Endocrine Abstracts

Hyperthyroidism is common and in iodine-sufficient parts of the world the prevalence of overt hyperthyroidism is estimated to be 0.2% to 1.3%. The treatment options include antithyroid medication (ATD), thyroid surgery, or Radioactive iodine (RAI). The latter is increasingly used as a first line definitive treatment for hyperthyroidism. We reviewed the outcomes of patients who received RAI at our tertiary nuclear medicine department over a 4-year period (May 2015 to Dec 2019) and who are under the care of our unit to ensure we have relevant follow up data. We identified 146 Patients who received RAI: 119 Female (82%), 27 Male (18%) with a mean age of 51.3 years. 45.9 % of patients had Grave’s Disease, 11.7% had single toxic adenoma (STA), 40.4% had Toxic Multinodular Goitre (MNG) and 2% had mixed disease (MNG & Graves). Outcome post-RAI: 129 patients (88.3%) achieved remission from thyrotoxicosis after a single dose. 7.5% (5 patients with Graves’ disease -GD, and 6 patients with MNG) needed 2 doses of RAI to achieve remission. 5 patients (3.4%; 3 with MNG, one patient with mixed disease, and one with GD) did not respond after 2 doses of RAI and were still on ATD. The remission rates after the first dose per diagnosis were: 91 % for GD, 83 % for MNG, 66% for mixed disease, and 100% for STA. 74.6% of the treated patients developed permanent hypothyroidism after responding to RAI. The risk of developing hypothyroidism was higher in GD patients who responded to treatment, of who 95.5% developed hypothyroidism, followed by patients who had STA (82.3%) with only 47.5 % of patients with MNG developing subsequent hypothyroidism. The average time to develop hypothyroidism after RAI was 3.6 months, however, this tended to be longer with patients who had MNG. In conclusion, RAI is an effective treatment for thyrotoxicosis, which is associated with a high rate of hypothyroidism and a small rate of failure. Our Patients were closely followed up post-treatment as per standard recommendations.