Calbiotech PTH Elisa Kit

Product Description

SUMMARY AND EXPLANATION
PTH (Parathyroid hormone) is biosynthesized in the parathyroid gland as a pre-proparathyroid hormone, alarge molecular precursor consisting of 115 amino acids. After two intra-cellular proteolytic cleavage steps, theparathyroid gland secretes the final active form consisting of an 84 amino acid peptide. In healthy individuals,regulation of parathyroid hormone secretion normally occurs via a negative feedback action of serum calciumon the parathyroid glands. Intact PTH is biologically active and clears very rapidly from the circulation with ahalf-life of less than four minutes. Intact PTH assays are important for the differentiation of primaryhyperparathyroidism from other (non-parathyroid-mediated) forms of hypercalcemia, such as malignancy,sarcodosis and thyrotoxicosis. The measurement of parathyroid hormone is the most specific way of makingthe Diagnosis of primary hyperparathyroidism. In the presence of hypercalcemia, an elevated level ofparathyroid hormone virtually establishes the diagnosis. In over 90% of patents with primaryhyperparathyroidism, the parathyroid hormone will be elevated. The most common other cause ofhypercalcemia, namely hypercalcemia of malignancy, is associated with suppressed levels parathyroidhormone or PTH levels within the normal range. PTH values are typically undetectable in hypocalcemia due tototal hypoparathyroidism, but are found within the normal range in hypocalcemia due to partial loss or inhibitionof parathyroid function.

PRINCIPLE OF THE TEST
The Calbiotech Inc., Intact PTH Immunoassay is an adapted two-site sandwich ELISA. In this assay,standards and patient samples are simultaneously incubated with the enzyme labeled detection antibody and abiotin coupled capture antibody in a streptavidin-coated microplate well. At the end of the assay incubation,the microwell is washed to remove unbound components and the enzyme bound to the solid phase isincubated with the substrate, tetramethylbenzidine (TMB). An acidic stopping solution is then added to stopthe reaction and converts the color to yellow. The intensity of the yellow color is directly proportional to theconcentration of intact PTH in the sample. Standards are used to generate a dose response curve ofabsorbance unit vs. concentration. Concentrations of intact PTH present in the controls and patient samplesare determined directly from this curve.