Successful treatment of amiodarone-induced thyrotoxicosis

Background-Amiodarone-induced thyrotoxicosis (AIT) is a difficult management problem about which there are little published data. We examined whether continuing amiodarone or differentiating AIT into 2 subtypes affected outcome. Methods and Results-The type and duration of antithyroid treatment and response were recorded in a consecutive series of 28 cases. Comparisons were made between those in whom amiodarone either was continued or stopped and between those with either possible type I or type 2 AIT. Of the 28 cases, 5 had spontaneous resolution of AIT; 23 received carbimazole (CBZ) alone as first-line therapy. Eleven achieved long-term euthyroidism off CBZ or on a maintenance dose. Five became hypothyroid and required long-term thyroxine. Five relapsed after stopping CBZ treatment and were rendered euthyroid with either long-term CBZ (n=3) or radioiodine (n=2). Four were intolerant of CBZ and received propylthiouracil (PTU). with good effect in 3. One was resistant to thionamide alone (CBZ then PTU) and responded to adjunctive steroids. No difference in presentation or outcome was noted between those in whom amiodarone was continued or stopped or between possible type I or type 2 AIT. Conclusions-Continuing amiodarone has no adverse influence on response to treatment of AIT. First-line therapy with a thionamide alone is appropriate in iodine-replete areas, thus avoiding potential complications of other drugs. Differentiating between 2 possible types of AIT does not influence management or outcome.