The term nontoxic goiter refers to enlargement of the thyroid which is not associated with overproduction of thyroid hormone or malignancy. The thyroid can become very large so that it can easily be seen as a mass in the neck.

Less commonly, a thyroid will grow downward rather than up and out within the neck. When this happens, the thyroid will grow down the trachea into the chest.

Iodine deficiency disorders have recently been recognized as a potential target for eradication. Current estimates by World Health Organization indicate that about one billion people worldwide are at risk for iodine deficiency, but the severity of endemia differs strikingly from place to place