title: Urinary analysis of four testosterone metabolites and pregnanediol by gas chromatography-combustion-isotope ratio mass spectrometry after oral administrations of testosterone.
abstract: The most frequently used method to demonstrate testosterone abuse is the determination of the testosterone and epitestosterone concentration ratio (T/E ratio) in urine. Nevertheless, it is known that factors other than testosterone administration may increase the T/E ratio. In the last years, the determination of the carbon isotope ratio has proven to be the most promising method to help discriminate between naturally elevated T/E ratios and those reflecting T use. In this paper, an excretion study following oral administration of 40 mg testosterone undecanoate initially and 13 h later is presented. Four testosterone metabolites (androsterone, etiocholanolone, 5 alpha-androstanediol, and 5 beta-androstanediol) together with an endogenous reference (5 beta-pregnanediol) were extracted from the urines and the delta(13)C/(12)C ratio of each compound was analyzed by gas chromatography-combustion-isotope ratio mass spectrometry. The results show similar maximum delta(13)C-value variations (parts per thousand difference of delta(13)C/(12)C ratio from the isotope ratio standard) for the T metabolites and concomitant changes of the T/E ratios after administration of the first and the second dose of T. Whereas the T/E ratios as well as the androsterone, etiocholanolone and 5 alpha-androstanediol delta(13)C-values returned to the baseline 15 h after the second T administration, a decrease of the 5 beta-androstanediol delta-values could be detected for over 40 h. This suggests that measurements of 5 beta-androstanediol delta-values allow the detection of a testosterone ingestion over a longer post-administration period than other T metabolites delta(13)C-values or than the usual T/E ratio approach.
authors.affiliation: Laboratoire Suisse d'Analyse du Dopage, Institut Universitaire de Médecine Légale, Rue du Bugnon 21, 1005 Lausanne, Switzerland.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Maître
authors.forename: Christophe
authors.initials: C
authors.lastname: Saudan
authors.forename: Patrice
authors.initials: P
authors.lastname: Mangin
authors.forename: Martial
authors.initials: M
authors.lastname: Saugy
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000465:Algorithms; D000728:Androgens / Q000652:urine; D001711:Biotransformation; D002245:Carbon Dioxide / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D011276:Pregnanediol / Q000652:urine*; D012997:Solvents; D013739:Testosterone / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000652:urine*
chemical_list: D000728:Androgens; D012997:Solvents; D002245:Carbon Dioxide; D013739:Testosterone; D011276:Pregnanediol