Efficacy of Radioiodine Therapy in Patients With Primary Hyperthyroidism: An Institutional Review From Pakistan

Background Radioactive iodine (RAI) is the treatment of choice for most patients with primary hyperthyroidism. The most common etiologies of hyperthyroidism are Graves' disease (GD), toxic adenoma (TA), and toxic multinodular goiter (TMNG). A single dose of RAI is usually sufficient to cure hyperthyroidism. The aim of this study was to assess the effectiveness of RAI therapy for patients diagnosed with primary hyperthyroidism. Methods and materials Patients diagnosed with hyperthyroidism who received RAI therapy between 2008 and 2018 were included in the study. The data was acquired from the hospital's electronic medical record system. Following the RAI treatment, a cure was defined as the development of euthyroidism or hypothyroidism after a single fixed-dose without antithyroid medication within one year of RAI therapy. In addition, a simple logistics regression model was used to identify the prognostic factors that may lead to better outcomes. Results A total of 112 patients diagnosed with hyperthyroidism with a mean age of 47 ± 14 were included in this study. The majority of the patients were female, 79 (70.5%). Within one year of RAI therapy, 84 (75%) patients achieved a cure that is either hypothyroid or euthyroid status. RAI dose was higher in responsive patients (18.50 ± 4.10 millicurie [mCi] versus 16.50 ± 4.10 mCi) than in non-responsive patients. The mean RAI doses were 16.05 ± 2.99 mCi in GD, 19.81 ± 4.40 mCi in TMNG, and 20.50 ± 3.30 mCi in TA, with a statistically significant p-value of 0.001. In the univariable logistic regression model, RAI dose was a significant prognostic factor of the responsive group (OR: 1.15, CI [1.01-1.31], p-value 0.03). Conclusion Our data presented that RAI therapy is effective for primary hyperthyroidism. We achieved remission with a single fixed-dose in the majority of patients. Most of our patients were cured within three months of RAI therapy. In addition, the RAI dose was higher in the responsive group as compared to the non-responsive group.