ADVERSE-EFFECTS OF IODINE ON THE THYROID

Iodine excess usually is well tolerated by healthy individuals because of escape from its acute inhibitory effects on thyroid hormone synthe sis (acute Wolff-Chaikoff effect) and only subtle, physiological chang es in thyroid function occur. In contrast, excess iodine administratio n to patients with a wide variety of underlying thyroid disorders can induce hypothyroidism or hyperthyroidism, the latter more common in ar eas of iodine deficiency. Although less common, iodine-induced thyroid dysfunction also can occur in patients without recognized underlying thyroid disease. This review hopefully will provide the reader with an understanding of the pathophysiology of the effects of excess iodine on thyroid function and the diagnosis and therapy of these disorders, including a brief section on the adverse effects of the iodine-rich dr ug amiodarone.