Graves disease is the most common cause of hyperthyroidism in adults in the developed world. Treatment options include antithyroid drugs, radioactive iodine therapy (RAI) and surgery. RAI is safe and effective, and the preferred definitive therapy for most patients. The aim of this study was to assess outcomes of patients treated with RAI at the Princess Alexandra Hospital over ten years.
Between 2005 to 2015, data from 101 consecutive patients treated with RAI for a diagnosis of Graves disease were collected and retrospectively reviewed. Baseline TSH receptor antibody titre, technetium scan uptake, initial treatment, reason for definitive therapy, complications, and time to remission (euthyroidism or hypothyroidism after twelve months) were recorded.
Initial medical therapy was with Carbimazole in 93 patients (92%), Propylthiouracil (PTU) in 6 (6%) and 2 (2%) patients did not receive medical therapy prior to RAI. Following RAI, adequate outcome data was available for 92 patients. 73 (79.3%) patients achieved remission with a single dose of RAI. Of the 19 patients who did not achieve remission, 12 had a second dose and became hypothyroid. TSH receptor antibody titre at diagnosis was significantly lower in the group that achieved remission with the first dose compared with those who did not (P=0.0071). There was no difference in technetium uptake or RAI dose (mean dose: 495.7mBq). RAI was complicated by new onset of eye disease in 3 patients and 1 (of 11 with pre-existing eye disease) had worsening eye disease. A flare of hyperthyroidism following radioiodine was evident in 8 patients (8.6%).
Radioiodine is a safe and effective definitive therapy of Graves disease with few complications. The majority of patients achieve remission with a single dose. Those who require a second dose are more likely to have higher TSH receptor antibody titres at diagnosis.