Outcome of Radioiodine Treatment by Using 4-Hour l-131 Uptake Value for Dose Calculation in Graves’ Disease

Abstract

Objective: To evaluate outcome of radioiodine treatment by using 4-hour ¹³¹I uptake value for calculation therapeutic dose for patients with Graves’disease.

Materials and Methods: We studied 122 Graves’ disease patients with hyperthyroidism. The 4-hour ¹³¹I uptake was done in each patient. the 24- hour ¹³¹I uptake was estimated from the equation: predicted 24 hr ¹³¹I uptake = 36.7764 + 0.518 (4 hr ¹³¹I uptake). The RAI treatment dose was calculated using the formula based on estimated thyroid size and predicted 24-hour ¹³¹I uptake. We determined thyroid status of these patients at 1 year after the treatment.

Results: Ninety - five patients (77.9%) were euthyroidism or hypothyroidism at 1 year after treatment. and Twenty-seven patients (21.1%) had persistent hyperthyroidism. The patients who had persistent hyperthyroidism had larger thyroid gland (P < 0.001) and higher 4- hr ¹³¹I uptake value (P = 0.003). We found the outcome of treatment of our study were similar to the outcome of other studies that used other regimens in the treatment of Graves’ disease patients with ¹³¹I.

Conclusion: Radioiodine treatment (“*l) based on 4- hour ¹³¹I uptake is an effective treatment for patients with Graves’ disease. This approach is safe, simple and convenience for the patients.