TopicThyroid Disease in Women - Causes, Symptoms and Treatments
Endemic goiters develop when the lack of iodine prevents the Thyroid Factor Review formation of sufficient quantities of the thyroid hormones thyroxine and triiodothyronine. Because of the low concentrations of thyroid hormone, there is nothing that could inhibit the production of thyroid-stimulating hormone or TSH by the pituitary gland, which would result in the anterior pituitary gland secreting increased amounts of the hormone targeting the thyroid gland.
The increased levels of TSH stimulate the thyroid gland to produce increased amounts of thyroglobulin. However, without iodine to bind to the tyrosine residues in the tyroglobulin molecule, there is still no production of hormones. This causes the thyroid gland to increase in size, sometimes to as large as 10 to 20 times its normal size.
Similarly enlarged thyroid glands filled with colloid may also happen to people who do not have an iodine deficiency, unlike patients with endemic goiter. These people may have normal levels of thyroid hormone secretion but more often than not, the secretion of thyroid hormone is depressed like that of endemic goiter.
The exact cause for the enlargement of the thyroids of patients with iodiopathic nontoxic colloid goiter is not known. However, most of these patients do show signs of mild thyroiditis, which led to the suggestion that thyroiditis might lead to slightly lower concentrations of the hormone, which in turn could cause increase in TSH secretion and progressive growth of unaffected portions of the gland.