Background
Graves’ disease (GD), toxic multinodular goitre (TMNG), solitary toxic nodule (TN), and thyroiditis are common causes of hyperthyroidism. RAI is a well established definitive treatment option for hyperthyroidism, but considerable geographical variability remains in the choice of the preferred treatment modality, with RAI therapy used less commonly in Europe and Australia(1) as compared to the United States.(2)
Methods
We conducted a retrospective longitudinal study and included all patients newly diagnosed with hyperthyroidism at our Hospital’s outpatient clinic from January 2013 to June 2016. Case files were reviewed and patients receiving RAI therapy were further followed for a period of twelve months from the treatment date, to analyse the effectiveness as well as the occurrence of any treatment-related adverse effects.
Results
54 patients fulfilled the selection criteria (26 GD, 9 TMNG, 9 TN, 8 thyroiditis, 2 drug induced hyperthyroidism) and RAI therapy was utilised in 16 patients (7 GD, 5 TMNG and 4 TN). RAI dose ranged between 5 and 15mCi with 10mCi being the most commonly prescribed dose (11/16 patients). Hyperthyroidism resolved with RAI in 15/16 patients (11/11 with 10mCi, and 4/4 with 15mCi dose) with the mean time of resolution of 15 weeks. 3/16 patients (~19%) developed transient worsening of hyperthyroidism after RAI, and 6/16 patients (5/11 with 10mCi, and 1/4 with 15mCi dose) developed hypothyroidism within 12 months. Ophthalmopathy was observed in one patient receiving RAI therapy at baseline and no worsening was noted post therapy. RAI administration procedure was generally well tolerated by the patients.
Conclusion
Although the dose of RAI wasn’t uniform, doses between 10-15mCi were found to be effective and safe in our study. Hypothyroidism post-RAI was common and observed in almost a third of patients.
Despite the effectiveness and safety, RAI appeared to be the second line treatment option for hyperthyroidism in our study.