A COMPARISON OF THREE METHODS OF MEASURING TESTOSTERONE IN PLASMA: COMPETITIVE PROTEIN BINDING, RADIOIMMUNOASSAY WITHOUT CHROMATOGRAPHY AND RADIOIMMUNOASSAY INCLUDING THIN LAYER CHROMATOGRAPHY

Abstract

ABSTRACT Three methods of measuring testosterone in male plasma were compared: A competitive protein binding technique using testosterone binding globulin, a radioimmunoassay including thin layer chromatography and a radioimmunoassay without chromatography. The antiserum obtained by immunization of rabbits with testosterone-3-(O-carboxymethyl)oximebovine-serum-albumin was characterized by its titer, affinity and specificity. The reliability criteria of the three methods were compared. Reagent blanks and the limit of detection were about 10 times higher in the competitive protein binding method than in the radioimmunoassay. The testosterone concentrations determined by the radioimmunoassay including chromatography and by the competitive protein binding method were in good agreement (y = 1.01 x, r = 0.96). There was a good agreement between the radioimmunoassay techniques (y = 1.05 x, r = 0.96). The results of the radioimmunoassay without chromatography were on an average 6.5 % higher than those of the radioimmunoassay including chromatography. The radioimmunoassay without chromatography is considered to be a reliable and practical routine method of measuring testosterone in male plasma. Normal values of 51 males ranged from 315 to 965 ng/100 ml (95 percentiles) with a median of 545 ng/100 ml.