Evaluation and clinical application of a dextran-charcoal method for measuring bound testosterone in human plasma.

A method for rapidly determining bound and free testosterone in human plasma is evaluated and described, in which dextran-coated charcoal is used to separate bound and free testosterone. Intra- and inter-assay CV's were 1.9 and 3.8%, respectively. At least 50% of the "bound" testosterone was associated with species that behaved like sex steroid hormone-binding globulin on Sephadex G-25 chromatography and polyacrylamide gel electrophoresis. Bound and free testosterone concentrations were determined in normal men, normal women (during the menstrual cycle and during normal pregnancy), and in women with various degrees of hirsutism. We conclude that determining the circulating proportions of bound and free testosterone is helpful in the diagnostic evaluation of hirsutism in women, and in the investigation of normal and pathological conditions where androgen concentrations may be altered.