Adequate iodine nutrition may be achieved from dietary intake of iodine-fortified foods, including iodized salt, or ingestion of iodine-containing multivitamins or supplements. Inadequate iodine has been associated with hypothyroidism, as well as adverse obstetric and developmental and cognitive outcomes among offspring born to women with insufficient iodine during pregnancy. Requirements for iodine intake are increased during pregnancy and lactation in order to provide adequate iodine nutrition for the developing fetus and breastfed infant.
However, excess iodine exposure also carries the risk of iodine-induced thyroid dysfunction, particularly among individuals with pre-existing thyroid disease, the elderly, and in the fetus and neonate, in whom thyroid gland development is still immature. Sources of excess iodine include use of iodine-containing medications, topical iodine antiseptics, and radiographic iodinated contrast media. Biochemical hypothyroidism or hyperthyroidism resulting from an acute iodine load may be transient or permanent, either subclinical or overt, and the source of the excess iodine might not be readily apparent. With the exception of specific medical indications supporting the use of supraphysiologic iodine, chronic excessive iodine ingestion and/or exposure should be avoided.