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The Thyroid gland is located in the front of the neck. It sits below the larynx, or voice box. It measures roughly two-inches and consists of two lobes. These two lobes sit on each side of the windpipe (one on the left, one on the right) and are connected by a bridge like tissue called the isthmus. It is made up of two types of cells: follicular cells and parafollicular cells, although most of the thyroid tissue is made of the follicular cells. These cells secrete iodine-containing hormones call thyroxin (T4) and triiodothyronine (T3). The reason for this is because the thyroid needs iodine to produce the hormones. The parafollicular cells secrete the hormone calcitonin. The thyroid plays an important role in regulating the body’s metabolism and calcium balance. The hormones stimulate every tissue to produce proteins and increase the amount of oxygen used by the cells. The levels of the hormones secreted by the thyroid are controlled by the pituitary glands thyroid-stimulating hormone, which in turn is controlled by the hypothalamus.
T4 is synthesized by the collicular cells from the tyrosine and on the tyrosine residues of the protein called thyroglobulin (Tg). The hydrogen peroxide generated by the enzyme thyroid peroxidase captures iodine using an “iodine trap”. When stimulated by the TSH (thyroid- stimulating hormone), the follicular cells reabsorb thyroglobulin and cleave the iodinated tyrosine from Tg lysosomes, forming T4 and T3. The major target of the thyroid hormones T3 and T4 are the cells of the developing brain. The thyroid hormones play a crucial role in brain maturation during fetal development. The production of T4 and T3 are regulated by the TSH, which is released by the anterior pituitary. When T4 levels are too ...

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...genital thyroid abnormalities, autoimmune disorders, iodine deficiency, the removal of the thyroid following surgery to treat severe hyperthyroidism and thyroid cancer. Symptoms include but are not limited to; abnormal weight gain, tiredness, baldness, cold intolerance, and bradycardia. This disorder is treated with hormone replacement therapy, such as levothyroxine.
There is also a disease called thyroiditis. There are two types: Hashimoto’s thyroid and postpartum, thyroiditis. Hashimoto’s thyroiditis is an autoimmune disorder whereby the body’s own immune system reacts with the thyroid tissues in an attempt to destroy it. At the beginning, the gland may be overactive as the gland damaged resulting in too little thyroid hormone production of hypothyroidism. Some patients may experience “swings” in hormone levels that can progress rapidly from hyper to hypo thyroid.

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