An enzyme immunoassay for the quantitative measurement of intact human chorionic gonadotropin (hCG) in serum or plasma.
Chorionic Gonadotropin (hCG) is a glycoprotein hormone which is normally produced by the placenta during pregnancy. After conception, the hCG concentration increases rapidly to reach a peak near the end of the first trimester. High concentrations are observed throughout pregnancy. After delivery, hCG levels fall rapidly and become undetectable after a few days. Structurally intact hCG molecules are composed of an alpha and a beta subunit with a molecular
weight of 38.4kDa. The alpha subunit is nearly identical to the alpha subunits of other glycoprotein hormones, such as Thyroid Stimulating Hormone (TSH), Luteinizing Hormone (LH), and Follicle Stimulating Hormone (FSH): The differences in the beta subunit of the respective hormones account for their biological specificity and immunochemical distinctiveness. Monoclonal antibodies recognizing unique sites on the beta chain of the hCG molecule are essential for differentiation between hCG and LH, FSH and TSH.HCG Assays are used for the early detection of pregnancy.
In addition to the elevated hCG levels during pregnancy, high concentrations of hCG may be associated with neoplasms of trophoblastic and nontrophoblastic origin such as hydatiform mole, chorionepithelioma, embryonal cell carcinoma, and many others. HCG is commonly elevated in different testicular tumors and is thus used as a tumor marker for testicular tumors in combination with AFP. There is a good correlation between changes in hCG levels and response to therapy. Extragonadal germ-cell cancers in the absence of clinically or ultrasonographically detectable testicular abnormalities have been observed as well. Over 50% of patients with malignant insulinomas have elevated hCG levels: the hormone is not detected in association with benign adenomas. Ectopic secretion of hCG also have been found in a small percentage of patients with adenocarcinoma of the ovary, pancreas and stomach, hepatomas, and islet-cell carcinomas.
The DRG HCG ELISA Kit is a solid phase enzyme-linked immunosorbent assay (ELISA) based on the sandwich principle. The microtiter wells are coated with a monoclonal [mouse] antibody directed towards a unique antigenic site on an hCG molecule. An aliquot of sample containing endogenous hCG is incubated in the coated well with enzyme conjugate, which is a monoclonal antibody directed against the alpha-chain of hCG conjugated with horseradish peroxidase. After incubation the unbound conjugate is washed off. The amount of bound peroxidase is proportional to the concentration of hCG in the sample. Having added the substrate solution, the intensity of color developed is proportional to the concentration of hCG in the sample.