OR06-07 Leptin Alterations After Radioactive Iodine Treatment of Graves Disease

Abstract Disclosure: A.E. Mammadova: None. Introduction: Graves' disease is a common autoimmune thyroid disorder, affecting an estimated 0.5% of men and 3% of women. Radioactive iodine therapy is frequently employed as a definitive treatment for Graves' disease due to its efficacy in ablating overactive thyroid tissue. Radioactive iodine therapy is a frequently used treatment for Graves' disease, but its impact on metabolic parameters, including leptin levels, remains incompletely understood. Leptin, a key regulator of appetite and energy expenditure, may be influenced by RAI-induced changes in thyroid hormone status. Aim: To assess the alterations in serum leptin levels following RAI therapy in patients with Graves' disease, and to explore the potential influence of disease duration and prior methimazole use on these changes, to identify patients at higher risk of metabolic complications. Materials and Methods: The research was conducted using the principles of the Helsinki Declaration and was approved by the Health Research Ethics Committee of AM University. After an explanation of the aim of the study, written informed consent was received from each participant. This prospective cohort study, conducted at the National Oncology Center's Department of Nuclear Medicine between 2023 and 2024, evaluated serum leptin levels of 62 patients with Graves' disease before and after 12 months of radioactive iodine treatment. Leptin concentrations were measured using a radioimmunoassay. (Radioimmunoassay, 2024) Results: Leptin levels increased significantly following RAI, reaching a peak of 26.6 ±1.6 ng/mL at 12 months (p < 0.001). This increase in leptin levels positively correlated with TSH levels (r = 0.7, p < 0.001) Furthermore, patients with a disease duration exceeding 12 months and a history of prolonged methimazole use demonstrated a greater increase in leptin levels post-RAI (p < 0.05). Conclusion: RAI therapy for Graves' disease leads to a significant increase in circulating leptin levels, particularly in patients with longer disease duration and prior methimazole use. This hormonal shift may contribute to metabolic changes and weight gain observed in patients following RAI, warranting further investigation into its clinical implications and potential management strategies, especially in this higher-risk subgroup. This clarifies the impact of disease duration and methimazole use on leptin levels after RAI and highlights the possible need for tailored management in these patients. Presentation: Saturday, July 12, 2025