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ABSTRACT A method for the measurement of plasma testosterone (T) by competitive protein binding analysis is described. An ether extract of 5.0 ml plasma is purified by a single thin layer chromatographic step prior to analysis. Third trimester pregnancy plasma diluted 1:100 is reacted at 4 C, and a viscous suspension of charcoal in dextran is utilized to separate bound from free T. T is measured with high accuracy (b=0.963, r =0.919) and sensitivity (0.25–2.5 ng/sample). Precision (15%) and specificity are suitable for clinical use. The mean plasma T found in normal females is 46.5 ±19.3 ng/100 ml (range 32.2–70.3) and in normal males 533±259 ng/100 ml (range 238–1001).
Rosenfield et al. (1969) studied this question.