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

Abstract

Rapid iodine-131(¹³¹I) 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 ¹³¹I turnover. The clinical data on 2543 patients were retrospectively reviewed. Patients were divided into 2 groups depending on present or absent with rapid ¹³¹I turnover defined as a 4-hour to 24-hour ¹³¹I uptake ratio of ≥1. Overall, 590 cases (23.2%) had a rapid ¹³¹I turnover. In the univariate analysis, gender, age, FT₃/FT₄ concentration, disease duration, with or without antithyroid drugs (ATD), time of ATD, thyroid weight and thyroid textures displayed significant differences. Cutoff values of age, FT₃ and thyroid weight to predict rapid ¹³¹I 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 ¹³¹I 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), FT₃ 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 FT₃ concentration and females are independently associated with rapid ¹³¹I turnover in GD patients.

Figure 1

ROC curves for age (A), thyroid weight (B) and FT₃ concentration (C) in predicting rapid thyroidal ¹³¹I turnover in GD patients.

Figure 2

A comparative analysis of the percent of rapid ¹³¹I turnover between the patients with age <38 years or ≥38years (A), thyroid weight <56 g or ≥56 g (B) and FT₃ concentration <35 pmol/l or ≥35 pmol/l (C).