Amiodarone and the thyroid

doi:10.1016/j.amjmed.2004.11.028

The American Journal of Medicine

Volume 118, Issue 7, July 2005, Pages 706-714

https://doi.org/10.1016/j.amjmed.2004.11.028 Get rights and content

Abstract

Among the drugs affecting the thyroid gland, no drug has puzzled, and at the same time fascinated, endocrinologists more than amiodarone. Amiodarone is a potent class III anti-arrhythmic drug that also possesses beta-blocking properties. It is very rich in iodine, with a 100-mg tablet containing an amount of iodine that is 250 times the recommended daily iodine requirement. Amiodarone produces characteristic alterations in thyroid function tests in euthyroid patients. Understanding these alterations is crucial in avoiding unnecessary investigations and treatment. Amiodarone-induced thyroid dysfunction occurs because of both its iodine content and the direct toxic effects of the compound on thyroid parenchyma. Amiodarone-induced hyperthyroidism is more common in iodine-deficient regions of the world, whereas amiodarone-induced hypothyroidism is usually seen in iodine-sufficient areas. In contrast to amiodarone-induced hypothyroidism, amiodarone-induced thyrotoxicosis is a difficult condition to diagnose and treat. In this review, we discuss the alterations in thyroid function tests seen in euthyroid subjects, the epidemiology and mechanism of amiodarone-induced thyroid dysfunction, treatment options available, and the consequences of amiodarone use in pregnancy and lactation; and finally, we propose a follow-up strategy in patients taking amiodarone.

Section snippets

Methods

All English language articles related to amiodarone and the thyroid were searched in MEDLINE from 1966 to 2004. The key words included amiodarone AND thyroid, amiodarone AND hyperthyroidism, amiodarone AND hypothyroidism, amiodarone AND pregnancy, amiodarone AND lactation, amiodarone-induced hypothyroidism AND diagnosis, amiodarone-induced hypothyroidism AND treatment, amiodarone-induced hyperthyroidism AND diagnosis, amiodarone-induced hyperthyroidism AND treatment. The selection criteria

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