A simultaneous assay to quantitate plasma and endometrial hormone concentrations

A method for radioimmunoassay determination of hormones in both plasma and endometrium is presented. Total estrogen (TE) and progesterone (P) concentrations were measured simultaneously in plasma and endometrium in 59 women throughout the menstrual cycle. TE values in endometrium showed an increase of 0.45 ng/gm wet tissue weight on days 7 to 9, reaching a peak of 4.89 ng/gm wet weight at midcycle; values of 2.2 ng/gm wet weight were constant during the secretory phase. The endometrial P concentrations were 5.31 and 44.93 ng/gm wet weight during the proliferative and luteal phases, respectively. Plasma P levels during the proliferative phase were below 1 ng/ml, in comparison with values above 5.71 ng/ml during the luteal phase. The quadratic coefficients of correlation between plasma and endometrial concentrations of TE and P were 0.8 and 0.9, respectively, indicating that under such conditions modifications in the amount of circulating hormones are reflected in the target tissue. These simultaneous studies may permit further investigation of the role of circulationg hormones in local biologic phenomena.