Iodine is a key component of the hormone thyroxin, produced by the thyroid gland. Thyroxin regulates the level of metabolism and is essential for normal development of the fetus. Iodine is absorbed from the digestive tract and carried by serum proteins to the thyroid gland where it is stored in thyroxin and its precursors. An iodine deficiency produces compensatory hypertrophy of the thyroid gland, resulting in a goiter. Cretinism is a consequence of severe iodine deficiency in early pregnancy.
Cretins are feeble-minded dwarfs with characteristic faces and gait.
Mild to moderate maternal deficiency during pregnancy causes lesser degrees of neurological damage, particularly poorer cognitive performance and hearing impairment. Initially, goiters are soft and diffuse but become fibrotic in older individuals. Nodular goiters are a common result of maternal iodine deficiency. Thyroxine deficiency in adults results in hypothyroidism characterized by a low metabolic rate. Potassium iodate is used more frequently as it has the advantage of being stable in crude moist salt even under unfavorable conditions.