Determination of estrogen ring D glucuronides in pregnancy plasma by direct radioimmunoassay without hydrolysis.

A direct radioimmunoassay method using highly specific antisera without prior deconjugation has been developed for determination of estradiol 17-glucuronide and estriol 16-glucuronide in human plasma. Antisera were elicited in the rabbit by immunization with antigens in which the steroid haptens are linked to a carrier protein through the C-2 or C-4 position. After treatment with Rivanol the protein of albumin-free antiserum was covalently bound to a p-arylamine glass bead support through the cross-linkage with glutaraldehyde. A simple and reliable assay method employing the antibody-glass preparation was established and applied to measurement of estrogen ring D glucuronide concentration in peripheral plasma throughout normal pregnancy.