131I therapy for 345 patients with refractory severe hyperthyroidism: Without antithyroid drug pretreatment

The aim of this study is to evaluate the safety and long-term results of (131)I therapy alone for patients with refractory severe hyperthyroidism without antithyroid drug pretreatment. From January 2002 to December 2012, 408 patients with refractory severe hyperthyroidism were treated with (131)I alone. Among them, 345 were followed up for 1 to 10 years for physical examination, thyroid function, and thyroid ultrasound. Complete Blood Count (CBC) liver function, electrocardiogram, echocardiogram, and Emission Computed Tomography (ECT) thyroid imaging were performed as indicated. The 345 patients had concomitant conditions including thyrotoxic heart disease, severe liver dysfunction, enlarged thyroid weighing 80 to 400 g, severe cytopenia, and vasculitis. One to two weeks prior to (131)I therapy, all patients were given low-iodine diet. The dose of (131)I therapy was 2.59 to 6.66 MBq (70 to180 µCi) per gram of thyroid with an average of 3.83 ± 0.6 MBq (103.6 ± 16.4 µCi); and the total (131)I activity administrated for the individuals was 111 to 3507.6 MBq (3.0 to 94.8 mCi, mean 444 ± 336.7 MBq (12.0 ± 9.1 mCi)). Out of the 408 patients, 283 were cured, 15 with complete remission, and 47 with incomplete remission. No treatment failure or significant clinical worsening was noted in these patients. Our data indicated that (131)I therapy alone for patients with refractory severe hyperthyroidism without antithyroid drug pretreatment is safe and effective.