METHODS OF STEROID-RECEPTOR CALCULATION - INTER-LABORATORY STUDY

Data from a determination of progesterone receptors in a human endometrial cytosol preparation were sent to 28 specialist laboratories with a request for details of calculations of receptor parameters normally carried out. The 18 replies received included data from two further laboratories in contact with one of the recipients of the questionnaire, and 12 recipients did not reply. Our own results have been included in the survey. Six different methods of calculation were used and up to four points of a seven point assay were rejected. The estimates of receptor binding site concentration varied between 3.3 and 29 nM (or, rejecting the highest value, between 3.3 and 5.2 nM) and those of the dissociation constant varied between 0.43 and 59 nM (or, rejecting the highest value, between 0.43 and 7.8 nM). The shapes of the binding curves and the methods of calculation are discussed. © 1979.