Amiodarone-induced thyrotoxicosis: four cases and a review of the literature.

Hyperthyroidism is a rare side effect of amiodarone treatment. Four patients with this untoward effect are described One patient with mild hyperthyroidism before treatment with amiodarone, developed prolonged severe resistant thyrotoxicosis 6 months after initiation of this drug. A second patient with Wolf-Parkinson-White syndrome and paroxysmal atrial fibrillation was successfully stabilized with amiodarone for 18 months. However, the arrhythmia recurred and the thyroid function tests were found to be elevated. In 2 other patients only slight elevation of the thyroid function tests were found without clinical manifestations 4 months after treatment with amiodarone had been initiated.