Endocrine Abstracts

Introduction: Radioactive iodine -131 (RAI) has been used to treat hyperthyroidism for the past eight decades.[1] Despite this, controversy remains regarding radiation dosage.[2] The National Institute for Health and Care Excellence (NICE) recommends fixed dose regime with varying doses depending on underlying thyroid condition.[3] The European Journal of Nuclear Medicine and Molecular Imaging (EANM) offers similar guidance.[4] We offered all our patients single dose of 400MBq rather than variable doses irrespective of underlying thyroid condition causing hyperthyroidism. This audit aims to assess the outcomes for patients with benign thyroid disease after receiving a single dose (400MBq) of RAI at a single secondary care centre.

Method: Patients who underwent RAI at Sunderland Royal Hospital were identified retrospectively by electronic clinic notes over a 15-month period. In addition to patient demographics, details extracted included the indication for RAI, thyroid state, dose received, and the clinical outcome of RAI. If applicable, the length of remission and whether any further doses of RAI were required were also recorded.

Results: 102 patients underwent RAI between June 2022 and September 2023. 53 (51.9%) patients had a multinodular goitre (MNG), 48 (47%) had Graves’ Disease and 1 (0.9%) had a toxic adenoma. 92 patients (90.2%) went into remission, just greater than half of which were subsequently euthyroid. The remaining were hypothyroid following their RAI. 10 patients (9.8%) failed to go into remission, 8 of which had Graves’ disease and 2 had a MNG.

Discussion: This audit has highlighted the large percentage of patients went into remission after receiving a fixed dose of RAI (400MBq) irrespective of underlying cause of hyperthyroidism. In turn, the small proportion of patients who failed to achieve remission has reinforced the efficacy of a single dose of RAI in the treatment of benign thyroid disease. Following on from this, reauditing outcomes at multiple centres aims to gain a greater understanding of RAI outcomes in the context of benign thyroid disease.References1. Campennì, A., Avram, A.M., Verburg, F.A. et al. The EANM guideline on radioiodine therapy of benign thyroid disease. Eur J Nucl Med Mol Imaging 50, 3324–3348 (2023). 2. Jaiswal AK, Bal C, Damle NA, Ballal S, Goswami R, Hari S, Kumar P. Comparison of clinical outcome after a fixed dose versus dosimetry-based radioiodine treatment of Graves’ disease: Results of a randomized controlled trial in Indian population. Indian J Endocrinol Metab. 2014 Sep;18(5):648-54. van Isselt JW, de Klerk JM, Lips CJ. Radioiodine treatment of hyperthyroidism: fixed or calculated doses; intelligent design or science? Eur J Nucl Med Mol Imaging. 2007 Nov;34(11):1883-4. 3. Thyroid disease: Assessment and management (no date) NICE. Available at: https://www.nice.org.uk/researchrecommendation/long-term-effectiveness-and-safety-of-radioactive-iodine-therapy-for-hyperthyroidism (Accessed: 02 October 2024). 4. Campennì, A., Avram, A.M., Verburg, F.A. et al. The EANM guideline on radioiodine therapy of benign thyroid disease. Eur J Nucl Med Mol Imaging 50, 3324–3348 (2023).