Quantitation of human chorionic gonadotrophin by the planimetry of latex agglutination-inhibition results on microtiter plates.

A new type of heavy latex particle (LP) coated with the conjugates of human chorionic gonadotrophin (hCG) and bovine serum albumin (BSA) was used as indicator for the microtiter agglutination-inhibition assay of hCG using a monoclonal antibody (McAb) to hCG. The precipitation patterns of LP were measured by an automatic planimetry system. The detection limit of this method was 4 to 8 IU/l. Human luteinizing hormone (hLH) and follicle-stimulating hormone (FSH) caused hardly any cross-reaction in the presence of 3,350 IU/l and 1,500 IU/l, respectively. This planimetric immunoassay (PMIA) method provides a potentially useful method for hormone assay.