Severe iodine deficiency is defined as a goiter prevalence greater than 30 % and/or a median urinary iodine concentration (UIC) of less than 20 µg/L in a given population or defined geographical area. The adaptive processes of the thyroid gland may be unable to compensate for this degree of iodine deficiency, leading to manifestations which include endemic goiter, hypothyroidism, obstetric complications, intellectual impairment, and cretinism. However, the manifestations of severe iodine deficiency have decreased globally primarily due to widespread coverage with adequately iodized salt.