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.
Keywords
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