Iodine

Iodine is a critically important component of thyroid hormones. There are four iodine atoms per molecule of l-thyroxine, and three per molecule of l-triiodothyronine. The highest content of iodine in food is found in fish, with lesser amounts occurring in eggs, milk, and meat. Fruits and vegetables contain little iodine. Without iodine supplementation, people in most inland areas of the world, particularly mountainous regions, have iodine deficiency. This was the case in the United States before iodinization of salt. When iodine deficiency prevails, goiter and hypothyroidism commonly occur, along with congenital cretinism—all preventable diseases. Iodine excess, usually a result of diagnostic medical procedures or medications, can produce either hypothyroidism or hyperthyroidism in patients with different types of underlying thyroid disease.

MARTIN I. SURKS

(SEE ALSO: Goiter; Hyperthyroidism; Hypothyroidism; Thyroid Disorders)

BIBLIOGRAPHY

Medeiros-Netos, G. (1999). "Congenital and Iodine-Deficiency Goiters." In Atlas of Clinical Endocrinology, Vol. 1: Thyroid Diseases, ed. M. I. Surks. Philadelphia, PA: Current Medicine.