The effect of radioiodine treatment on the diseased thyroid gland

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.