Revisões, Atualizações e Artigos Originais February 01, 2004 February 01, 2004

Amiodarone and the thyroid

DOI: 10.1590/S0004-27302004000100020

Amiodarone is an iodine-rich drug widely used for the management of cardiac arrhythmias. During long-term amiodarone therapy drug toxicity may occur and a substantial proportion of amiodarone-treated patients develop either hypothyroidism or thyrotoxicosis. Several mechanisms are involved in amiodarone-induced thyroid dysfunction: defective thyroid auto-regulatory mechanism in presence of excessive iodine offer, immunological factors and cytotoxicity. Approximately 50% of patients taking amiodarone present abnormal thyroid function. Therefore, for adequate clinical follow up of these patients, it is critical a careful monitoring of thyroid hormones and TSH, before and during treatment.