Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by the developing placenta shortly after fertilization. In normal pregnancy, hCG can be detected in both serum and urine as early as 7 to 10 days after conception. hCG levels continue to rise very rapidly, frequently exceeding 100 mIU/ml by the first missed menstrual period, and peaking in the 100-200 mIU/ml range about 10-12 weeks into pregnancy. The sudden rapid rise in concentration of HCG following conception makes it an excellent marker for pregnancy.
The membrane is pre-coated with anti-hCG antibodies on the test band region and anti-mouse antibodies on the control band region. During testing, the urine sample reacts with the colored conjugate (mouse anti-hCG antibody colloidal gold conjugate) which has been pre-coated on the test strip. The mixture migrates upward on the membrane chromatographically by capillary action to react with anti-hCG antibodies on the membrane and generate a red band. Presence of the red band indicates a positive result, while its absence indicates a negative result. Regardless of the presence of hCG, as the mixture continues to migrate across the membrane to the immobilized goat anti-mouse region, a red band at the control band region will always appear. The presence of this red band serves as verification for sufficient sample volume and proper flow and as a control for the reagents.
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