Thyroid volume is the key predictor of hyperthyroidism remission after RAIT in pediatric patients

Abstract

Abstract Graves' disease (GD) is the leading cause of hyperthyroidism in pediatric patients. Radioiodine therapy (RAIT) is widely used to treat GD, however, the predictors of efficacy of RAIT in childhood and adolescence are still not completely clear. Our purpose was to determine the most significant predictors of efficacy of RAIT in pediatric patients. The study enrolled 144 patients (124 females; 20 males) aged 8 to <18 years old who received the primary dosimetry-guided RAIT for GD. The parameters analyzed included gender, age, thyroid volume according to ultrasound examination before and 12 months after treatment, thyroid stimulating hormone (TSH), free triiodothyronine (FT3) free thyroxine (FT4), TSH receptor antibodies (TRAB) levels at baseline and twelve months after RAIT, 10-20-Min 99mTc thyroid uptake (%), maximum thyroid 131I uptake (%), specific 131I uptake (MBq/g) and therapeutic 131I activity (MBq). Fisher's exact test, Mann-Whitney U-test, Wilcoxon signed–rank test, ROC–analysis and Youden index were used for statistical analysis. Six months after RAIT, hypothyroidism was achieved in 119 (82.6%) patients, euthyroid state was achieved in 6 (4.2%), and hyperthyroidism persisted in 19 (13.2%). Thyroid volume decreased from 17.6 [14.6; 24.1] to 9.25 [7.62; 13.34] mL 12 months after the treatment (p<0.001). The main predictor that showed a statistically significant difference between the groups of patients who achieved and did not achieve remission of GD hyperthyroidism after RAIT was the initial thyroid volume. Using Youden index the optimal cut-off point of the initial thyroid volume in 45.4 ml was determined.Conclusion: The efficacy of the dosimetry-guided RAIT in pediatric patients with GD was 82.6% after 12 months, and one of the major predictors of RAIT success was an initial smaller thyroid volume.