidated. This manuscript aims to review the literature concerning the effects of I131 on the thyroid gland.Conclusion: The effects of I131 on malignant thyroid cells appears to depend on absorbed dose with the literature demonstrating a clear initial delay in the triggering of apoptosis in response to I131-mediated cellular damage. Some studies also observed necrotic cellular death following high-dose I131 treatment. Liberation of thyroidal self-antigen following I131 treatment helps to explain phenomena such as the subsequent induction of autoimmune thyroid disease. The clinical utility of cytokines and autoantibodies for prognostication of hypothyroidism and treatment failure following I131 remains uncertain and further appropriately-powered studies are required to clarify their role. The potential role of other cell death mechanisms activated after treatment with I131 should also be explored in order to fully delineate the thyroidal response.
Keywords: Thyroid gland; benign thyroid disorder; immune system; radioiodine therapy; thyroid neoplasms.