Deuterium labelled steroid hormones: tracers for the measurement of androgen plasma clearance rates in women.

A method employing stable isotope-labelled tracers and gas chromatograph-mass spectrometry (GC-MS) analysis has been used to measure the plasma clearance rates (PCR's) of androstenedione (A) and testosterone (T) in normal women and women with androgen abnormalities including hirsutism and polycystic ovary syndrome. A solution of deuterium-labelled A and T is infused at a constant rate and blood samples taken at 2 and 2.25 h. Solvent extracts of the derived plasma samples, to which an internal standard has been added, are derivatized with pentafluoropropionic anhydride and the endogenous steroid and deuterated steroid are quantitated after an injection of the derivatization mixture into a capillary column GC-MS. The concentration of the deuterated steroid in the infusion mixture is measured and the PCR is calculated. In premenopausal normal women the PCRA is 1950 +/- 184 1/24 h (n = 5) and the PCRT is 484 +/- 82 1/24 h (n = 7).