Evaluation of azoestriol antisera for estriol measurements in pregnancy plasma directly and after extraction.

2-(4'-carboxyphenylazo)-estriol antisera were employed to quantitate pregnancy plasma estriol in ether extracts by single phase radioimmune assay without chromatography. Utilizing antiserum which crossreacted minimally even with the monoglucosiduronate metabolites, unextracted plasma estriol measurements were identical statistically to ether extract determinations.