A rapid visual enzyme immunoassay for the qualitative determination of human chorionic gonadotropin (hCG) in urine or serum.
Human chorionic gonadotropin (hCG) is a glycoprotein hormone secreted by the developing placenta shortly after fertilization. In normal pregnancy, hCG can be detected generally as early as 7 days following conception (1-4), doubling every 1.3 to 2 days.At the time of the first missed menstrual period, hCG concentration is about 100mIU/mL, and peak levels of 100,000 – 200,000mIU/mL are seen at the end of the first trimester.The appearance of hCG soon after conception and its subsequent rise in concentration during early gestational growth make it an excellent marker for the early detection of pregnancy. (5) Elevated hCG levels comparable to those observed in early pregnancy may also be associated with trophoblastic or non-trophoblastic neoplasm (6-7) such as hydatidiform mole, choriocarcinoma; therefore, the possibility of such disease should be ruled out
before a positive hCG result is considered diagnostic for pregnancy.
The HCG (visual) ELISA is a sandwich enzyme immunoassay (8-9) for the determination of human chorionic gonadotropin in urine or serum. The method employs two monoclonal antibodies to selectively identify hCG in urine/serum with a high degree of sensitivity.In less than 10 minutes, elevated levels of hCG as little as 20mIU/mL can be detected. The patientÕs specimen is allowed to react with the antibody enzyme conjugate and the antibodies on the solid phase simultaneously. In the presence of hCG, a specific antibody-hCG-antibody-enzyme complex will form on the surface of microtiter well. After unbound enzyme conjugate is removed by rinsing under a stream of distilled water, the well is incubated with TMB Reagent.The development of blue color in the well indicated the presence of hCG. Comparing the color intensity of patient samples with that of the provided known
reference, the amount of hCG can be visually estimated to be greater or less than 20 mIU/mL.