The use of multivariable standard curves in the radioimmunoassay of testosterone and 5alpha-dihydrotestosterone.

Multivariable calibration curves have been used to enable testosterone and 5alpha-dihydrostestosterone to be assayed directly in plasma extracts without further pre-purification of the sample. Two antisera were used, both with relatively high, but different affinities for the substances measured, and with relatively low affinity towards all other substances tested. The antisera were obtained from rabbits immunized against testosterone-3-BSA and 5alpha-dihydrostestosterone-3-BSA. The technique was of adequate precision, accuracy and specificity. The last was examined by comparison of values obtained by the present method and those obtained following prepurification by thin layer chromatography.