Thyroid gland hormone

Thyroid extract/thyroxine Hormone Thyroid gland... 

Thyroid compounds Thyroid counter Thyroid gland Thyroid hormone... 

Factors controlling calcium homeostasis are calcitonin, parathyroid hormone(PTH), and a vitamin D metabolite. Calcitonin, a polypeptide of 32 amino acid residues, mol wt - SGOO, is synthesized by the thyroid gland. Release is stimulated by small increases in blood Ca " concentration. The sites of action of calcitonin are the bones and kidneys. Calcitonin increases bone calcification, thereby inhibiting resorption. In the kidney, it inhibits Ca " reabsorption and increases Ca " excretion in urine. Calcitonin operates via a cyclic adenosine monophosphate (cAMP) mechanism. 

The main role of the human thyroid gland is production of thyroid hormones (iodinated amino acids), essential for adequate growth, development, and energy metaboHsm (1 6). Thyroid underfunction is an occurrence that can be treated successfully with thyroid preparations. In addition, the thyroid secretes calcitonin (also known as thyrocalcitonin), a polypeptide that lowers excessively high calcium blood levels. Thyroid hyperfunction, another important clinical entity, can be corrected by treatment with a variety of substances known as antithyroid dmgs. 

Several years ago, it was discovered that the thyroid gland was also the source of a hypocalcemic hormone having effects in general opposition to those of the parathyroid hormone. This hormone is produced in mammals by the parafollicular C-ceUs and in other vertebrates by the ultimobrachial bodies (45). Originally called thyrocalcitonin, it is now referred to as calcitonin (CT). 

Three hormones regulate turnover of calcium in the body (22). 1,25-Dihydroxycholecalciferol is a steroid derivative made by the combined action of the skin, Hver, and kidneys, or furnished by dietary factors with vitamin D activity. The apparent action of this compound is to promote the transcription of genes for proteins that faciUtate transport of calcium and phosphate ions through the plasma membrane. Parathormone (PTH) is a polypeptide hormone secreted by the parathyroid gland, in response to a fall in extracellular Ca(Il). It acts on bones and kidneys in concert with 1,25-dihydroxycholecalciferol to stimulate resorption of bone and reabsorption of calcium from the glomerular filtrate. Calcitonin, the third hormone, is a polypeptide secreted by the thyroid gland in response to a rise in blood Ca(Il) concentration. Its production leads to an increase in bone deposition, increased loss of calcium and phosphate in the urine, and inhibition of the synthesis of 1,25-dihydroxycholecalciferol. 

Hyperthyroidism, that is, the overproduction of thyroid hormones, is usually treated by surgical removal of the thyroid gland. Before such a procedure is undertaken, the hyperthyroidism is usually first brought under control by treatment with so-called antithyroid agents. 

Thyroid gland. An endocrine gland that secretes thyroxin and triiodothyronine, hormones that modulate the rate of cellular metabolism. 

In addition to the twenty amino acids commonly found in proteins, two others—selenocysteine and pyrrolysine—are found in some organisms, and more than 700 nonprotein amino acids are also found in nature. y-Amino-butyric acid (GABA), for instance, is found in the brain and acts as a neurotransmitter homocysteine is found in blood and is linked to coronary heart disease and thyroxine is found in the thyroid gland, where it acts as a hormone. 

Antithyroid dru inhibit the manufacture of thyroid hormones. They do not affect existing tiiyroid hormones tiiat are circulating in die blood or stored in die thyroid gland. For tiiis reason, therapeutic effects of the antithyroid drugs may not be observed for 3 to 4 weeks. Antithyroid drugs are listed in the Summary Drug Table Thyroid and Antithyroid Drugs. 

Strong iodide solutions act by decreasing the vascularity of the thyroid gland by rapidly inhibiting the release of the thyroid hormones. Radioactive iodine is distributed within the cellular fluid and excreted. The radioactive isotope accumulates in the cells of the tiiyroid gland, where destruction of tiiyroid cells occurs without damaging other cells throughout the body. 

C03-0144. The thyroid gland produces hormones that help regulate body temperature, metabolic rate, reproduction, the synthesis of red blod cells, and more. Iodine must be present in the diet for these thyroid hormones to be produced. Iodine deficiency leads to sluggishness and weight gain, and can cause severe problems in the development of a fetus. One thyroid hormone is thyroxine, whose chemical formula is... 

Lithium is concentrated in the thyroid gland and can impair thyroid hormone synthesis. Although goiter is uncommon, as many as 30% of patients develop at least transiently elevated thyroid-stimulating hormone values. Lithium-induced hypothyroidism is not usually an indication to discontinue the drug. Patients can be supplemented with levothyroxine if continuation of lithium is desired.30... 

Despite the availability of a wide array of thyroid hormone products, it is clear that synthetic levothyroxine (LT4) is the treatment of choice for almost all patients with hypothyroidism. LT4 mimics the normal physiology of the thyroid gland, which secretes mostly T4 as a prohormone. As needed, based on metabolic demands, peripheral tissues convert thyroxine (T4)... 

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