甲状腺疾患と治療のジャーナル
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概要

Quantitative Radioiodine Treatment of Graves' Hyperthyroidism Using Different Intended Activities and the Same Weighting Factor

Shiwei Sheng, Yang Wang, Maomei Ruan, Tao Ying and Libo Chen

Context: There is little consensus on the most appropriate dose regimen for radioiodine treatment (RIT) of Graves’ hyperthyroidism (GH), and quantitative studies on the role of the efficacy-affecting parameters are lacking.
Objective: This prospective study was designed to evaluate the feasibility of quantitative RIT of GH using a modified formula, which took into account eight parameters associated with the outcome.
Design: A 1-year follow-up study of 205 GH patients was performed.
The administered activity of 131I was established using a formula,
Activity MBq = [(gland weight (g) ×in tended activity) (MBq/g) /Max uptake] (% )× (1 + X/30) in which the X represented the sum of the parameters, and the administered activity increased or decreased by 1/30 when each of the parameters was present or absent. The subjects were randomized into two groups according to the intended activity.
Results: No significant differences at baseline were noted between the two groups. The mean administered activity of 131I in 3.7 MBq/g group was significantly lower than that in 5.55 MBq/g group. One year after therapy, 77.6% patients were treated successfully, with 76.3% in the 3.7 MBq/g group (58.8% achieved euthyroidism, 17.5% became hypothyroid) and 78.7% in the 5.55 MBq/g group (38.9% achieved euthyroidism, 39.8% became hypothyroid). Hypothyroidism occurred earlier in the 5.55 MBq/g group with rates significantly higher than those in the 3.7 MBq/g group.
Conclusions: The modified formula seems feasible in the RIT of GH, which takes into account the quantification of efficacy-affecting parameters. The intended activity of 5.55 MBq/g may result in a higher rate of hypothyroidism and an earlier cure of hyperthyroidism than the activity of 3.7 MBq/g, which appears to be more favorable for maintaining euthyroidism.