Endocrine Abstracts

Background: The short- and long-term clinical outcome of patients receiving radioactive iodine treatment (RAI) differs in various studies. There is little consensus regarding the most appropriate dose of RAI to be administered. The range of activities currently prescribed varies between 200 and 800 MBq, with majority of patients receiving 400–600 MBq. In our centre, all patients receive a standard fixed dose of 400 MBq.

Aim: To assess the cure rate with fixed dose (400 MBq) RAI therapy.

Patients and methods: This is a retrospective study of all patients treated with RAI at this hospital over a 3-year period. All patients received a fixed 400 MBq dose. TSH and FT₄ levels were recorded at diagnosis, the time of RAI, 6 months and 1-year post-RAI. Anti-thyroid medication was discontinued for 10 days prior to RAI therapy. Failure rate in terms of persistence of hyperthyroidism at the end of 6 months and 1 year was calculated.

Results: Mean age was 59 years (range: 25–88 years). Of the total 59 patients, 16 (27.12%) were male and 43 (72.88%) were female, 19 (32.2%) had Graves’ disease, 19 (32.2%) had multi-nodular disease and in 21 (35.5%) patients, thyrotoxicosis was of unknown aetiology. At the time of diagnosis, 37% (22 patients) had goitre, 14% (eight patients) had thyroid ophthalmopathy, 22% (13 patients) were positive for antiTPO antibody and 94.91% (56 patients) were pre-treated with anti-thyroid drugs. 48 patients (81.36%) were either hypothyroid (28 patients, 47.45%) or euthyroid (20 patients, 33.89%) at 6 months. 11 patients (18.6%) were hyperthyroid at 6 months. At 12 months, 45 patients (76.27%) were either hypothyroid (12 patients, 20.3%) or euthyroid (33 patients, 55.9%) and 14 patients (23.7%) had persistence of hyperthyroidism.

Conclusion: In our centre, a standard 400 MBq dose of RAI has a cure rate of 81.36% at 6 months and 76.27% at 12 months, which is in line with the figures quoted in the literature.