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A goiter is an enlargement of the thyroid gland that can lead to a prominent swelling in the front of the neck—sometimes nearly doubling its size. While the thyroid normally weighs 0.5 to 0.9 oz (15 to 25 g), goitrous thyroid glands can grow to more than 2 lb (1,000 g) and may interfere with breathing and swallowing and cause a choking feeling. A goiter can be caused by underproduction or overproduction of hormones, but endemic goiter, the most common type, results from a deficiency of what? Discuss
Source: The Free Dictionary