Hypothyroidism and Goiter - Hypothyroidism Causes Enlargement of the Thyroid
By: aaron adish
Submitted: 2010-10-18 04:03:34 | Word Count: 714
Hypothyroidism and Goiter - Hypothyroidism Causes Enlargement of the Thyroid
Hypothyroidism, generally, has precisely the alternative effects as those of hyperthyroidism, although it could be caused by autoimmunity yet however a quite immunity that destroys the gland rather than stimulates it. Most of the patients first have autoimmune thyroiditis, an inflammation of the thyroid glands. This causes deterioration and eventually, fibrosis of the gland or the replacement of thyroid tissue with connective tissue. Fibrotic tissue is incapable of producing thyroid hormone and a deficiency in the hormone occurs. In most cases, an enlagement of the thyroid gland is observed.
Endemic Colloid Goiter
Around fifty milligrams of iodine are required each year for the traditional functioning of the thyroid gland and for production of sufficient amounts of thyroid hormone. In some areas of the world just like the Swiss Alps, the Andes, and also the Great Lakes regions of the United States of America, there are less than adequate quantities of iodine in the soil for the foodstuffs to contain this yearly requirement. In the days when iodized table salt was not yet accessible, folks from these areas developed extraordinarily large thyroid glands called endemic goiters.
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Endemic goiters develop when the lack of iodine prevents the formation of sufficient quantities of the thyroid hormones thyroxine and triiodothyronine. As a result of of the low concentrations of thyroid hormone, there is nothing that might 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 provide 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 extend in size, sometimes to as giant as ten to twenty times its traditional size.
Idiopathic Nontoxic Colloid Goiter
Similarly enlarged thyroid glands crammed with colloid might conjointly happen to folks who don't have an iodine deficiency, unlike patients with endemic goiter. These folks might have traditional levels of thyroid hormone secretion but a lot of 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. But, most of those patients do show signs of delicate thyroiditis, which led to the suggestion that thyroiditis might result in slightly lower concentrations of the hormone, which in turn might cause increase in TSH secretion and progressive growth of unaffected parts of the gland. This might explain why the thyroid glands of these patients are typically nodular, with some areas exhibiting growth whereas some are being destroyed by thyroiditis.
Some patients with colloid goiter exhibit abnormalities within the enzyme system that helps in the production of thyroid hormone. Some of these abnormalities are the following:
? There is a downside in the process of trapping iodine, in which the thyroid is unable to pump sufficient quantities of iodine into the thyroid cells.
? A deficiency in the peroxidase system, which renders the thyroid cells unable to oxidize iodides into the iodine state. If the iodides don't seem to be oxidized into the iodine state, they are unable to bind with the tyrosine within the thyroglobulin molecule, halting the complete method of thyroid hormone formation.
? A deficiency in the coupling of iodinated tyrosines therefore that thyroid hormones stay unformed.
? There's a downside in the deiodinase system, preventing the recovery of iodine from the iodinated tyrosines that aren't coupled to create thyroid hormones. This can eventually result in a deficiency in iodine.
? Some foods also contain goitrogenic substances, which can act like the anithyroid drug propylthiouracil, inducing hypothyroidism. This conjointly results in increased TSH stimulation of the thyroid gland, inflicting it to become enlarged. These goitrogenic substances might be found in some varieties of turnips and cabbages.
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