Special uses of a gas chromatograph-mass spectrometer in endocrinology.

Based on the isotope dilution principle, and using deuterium-labelled steroids as tracers combined with GC-MS analysis, clinically acceptable procedures for the measurement of daily urinary production rates (UPR's) and metabolic clearance rates (MCR's), of hormonal steroids, have been developed. In clinical tests, using progesterone and androstenedione as models the UPR's and MCR's obtained compared favourably with values obtained using radioisotope-labelled tracers. The heavy isotope procedure proved, however, to be superior to the radioisotope methods in accuracy, speed and patient safety.