Parathyrin Parathyroid hormone

Parathyrin (parathyroid hormone, parathormone, PTH) is secreted by the parathyroid glands. A peptide of 84 amino acids, it has two precursors during its biosynthesis, a... 

Armitage EK. Parathyrin (parathyroid hormone) metabolism and methods of assay. Clin Chem 1986 32 418-24. 

Potts JT, Jr., Bringhurst FR, Gardella TJ, et al. Parathyroid hormone Physiology, chemistry, biosynthesis, secretion, metabolism, and mode of action. In Degroot LJ (Ed.), Endocrinology. W.B. Saunders, Philadelphia, PA (1996) 920-965. Nussbaum SR, Zahradnik RJ, Lavigne JR, et al. Highly sensitive two-site immuno-radiometric assay of parathyrin and its clinical utility in evaluation patients with hypercalcemia. Clin. Chem. (1987) 33 1364-1367. 

Parathyroid hormone (PTH), parathormone, parathyrin, SVSEIQLMHN LGKHLNS MER VEWLRKKLQD VHNFVALGAP ... 

Parathormone, parathyrin a hormone produced by the parathyroid gland, which influences the metabolism of calcium and phosphate. It is a single chain proteohormone with 84 amino acid residues of known primary structure [R.T. Sauer etal. Biochemistry 13 (1974), 1994-1999]. M, 9,402 (porcine). P. influences the cells that degrade bone (osteoclasts) by activation of membrane-bound adenylate cyelase and by increasing the entry of Ca into these cells. The resulting mobilization of Ca causes an increase in blood ealcium. This is necessarily accompanied by the release of free phosphate which is excreted via the kidneys. Thus P. favors phosphate secretion in the distal part of the kidney tubule, and inhibits phosphate resorption in the proximal tubule. P. promotes calcium absorption by the intestine. The action of P. is therefore opposite to that of Calcitonin (see). P. is degraded by the liver, and some is excreted in the urine. Absence of P. leads to a decrease of blood calcium, accompanied by neuromuscular overexcitability (tetany). 

Boron is an essential element for plants. Whether it is essential for animals has not yet been unequivocally confirmed. Nevertheless, the biological effects of some compounds of boron are known. Boron has an impact on the effect of parathormone (also known as PTH or parathyrin), a hormone secreted by parathyroid glands, which increases blood levels of caldum by its mobilisation from bones (the antagonist of parathormone is calcitonin) and... 

Determinants of Calcium Metabolism.—In higher animals three factors operate (1) the parathyroid hormone, parathyrin (2) the D vitamins (3) sunlight or vUra-videt irradiation. Parathyrin given orally or intravenously raises the serum calcium until it reaches the level of pathological hypercalcmmia, characterised by vomiting, coma, and cardiac failure. Parathyroidectomy causes a fall in serum calcium until the lower level of 7 mg. Ca per 100 ml. is reached, when the syndrome of hypocalcsemia appears, characterised by tetany. 

The peptide hormone parathyrin (PTH), which is produced by the parathyroid gland, stimulates Ca "" resorption in the kidneys and at the same time inhibits the resorption of phosphate. In conjunction with the effects of this hormone in the bones and intestines (see p. 344), this leads to an increase in the plasma level of Ca and a reduction in the level of phosphate ions. 

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