[Amiodarone-induced thyrotoxicosis: case report and review of the literature]

Abstract

We report a case of amiodarone-induced thyrotoxicosis, and a broad review of the literature. Amiodarone is a drug widely used in cardiovascular medicine. Since it is iodine-rich, it may cause changes in thyroid function tests in some patients under chronic treatment. In 14-18% of amiodarone-treated patients, there is overt thyroid dysfunction (hypothyroidism or thyrotoxicosis). We here describe thyrotoxicosis, which can be distinguished in two subtypes differing in pathogenesis and treatment. Type I is primarily related to an excess of iodine-induced thyroid hormone synthesis in an abnormal thyroid gland, and the main medical treatment consists of the simultaneous administration of thionamides and potassium perchlorate. Type II is due to amiodarone-related destructive thyroiditis and glucocorticoids are therapy of choice. Mixed forms frequently exist. Due to the low thyroidal iodine uptake, radioiodine therapy is usually not efficacious. Surgical treatment can be performed in cases resistant to medical therapy.