Total estriol in serum and plasma as determined by radioimmunoassay

We present and discuss the results of a statistical study of a set of radioimmunoassay data obtained from parallel determinations of the total estriol content of samples of serum and plasma prepared from 98 specimens of whole blood, taken from pregnant woman. Estriol concentrations in the serum exceed by an average of 7% the values found for the plasma prepared from the same whole-blood specimen. The clinical significance of this analytical finding is discussed, and we conclude with the recommendation that serum is the fluid of choice for this assay.