An ELISA for pregnancy-associated plasma protein A

An enzyme-linked immunoassay for pregnancy-associated plasma protein A is described. The assay is sensitive (7.6 IU/l) and precise (overall CV varied between 8.9% and 10.8%). Recovery was 100% over the working range. Parallel behaviour was observed between the International Reference Preparation 78/610 and pregnancy serum, thus allowing calibration of a laboratory standard pool against IRP 78/610.