In this assay the Cystatin C present in samples reacts with the anti-Cystatin Cantibodies which have been adsorbed to the surface of polystyrene microtitre wells. After the removal of unbound proteins by washing, anti-Cystatin C antibodies conjugated with horseradish peroxidase (HRP), are added. These enzyme-labeled antibodiesform complexes with the previously bound Cystatin C.