Comparative evaluation of two different dosage calculation protocols of iodine-131 in the treatment of hyperthyroidism

Abstract

Objective: To compare the effectiveness of radioiodine therapy with estimated dose and calculated dose in hyperthyroid patients. Material and Method: A prospective randomized study in 144 hyperthyroid patients referred for 131I treatment was performed between June and December 2007. The patients were divided into two groups according to the I dose administered, estimated group using dose based on gland size and calculated group using dose based on both gland size and 24-hour 131I uptake. Outcome assessment was done at 12 months post-treatment. Results: Eleven of 144 patients were excluded due to loss to follow-up and five became euthyroid before 131I treatment. Fifty-six of 128 patients (45.3%) experienced persistent/recurrent hyperthyroidism, 26 (20.3%) developed hypothyroidism, and 44 (34.4%) were euthyroid. Outcome was unrelated to the methods of I-131 dosing. Only gender and goiter size were found to be correlated with the clinical outcomes. Conclusion: An estimated I-131 dosing method using gland size determined by palpation is as effective as calculated method using 131I uptake. This method is more cost effective and brings greater patient convenience.