The membrane of the test device was coated with anti TSH antibodies on the test region and goat anti mouse IgG antibodies on the control region. During the test, blood specimen is allowed to react with the TSH 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 TSH forming an antibody-antigen complex. This complex is captured by anti TSH antibody immobilized on the test region (T) and produces a pink color band when TSH is detected. The color intensity of T line reflect the concentration of TSH in human blood. Read the test in the Rapid Immuno Assay Reader for the quantitative value.