title: Isotopic fractionation of endogenous anabolic androgenic steroids and its relationship to doping control in sports.
abstract: The use of gas chromatography (GC)-combustion (C)-isotope ratio mass spectrometry (IRMS) demonstrates that a single oral administration of dehydroepiandrosterone (DHEA, 100 mg) to a male subject significantly lowers the 13C content of etiocholanolone (Et) and androsterone (A) in the subject's urine. The difference in carbon isotope ratio (d13C per thousand) values between Et and A increases from 1.6 per thousand at the time of administration to 5.1 per thousand at 26 h post-administration, indicating preferential metabolism of administered DHEA to form Et in relation to A. Multiple oral administrations of DHEA to a male subject reveals lower d13C values during the excretion period of Et (-31.7 per thousand to -34.6 per thousand) and A (-31.4 per thousand to -33.0 per thousand) to that of the d13C value of the administered DHEA (-31.3 per thousand). Reference distributions of d13C Et and d13C A constructed from normal athlete populations within Australia and New Zealand show a small natural discrimination against 13C in the formation of Et relative to A (mean=0.3 per thousand, n=167, p=0.007). Amplified differences between d13C Et and d13C A, and in vivo 13C depletion measured by GC-C-IRMS are shown to be potentially useful for doping control.
authors.affiliation: Research Chemist, Australian Sports Drug Testing Laboratory, National Measurement Institute, 1 Suakin Street, Pymble, NSW 2073, Australia.
authors.forename: Adam T
authors.initials: AT
authors.lastname: Cawley
authors.forename: Rymantas
authors.initials: R
authors.lastname: Kazlauskas
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Trout
authors.forename: Jill H
authors.initials: JH
authors.lastname: Rogerson
authors.forename: Adrian V
authors.initials: AV
authors.lastname: George
mesh_terms: D000328:Adult; D045930:Anabolic Agents / Q000302:isolation & purification*; D000728:Androgens / Q000302:isolation & purification*; D000738:Androsterone / Q000652:urine; D001315:Australia; D002247:Carbon Isotopes / Q000652:urine; D005591:Chemical Fractionation / Q000379:methods*; D003687:Dehydroepiandrosterone / Q000008:administration & dosage / Q000493:pharmacokinetics; D004300:Doping in Sports / Q000517:prevention & control*; D005043:Etiocholanolone / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D008297:Male; D009520:New Zealand; D013177:Sports
chemical_list: D045930:Anabolic Agents; D000728:Androgens; D002247:Carbon Isotopes; D003687:Dehydroepiandrosterone; D005043:Etiocholanolone; D000738:Androsterone