title: [13C]Nandrolone excretion in trained athletes: interindividual variability in metabolism.
abstract: BACKGROUND
  Nandrolone is one of the most abused anabolic steroids, and its use in doping is increasing, as revealed by numerous positive cases during recent years in various sports. Different authors have reported the possible natural production of nandrolone metabolites in humans, and some of these authors argued that exhaustive exercise could increase nandrolone production in the body or induce dehydration and consequently lead to an increase of nandrolone metabolites in urine.
  
  
  METHODS
  Volunteers (n = 22) ingested two 25-mg doses of [(13)C]nandrolone at 24-h intervals and collected urine specimens for 5 days. The labeled nandrolone metabolites 19-norandrosterone and 19-noretiocholanolone were identified and quantified by gas chromatography-mass spectrometry.
  
  
  RESULTS
  Interindividual variability was observed in nandrolone excretion patterns and kinetics, as well as for the noretiocholanolone:norandrosterone ratio. The amounts of nandrolone metabolites measured at the excretion peak varied between 1180 and 38 661 microg/L for norandrosterone and 576 and 12 328 microg/L for noretiocholanolone. At the end of the excretion period, the noretiocholanolone:norandrosterone ratio was sometimes >1. The analysis of numerous spot-urine samples allowed the determination of an acceptable correlation between urinary creatinine and specific gravity for placebo- and steroid-treated individuals: y = 0.0052ln(x) + 1.0178 (r(2) = 0.8142) and y = 0.0068ln(x) + 1.0172 (r(2) = 0.7730), respectively.
  
  
  CONCLUSIONS
  The excretion kinetics and patterns of labeled nandrolone show interindividual variability. More investigations are currently underway to estimate the influence of exhaustive exercises on excretion of labeled nandrolone metabolites in urine.
authors.affiliation: Laboratoire suisse d'Analyse du Dopage, Institut de Médecine Légale, Département Universitaire de Médecine et Santé Communautaires, Lausanne, Switzerland.
authors.forename: Norbert
authors.initials: N
authors.lastname: Baume
authors.forename: Lidia
authors.initials: L
authors.lastname: Avois
authors.forename: Carine
authors.initials: C
authors.lastname: Schweizer
authors.forename: Christine
authors.initials: C
authors.lastname: Cardis
authors.forename: Jiri
authors.initials: J
authors.lastname: Dvorak
authors.forename: Michel
authors.initials: M
authors.lastname: Cauderay
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; D004300:Doping in Sports; D004962:Estranes / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D009277:Nandrolone / Q000378:metabolism* / Q000493:pharmacokinetics / Q000652:urine; D013177:Sports; D015813:Substance Abuse Detection
chemical_list: D002247:Carbon Isotopes; D004962:Estranes; C036015:19-norandrosterone; D009277:Nandrolone