| Mechanism |
Cinacalcet is a basic single-chain peptide hormone secreted by the parathyroid chief cells , called PTH, it is a blend of 84 amino acids,it has an effect of elevating serum calcium and lowing phosphorus, regulating calcium and phosphorus metabolism balance of vertebrate body . In parathyroid cells,the first main precursor of PTH is synthesized at first, it is called Prepro-parathyroid, containing 115 amino acids, the predecessor of the substance after cell lysis in the thyroid becomes the second precursor substance,it is called parathyroid-hormone containing 90 amino acids , the latter becomes polypeptide containing 84 amino acids by cleaving within the cell, that is PTH. Normal human plasma PTH concentration is about 1 ng/ml.
The main physiological function of parathyroid hormone is promoting osteolysis, bone calcium mobilization into the blood, increasing calcium, increasing vigor of serum and bone alkaline phosphatase ;it can inhibit renal tubular reabsorption of phosphate, promote urinary excretion of phosphorus , decrease phosphorus; PTH via activation of vitamin D3, indirectly promotes intestinal absorption of calcium, magnesium and phosphorus. PTH secretion is mainly affected by the regulation of calcium concentration. Blood Ca2 + elevates, PTH secretion reduces; blood Ca2 + decreases, secretion is increased. In addition, phosphorus increasing via reducing calcium stimulates the secretion of PTH, calcitonin massive release can also promote increasing secretion of PTH.
Serum parathyroid hormone except for the study of parathyroid disease, has a certain value on the differential diagnosis of hypercalcemia and hypocalcemia The main clinical significance is as follows:
1. Diagnosis of parathyroid disease. When there are hyperparathyroidism or ectopic PTH secretion disorder, PTH increases ; when there are hypoparathyroidism, parathyroid surgery or radiation damage, etc., PTH decreases.
2. Identification of hypercalcemia and hypocalcemia. When abnormal calcium is caused by calcium parathyroid disorders ,serum calcium lifts as serum PTH lifts, while abnormal blood calcium is caused by other causes , PTH does not change.
The above information is edited by the Chemicalbook of Tian Ye. |
China
