PTH是甲状旁腺主细胞分泌的含有84个氨基酸的直链肽，分子量为9000，其生物活性决定于N端的第1-27个氨基酸残基。在甲状旁腺主细胞内先合成一个含有115个氨基酸的前甲状旁腺激素原（pre pro-PTH），以后脱掉N端二十五肽，生成九十肽的甲状旁腺激素原（pro-PTH），再脱去6个氨基酸，变成PTH，PTH释放入血后称全段PTH（intact PTH，I-PTH）。
本试剂盒采用双抗体夹心酶标免疫分析法测定标本中I-PTH水平。用纯化的抗体包被微孔板，制成固相抗体，往包被单抗的微孔中依次加入I-PTH抗原、生物素化的抗人I-PTH抗体、HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的I-PTH呈正相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the specific measurement of Human Intact-parathyroid hormone (I-PTH) concentrations in cell culture supernates, serum and plasma.
Introduction
Parathyroid hormone (iPTH intact parathyroid hormone) is an 84 amino acid polypeptide produced by the parathyroid gland with its biological activity residing in the N-terminal region of the peptide. PTH plays an important role in maintaining the concentration of ionized calcium within the limits needed to achieve normal metabolic functions. When serum calcium levels are decreased the parathyroid gland increases secretion of the hormone which results in increased mobilization of calcium from skeletal reserves into the circulation. When levels of serum calcium are increased the secretion of PTH is reduced.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for I-PTH has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any I-PTH present is bound by the immobilized antibody. An enzyme-linked monoclonal antibody specific for I-PTH is added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of I-PTH bound in the initial step. The color development is stopped and the intensity of the color is measured.
