Endocrine Abstracts

Background: One of the main drawbacks of primary treatment of Graves’ disease (GD) with thionamide drugs (TD) is the high relapse rate estimated to be 50–60%. Fear about side effects, specially agranulocitosis and hepatic complications, is other drawback of this treatment option.

Objective: To evaluate the clinical and/or biochemical characteristics that might predict relapse in patients with GD treated with TD.

Design and patients: Clinical records of 264 hyperthyroid patients due to GD referred to our hospital outpatient clinic between 1998 and 2008 were reviewed. They were treated with a course of TD at least 6 months. TD were stopped when they had undetectable thyroid-stimulating antibodies (TSAbs) and/or were euthyroid. At the end of the treatment, patients were followed-up for at least 1 year.

Results: 214 patients were females. Mean age at diagnosis was 40.38±13.68 years (14-80). Mean treatment duration was 19.9±6.2 months (6–51). Only seven patients were treated with propylthiouracil. Mean time of follow-up after stopping TD was 30.5 months. Relapsing Graves’ hyperthyroidism was observed in 154 (58.3%) patients. In univariate analysis, relapse was associated with younger age (P<0.05), higher level at diagnosis of free thyroxine (T4) (P<0.05) and free triiodothyronine (T3) (P<0.001) and higher TSAbs levels at the end of the TD course (P<0.0001). By multivariate analysis only initial free T4 and free T3 levels and TSAbs level at withdrawal were indepently associated with relapse. The percentage of relapsing patients at 12, 24 and 60 months after discontinuation of TD was 60.1%, 82.5% and 94.4%. Only 36 patients (13.6%) have maintained euthyroidism after 60 months of TD withdrawal. No major adverse reaction was observed. Minor adverse effects occurred in 11 patients (4.2%).

Conclusions: Hyperthyroidism relapse in patients with GD treated with TD in our study group was associated with analytical features of severe hyperthyroidism at diagnosis and higher TSAbs levels before stopping TD. Moreover, a low percentage of patients were in remission after 60 months of TD discontinuation. This may help early consideration of alternative therapy for those patients who have aggressive disease at diagnosis and/or who are TSAb-positive before TD withdrawal. In our study, TD showed to be safe, with a low rate of minor adverse effects.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector