Clinical efficacy of fixed-dose radioactive iodine for the treatment of hyperthyroidism at a single centre: our experience.

Background: Iodine-131 is an effective treatment for thyrotoxicosis. In 2019, National Institute for Clinical Excellence guidelines (UK) suggested offering radioactive iodine as first-line definitive treatment for adults with Graves' disease, toxic nodular and multinodular goitre unless it is unsuitable or anti-thyroid drugs are likely to achieve remission. The aim of this study was to evaluate the clinical outcome 1 year after using fixed-dose Iodine-131 for hyperthyroidism and time (months) to response.

Methods: Electronic patient records were studied retrospectively for all patients who were treated with radioiodine therapy for hyperthyroidism between July 2017 and March 2020 at a district general hospital in the UK. Response to radioiodine therapy was initially assessed at 6 weeks and then at 3, 6, and 12 months by a dedicated thyroid nurse-led virtual follow-up.

Results: We identified 67 patients with a mean age of 55.9 years (range 18-84); 48 (72%) females, 19 (28%) males. Of these, 57 (85%) patients were cured at 12 months (93.7% in non-Graves', 82.3% in Graves' group). Gender, diagnosis and pre-treatment disease interval were not significantly associated with treatment success. Non-Graves' patients had a significantly shorter time to discharge than Graves' patients receiving Iodine-131 (8 versus 10.3 months, p = 0.0174).

Conclusion: The results of the present study demonstrate that a single fixed dose of Iodine-131 therapy is highly effective and comparable to outcomes from calculated dose therapy in literature. We propose the routine use of scoring system to calculate risk of relapse for all newly diagnosed hyperthyroid patients to tailor treatment modality.