ABSTRACT
Iodine deficiency used to be highly prevalent in many parts of the world until salt iodization programs and other prevention strategies were implemented and scaled up, beginning in the 1980s in most countries. The only known function of iodine in the human body is in the synthesis of thyroid hormones, of which it is a key component. This makes iodine an essential nutrient. Circulating inorganic iodide is removed from the bloodstream for excretion by the kidney. Renal uptake occurs by passive diffusion and is relatively constant at 85" to 90" of daily iodine intake under conditions of sufficiency. Pregnancy induces several major changes in thyroid function and iodine metabolism. Maternal requirements are increased in pregnancy due to an increased iodine demand, and a higher than usual iodine clearance rate. Though infants are born with a functioning thyroid gland, they have only scant iodine stores at birth.
