What causes a thyroid to become enlarged?

Mayo Clinic notes that a thyroid can become enlarged due to iodine deficiency, Graves’ disease, Hashimoto's disease, inflammation, pregnancy, multinodular goiter, thyroid cancer or solitary thyroid nodules. The American Thyroid Association reveals that thyroid enlargement or goiter can also occur when the thyroid produces a normal amount of hormone.

In Graves’ disease, there is overstimulation of the thyroid, which causes it to swell. Mayo Clinic explains that Hashimoto's disease causes low production of thyroid hormones, resulting in overstimulation from the pituitary gland and swelling of the thyroid. Multinodular goiter occurs when lumps form in the thyroid, making it too enlarge. Enlargement of one side of the thyroid indicates thyroid cancer. The American Thyroid Association notes that the diagnosis of goiter involves physical examination and blood tests to confirm underlying conditions.