Analysis of risk factors of rapid thyroidal radioiodine-131 turnover in Graves' disease patients.

Rapid iodine-131(I) turnover in the thyroid gland is an important feature of Graves' disease (GD) and also a strong predictor of radioiodine therapy failure. The aim of this study was to explore the predictors of rapid I turnover. The clinical data on 2543 patients were retrospectively reviewed. Patients were divided into 2 groups depending on present or absent with rapid I turnover defined as a 4-hour to 24-hour I uptake ratio of ≥1. Overall, 590 cases (23.2%) had a rapid I turnover. In the univariate analysis, gender, age, FT/FT concentration, disease duration, with or without antithyroid drugs (ATD), time of ATD, thyroid weight and thyroid textures displayed significant differences. Cutoff values of age, FT and thyroid weight to predict rapid I turnover were 38 years, 35 pmol/l and 56 g by receiver operating characteristic curves. Binary logistic regression analysis further revealed higher probability of rapid I turnover in patients with thyroid weight ≥56 g (odds ratio [OR]:3.7, 95% confidence interval [CI]: 3.032-4.559), age <38 years (OR:2.3, 95%CI: 1.906-2.856), FT concentration ≥35 pmol/l (OR:7.6, 95%CI: 5.857-8.563) and females (OR:2.2, 95%CI: 1.757-2.791). In conclusion, larger goiters, younger age, higher FT concentration and females are independently associated with rapid I turnover in GD patients.