title: Longitudinal profiling of urinary steroids by gas chromatography/combustion/isotope ratio mass spectrometry: diet change may result in carbon isotopic variations.
abstract: Longitudinal profiling of urinary steroids was investigated by using a gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) method. The carbon isotope ratio of three urinary testosterone (T) metabolites: androsterone, etiocholanolone, 5beta-androstane-3alpha,17beta-diol (5beta-androstanediol) together with 16(5alpha)-androsten-3alpha-ol (androstenol) and 5beta-pregnane-3alpha,20alpha-diol (5beta-pregnanediol) were measured in urine samples collected from three top-level athletes over 2 years. Throughout the study, the subjects were living in Switzerland and were residing every year for a month or two in an African country. (13)C-enrichment larger than 2.5 per thousand was observed for one subject after a 2-month stay in Africa. Our findings reveal that (13)C-enrichment caused by a diet change might be reduced if the stay in Africa was shorter or if the urine sample was not collected within the days after return to Switzerland. The steroids of interest in each sample did not show significant isotopic fractionation that could lead to false positive results in anti-doping testing. In contrast to the results obtained with the carbon isotopic ratio, profiling of urinary testosterone/epitestosterone (T/E) ratios was found to be unaffected by a diet change.
authors.affiliation: Laboratoire Suisse d'Analyse du Dopage, Institut Universitaire de Médecine Légale, Rue du Bugnon 21, 1005 Lausanne, Switzerland. christophe.saudan@chuv.ch
authors.forename: Christophe
authors.initials: C
authors.lastname: Saudan
authors.forename: Matthias
authors.initials: M
authors.lastname: Kamber
authors.forename: Giulia
authors.initials: G
authors.lastname: Barbati
authors.forename: Neil
authors.initials: N
authors.lastname: Robinson
authors.forename: Aurélien
authors.initials: A
authors.lastname: Desmarchelier
authors.forename: Patrice
authors.initials: P
authors.lastname: Mangin
authors.forename: Martial
authors.initials: M
authors.lastname: Saugy
mesh_terms: D000328:Adult; D002247:Carbon Isotopes / Q000032:analysis; D002849:Chromatography, Gas / Q000379:methods*; D004032:Diet; D004300:Doping in Sports; D004845:Epitestosterone / Q000652:urine; D006801:Humans; D007630:Kenya; D008137:Longitudinal Studies; D008297:Male; D013058:Mass Spectrometry / Q000379:methods*; D012420:Running / Q000502:physiology; D013019:South Africa; D013256:Steroids / Q000652:urine*; D013557:Switzerland; D013739:Testosterone / Q000652:urine
chemical_list: D002247:Carbon Isotopes; D013256:Steroids; D013739:Testosterone; D004845:Epitestosterone