Goitre, enlargement of the thyroid gland, resulting in a prominent swelling in the front of the neck. The normal human thyroid gland weighs 10 to 20 grams (about 0.3 to 0.6 ounce), and some goitrous thyroid glands weigh as much as 1,000 grams (more than 2 pounds).
The entire thyroid gland may be enlarged, or there may be one or more large thyroid nodules. The function of the thyroid gland may be decreased, normal, or increased. A very large goitre may cause sensations of choking and can cause difficulty in breathing and swallowing.
The most common type of goitre is endemic goitre, caused by iodine deficiency. Iodine is an essential nutrient that is required for the production of thyroid hormone. When iodine intake is low, thyroid hormone production is low, and in response the pituitary gland secretes greater quantities of the hormone thyrotropin (thyroid-stimulating hormone, TSH) in an attempt to restore thyroid hormone production to normal.
This excess thyrotropin stimulates not only thyroid hormone production but also thyroid growth. Endemic goitre is more common among girls than boys and among women than men.
