This assay employs the competitive inhibition enzyme immunoassay technique. A monoclonal antibody specific to Alpha-2-Macroglobulin (a2M) has been pre-coated onto a microplate. A competitive inhibition reaction is launched between biotin labeled Alpha-2-Macroglobulin (a2M) and unlabeled Alpha-2-Macroglobulin (a2M) (Standards or samples) with the pre-coated antibody specific to Alpha-2-Macroglobulin (a2M). After incubation the unbound conjugate is washed off. Next, avidin conjugated to Horseradis