title: Formation of androstanediol from 13C-labeled testosterone in humans.
abstract: The determination of urinary 5 alpha-androstane-3 alpha,17 beta-diol (3a-Diol) by gas chromatography/mass spectometry during and after the infusion of stable-labeled testosterone (T) represents an alternative to the use of radioactive label for turnover studies in vivo. Using this methodology to assess the urinary excretion rates of T and 3a-Diol in healthy men (n = 6) and women (n = 5) during and after the intravenous infusion (t = 4 hours) of 20 mg (men) or 5 mg (women) [13C]testosterone, the cumulative renal excretion of 13C-labeled T was found to be 15.6 +/- 9.6 micrograms/24 hours (men) and 1.1 +/- 1.6 micrograms/24 hours (women), equivalent to 0.08% +/- 0.05% and 0.02% +/- 0.03% of the infused amount of 13C-T, respectively. The cumulative excretion of 13C-3a-Diol was 67.7 +/- 19.9 micrograms/24 hours (men) and 10.0 +/- 6.0 micrograms/24 hours (women), equivalent to 0.3 +/- 0.1% and 0.2 +/- 0.1% of the infused dose of 13C-labeled testosterone, respectively.
authors.affiliation: Division of Clinical Endocrinology and Diabetes Mellitus, I. Medizinische Universitätsklinik, Wien, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Vierhapper
mesh_terms: D000328:Adult; D015113:Androstane-3,17-diol / Q000096:biosynthesis* / Q000652:urine; D000732:Androstanols; D002247:Carbon Isotopes; D013196:Dihydrotestosterone / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D013739:Testosterone / Q000378:metabolism*
chemical_list: D000732:Androstanols; D002247:Carbon Isotopes; D013196:Dihydrotestosterone; D015113:Androstane-3,17-diol; D013739:Testosterone