PRINCIPLE OF THE TESTThe Calbiotech Bio-intact PTH (BiPTH) immunoassay is an adapted two-site sandwich ELISA. In this assay,standards and patient samples are simultaneously incubated with the enzyme labeled detection antibody(specific to 39-84 aa residue) and a biotin coupled capture antibody (specific to 1-6 aa residue) in astreptavidin-coated microplate well. At the end of the assay incubation, the microwell is washed to removeunbound components and the enzyme bound to the solid phase is incubated with the substrate,tetramethylbenzidine (TMB). An acidic stopping solution is then added to stop the reaction and converts thecolor to yellow. The intensity of the yellow color is directly proportional to the concentration of intact PTH in thesample. Standards are used to generate a dose response curve of absorbance unit vs. concentration.Concentrations of intact PTH present in the controls and patient samples are determined directly from thiscurve