The role of antithyroglobulin, antiperoxidase and anti-TSH receptor autoantibodies in amiodarone-induced thyrotoxicosis and amiodarone-induced hypothyroidism (A two-center study).

OBJECTIVE: It has been reported that patients experiencing side effects of amiodarone (AM) therapy, such as amiodarone-induced thyrotoxocosis (AIT) or amiodarone-induced hypothyroidism (AIH), have changes in serum concentrations of anti-TSH receptor (TSHR), antithyroglobulin (Tg), and antiperoxidase (TPO) autoantibodies (Abs). The purpose of our study was to identify and analyze the changes in levels of listed antibodies in patients with several thyroid disorders.

METHODS: 280 patients from two centers in Poland were included. Titers of TSHR-Abs, TPO-Abs and Tg-Abs were analyzed retrospectively in the following groups of patients: A - euthyroid patients with a history of hyperthyroidism prior to re-administration of AM; B - patients with AIT who discontinued the AM therapy; C - patients with AIT chronically treated with AM; D - hypothyroid patients.

RESULTS: Serum Tg-Abs were not elevated in any of the studied groups. However, there were significant differences between A and B and also D and other groups (p<0.05). TPO-Abs titers were not elevated in most cases, there were no significant differences between groups. The serum titers of TSHR-Abs were not elevated in any group. We found statistically significant differences between B and D, C and other groups (p<0.05).

CONCLUSIONS: Regardless of the statistically significant differences observed for Tg-Abs and TSHR-Abs levels, this observation have a limited clinical applicability. In almost all cases we observed normal to slightly increased titers of TPO-Abs, Tg-Abs, TSHR-Abs. Discontinuation or continuation of AM therapy had no influence on autoantibody titers. Furthermore, we found it impossible to differentiate between the type I and II of AIT based on autoantibody titers.