A Competitive lmmunoenzymometricAssay for Albumin in Urine

I describe a competitive immunoenzymometric assay for urinary albumin, with use of an immobilized albumin-thyro-globulin conjugate and an affinity-purified antibody. The assay is rapid, easy to perform, has a range of 0.5 to 78 mgIL, and is ideally suited for screening purposes. Higher concentrationsmay be assayed by further dilution of the urine sample. Results compare favorably with those of a commerciallyavailable radioimmunoassay kit. Additional Keyphrases: thyroglobulinas a carrier radioimmu-noassay compared The recent publications of methods (1-3) for urinary albumin reflect the current clinical interest in minimal albuminuria. The immunoenzymometric (EusA) methods (1,2) rely on the formation of a “sandwich ” comprising an antibody coated onto the plastic of the ELISA plate, the test antigen, and a second antibody (either conjugated to an enzyme or to be located by use of a third antibody-enzyme conjugate). When substrate is added to the system, color development is proportional to the concentration of the test antigen. Coating the ELISA plate with antigen simplifies the tech-nique to a procedure that is analogous with saturation analysis. I have compared results by the proposed method with those by a commercially availablekit produced specifi-cally for the assessment of albuminuria