Glucocorticoids Are Preferable to Thionamides as First-Line Treatment for Amiodarone-Induced Thyrotoxicosis due to Destructive Thyroiditis: A Matched Retrospective Cohort Study

Abstract

Type 2 amiodarone-induced thyrotoxicosis (AIT) is a destructive thyroiditis usually responsive to glucocorticoids; however, recent surveys showed that many expert thyroidologists worldwide use thionamides for type 2 AIT patients. The objective of the study was to compare the effectiveness of methimazole (MMI) or prednisone (GLU) in type 2 AIT patients who had a short cure time according to a published predictive model. This was a matched retrospective cohort study. The study was conducted at a university center. Forty-two untreated type 2 AIT patients with a predicted cure time < or = 40 d were divided into two groups (MMI and GLU groups). After matching for the predicted cure time, patients in the GLU group were selected in a 1:1 ratio to patients in the MMI group. Patients were treated with GLU or MMI for 40 d. Patients still thyrotoxic after 40 d continued glucocorticoids if in the GLU group or were switched to prednisone (MMI-GLU group) if in the MMI group. Time and rate of cure (healing) at 40 d were measured. Patients still thyrotoxic after 40 d were 23.8 +/- 9.3% in the GLU group and 85.7 +/- 7.6% in the MMI group (P = 0.000). The GLU and MMI-GLU groups did not significantly differ in the nonhealing rate at 40 d (P = 0.730). When patients in the MMI group were treated with glucocorticoids, 94.1% patients achieved euthyroidism within 40 d. However, the global median cure time (MMI period + prednisone period) was longer (60 d, 95% confidence interval 53.5-66.5 d) in the MMI-GLU group than the GLU group (21 d, 95% confidence interval 15.1-26.9 d). Glucocorticoids are the first-line treatment in type 2 AIT, whereas thionamides play no role in this destructive thyroiditis.