Routine radioimmunoassay of plasma testosterone, and results for various endocrine disorders.

We describe a modification of published methods for radioimmunoassay of plasma testosterone. This simpler method involves no chromatographic steps, and the necessary reagents, including tritiated testosterone and testosterone anti-serum, are commercially available. A digital computer is used for the calculation. Without difficulty, a technician can complete 100 assays in three working days. Mean testosterone concentrations (plus or minus 2 SD) in the plasmas of 21 normal men and 26 women with a normal menstrual cycle were 684 plus or minus 300 and 45 plus or minus 20 ng/dl, respectively. Within- and between-assay precision (coefficient of variation) were 5.2% (n = 29) and 6.7% (n = 26), respectively. We have assayed more than 1000 samples during the past year. We give data on the concentrations of testosterone in plasma of patients with various endocrine disorders.