Predictive factors of a worse response to radioactive Iodine-I131 treatment in hyperthyroidism: outcome analysis in 424 patients. A single centre experience

Purpose: Aim of our study was to search for variables associated with worse outcomes in patients treated with radioactive iodine (RAI) for hyperthyroidism by a dosimetric-based approach. Methods: Four hundred twenty-four patients with hyperthyroidism related to Toxic Multinodular Goiter (TMG; n = 213), Grave’s disease (GD; n = 150) and toxic adenoma (TA; n = 61) treated with RAI between 2000 and 2018 and with at least 12 months follow-up were retrospectively evaluated. Association between outcomes (response vs. no response) at 6 and 12 months and baseline TSH values, anti-thyroid drugs (ATD) duration and posology, RAI absorbed dose and dimensional reduction of target mass at ultrasound was evaluated by Mann–Whitney test. Risk factors for response vs. no-response were analysed by binary logistic regression model. Results: Overall response rate was 78.7 and 83% at 6 and 12 months, respectively. Both at 6 and 12 months higher TSH baseline values (p < 0.001), lower ATD duration (p = 0.004 ...