Enlargement of the thyroid gland , causing a prominent swelling at the throat.
The thyroid can grow to 50 times its normal weight, interfere with breathing and swallowing, and cause a choking feeling. Simple (endemic) goitre, the most common, is due to low iodine intake. It and related conditions result from various defects in thyroid hormone synthesis (hypothyroidism). Advanced cases are treated with thyroid hormone or surgical removal of the thyroid if it obstructs breathing. The cause of sporadic goitre, which occurs in areas where iodine intake is more than adequate, remains a mystery. An enlarged thyroid may have normally functioning tissue or may produce too much hormone (hyperthyroidism). See also Graves disease .