The test is a sandwich immunoassay. When serum sample is added to sample pad, it moves through the conjugate pad and mobilizes gold antibody conjugate that is coated on the conjugate pad. The mixture moves along the membrane by capillary action and reacts with anti-cardiac marker antibodies that is coated on the test region. If cardiac markers are present at levels of cut-off level or greater, the result is the formation of a colored band in the test region. If there are no cardiac markers in the sample, the area will remain colorless. The sample continues to move to the control area and forms a pink to purple color, indicating the test is working and the result is valid.
Below are the cut-off concentrations for each cardiac marker using in the test.
Troponin I 1.5 ng/mL ( Abbott AxSYM )*
CK-MB 7.0 ng/mL ( Abbott AxSYM )
Myoglobin 100 ng/mL ( Abbott AxSYM )
*The concentration of Troponin I is not standardized yet. The results from different assay system may vary significantly. Here is the summary of the sensitivity of the Troponin I Test Card on the major assay systems.