Effect of serum lipids on radioimmunoassays of unconjugated estriol in serum.

Abstract

Controversy regarding the presence of a circadian rhythm in unconjugated estriol in serum during pregnancy led us to study the possibility that the observed rhythms actually are the result of partitioning of estriol into serum lipids when these increase postprandially. Addition of triglycerides to purified estriol standards significantly decreased (p less than 0.001) apparent estriol as detected by radioimmunoassay after separation on dextran-coated charcoal and significantly increased (p less than 0.001) estriol as detected by radioimmunoassay after double-antibody separation. Compensation for individual nonspecific binding of standards nullified the effect of lipids only in systems involving dextran-coated charcoal separation, incubated for 1.0 h at 37 degrees C followed by 1.0 h at 4 degrees C. In contrast to other protocols, data obtained with this system revealed no significant circadian variation in serum estriol concentrations in normal pregnant women (CV, 4.3%). Evidently, reported variations in apparent serum estriol concentration are artifactual.

General Methods for the Extraction, Purification, and Measurement of Steroids by Chromatography and Mass Spectrometry

“…While in most instances, such material can be ignored, there are situations where it can assume importance, for example, in immunoassays where steroids extracted from biological matrices may not always behave in the same way as standard steroids used for the standard curve (e.g. Jawad et al, 1981). While many of these techniques are more than 20 years old, they should not be ignored and may still have applications to particular problems of today, especially when combined with more modern technology (e.g.…”

Ovarian early postovulatory development and oestrogen production in rainbow trout (Salmo gairdneri R.) from a spring-spawning strain

“…This result is opposite to those reported in other studies (Tcholakian and Steinberger, 1979;Ursely et al, 1981) where RIA appeared to overestimate aromatase activity, possibly by lack of specificity. In our work, interference of lipids in RIA (Jawad et al, 1981) and isotope effect on metabolism and/or analysis (Kelly et al, 1979) might be responsible for the discrepancy between some of the estimates.…”