Standard-dose Prescription of Radioiodine Therapy for Thyrotoxicosis: the Queen Mary Hospital Experience

C Kwok, L Lui, PM Wu, M Law, E Cheung, A Cheng, CC Yau

Hong Kong J Radiol 2004;7:187-94

Objective: To review the treatment outcome of a cohort of thyrotoxic patients treated with a standardised regimen of radioactive iodine.

Patients and Methods: Between January and December 2000, a total of 177 patients with a diagnosis of thyrotoxicosis were referred to the Department of Clinical Oncology, Queen Mary Hospital, for radioactive iodine therapy. Patients’ clinical records, thyroid function test results, and records of dispensed drugs were analysed to identify predictors of successful treatment outcome.

Results: For the 149 patients who were eligible for analysis, the 1-year treatment success rate, defined as the proportion of patients who had become euthyroid or hypothyroid at 1 year after the first dose of radioactive iodine treatment, was 66%. Use of an antithyroid drug in the early post-treatment period was significantly associated with treatment failure. The cumulative rate of hypothyroidism at 1, 2, and 3 years after therapy was 57%, 66%, and 73%, respectively.

Conclusion: The treatment results of the cohort of patients are comparable to those of patients treated in our institute using the prescribed absorbed dose method. Because the fixed-radioactivity method of prescription is much less resource-intensive and more userfriendly, we recommend its continued adoption as a routine practice.