Endocrine Abstracts

Radioiodine is used for the treatment of hyperthyroidism and has been proven to be safe, efficacious and inexpensive. Despite the widespread use, there is a lack of consensus on many aspects of the treatment including aim, radioiodine dose, timing of the second dose and the role of antithyroid medication.

This was a retrospective study to investigate the outcome of radioiodine therapy in thyrotoxic patients. The aim was to determine the overall rate of successful cure of hyperthyroidism and compare this to available rates reported in the literature. We also aimed to investigate whether radioiodine dose received, underlying thyroid disease, or initial thyroid hormone levels predicted radioiodine therapy success or failure. Eighty nine patients treated with radioiodine in the period of 2000 to 2007 were identified and the results were analysed. Cure rate for all diagnoses in the time period was 84% (hypothyroid or euthyroid) and the success rate for Graves’ disease, multinodular goitre and toxic single nodule was 83, 95 and 77% respectively. There were more treatment failures at doses of <400 MBq (25%) when compared to any higher dose but results did not reach statistical significance.

The audit showed similar success rates when compared to published data with a trend towards higher success rates in patients given doses of >400 MBq. The greater failure rate in patients with a single toxic nodule is surprising but may reflect lower doses used (<400 MBq), although patient numbers were small. In line with current treatment recommendations from the Royal College of Physicians, the highest success rates were observed at doses of 400–499 MBq in Graves’ disease and 400–600 MBq for toxic multinodular goitres. Overall, 61% of patients became hypothyroid, during the period of follow-up. Thus it is important that patients are aware and appropriately counselled about the risks of hypothyroidism requiring lifelong thyroxine replacement.