The thyroid gland is a butterfly-shaped gland located at the neck.  It is responsible for interacting with another endocrine gland of the body which is the pituitary gland and the hypothalamus.  The thyroid hormone controls the hypothalamus to produce thyrotropin releasing hormone which signals the pituitary gland to produce thyroid stimulating hormone.  The thyroid stimulating hormone signals the thyroid gland to produce thyroxine which controls the hypothalamus in return to control the amount of thyrotropin releasing hormone.

Problems may occur when the body does not have enough iodine in the form of iodide ions to produce thyroxine.  This leads to a reaction of producing too much thyrotropin releasing hormone which produces thyroid stimulating hormone.  Because the other mechanisms is telling the thyroid gland to produce thyroxine but the thyroid gland is unable to because of the iodine deficiency, the person may develop goiter, which is an enlargement of the thyroid gland.  Salt that is fortified with iodine or eating iodine rich-foods such as dried fish is a good way to ensure that the body is able to produce all the thyroxine that it can.