Steroid receptors in human endometrium. Comparison of data obtained by three different methods

To find a method for steroid receptor measurement in small endometrial tissue samples (less than 100 mg), an isoelectric focusing assay has been compared with a dextran-coated charcoal assay for oestradiol receptor. The results correlated well (r = 0.85) and this indicates that isoelectric focusing is a good technique for oestradiol receptor determination. Te isoelectric focusing of progesterone receptor has been compared with a dextran-coated charcoal assay and sucrose density gradient centrifugation. Isoelectric focusing gave recoveries of 0-26% compared to receptor values obtained with the two other methods, which correlated well (r = 0.97). The low recovery implies that the isoelectric focusing assay is not suitable for progesterone receptor determination.