HCG is a glycoprotein hormone secreted by the developing placenta during pregnancy. The concentration of HCG in serum is approximately equal to the concentration in urine. The concentrations of HCG in urine and serum continue to rise during the first trimester of pregnancy to as high as 100, 000mIU/ml. HCG appears in serum and urine shortly after conception, and continues to increase during the early stages of pregnancy, making it an excellent indicator for the detection of pregnancy.
The membrane of the test device was coated with anti HCG antibodies on the test region and goat anti mouse IgG antibodies on the control region. During the test, urine specimen is allowed to react with the HCG monoclonal antibody-colloid gold conjugate, which was pre-dried on the test strip. The mixture then moves upward on the membrane chromatographically by capillary action. For a positive specimen, the conjugate binds to the HCG forming an antibody-antigen complex. This complex is captured by anti HCG antibody immobilized on the test region (T) and produces a pink color band when HCG concentration is equal to or greater than 25mIU/ml. Absence of this colored band in the test region suggests a negative result. To serve as a procedural control, a colored band at the control region(C) will always appear regardless the presence or absence of HCG.