title: A pilot study on subject-based comprehensive steroid profiling: novel biomarkers to detect testosterone misuse in sports.
abstract: BACKGROUND
  Until now, the testosterone/epitestosterone (T/E) ratio is the main marker for the detection of testosterone (T) misuse in athletes. As this marker can be influenced by a number of confounding factors, additional steroid profile parameters indicating T misuse can provide substantiating evidence of doping with endogenous steroids. The evaluation of a steroid profile is currently based upon population statistics. As large inter-individual variations exist, a paradigm shift towards subject-based references is ongoing in doping analysis.
  
  
  OBJECTIVE
  Proposition of new biomarkers for the detection of testosterone in sports using extensive steroid profiling and an adaptive model based upon Bayesian inference.
  
  
  METHODS
  Six healthy male volunteers were administered with testosterone undecanoate. Population statistics were performed upon steroid profiles from 2014 male Caucasian athletes participating in official sport competition.
  
  
  METHODS
  An extended search for new biomarkers in a comprehensive steroid profile combined with Bayesian inference techniques as used in the athlete biological passport resulted in a selection of additional biomarkers that may improve detection of testosterone misuse in sports.
  
  
  RESULTS
  Apart from T/E, 4 other steroid ratios (6α-OH-androstenedione/16α-OH-dehydroepiandrostenedione, 4-OH-androstenedione/16α-OH-androstenedione, 7α-OH-testosterone/7β-OH-dehydro-epiandrostenedione and dihydrotestosterone/5β-androstane-3α,17β-diol) were identified as sensitive urinary biomarkers for T misuse. These new biomarkers were rated according to relative response, parameter stability, detection time and discriminative power.
  
  
  CONCLUSIONS
  Newly selected biomarkers were found suitable for individual referencing within the concept of the Athlete's Biological Passport. The parameters showed improved detection time and discriminative power compared to the T/E ratio. Such biomarkers can support the evidence of doping with small oral doses of testosterone.
authors.affiliation: Docolab, Department of Clinical Chemistry, Microbiology and Immunology, University of Ghent, Zwijnaarde, BelgiumSwiss Laboratory for Doping Analysis, Université de Lausanne, Epalinges, Switzerland.
authors.forename: Pieter
authors.initials: P
authors.lastname: Van Renterghem
authors.forename: Peter
authors.initials: P
authors.lastname: Van Eenoo
authors.forename: Pierre-Edouard
authors.initials: PE
authors.lastname: Sottas
authors.forename: Martial
authors.initials: M
authors.lastname: Saugy
authors.forename: Frans
authors.initials: F
authors.lastname: Delbeke
mesh_terms: D000328:Adult; D000728:Androgens / Q000008:administration & dosage / Q000494:pharmacology / Q000652:urine*; D000731:Androstanes / Q000652:urine*; D015415:Biomarkers / Q000652:urine*; D004300:Doping in Sports / Q000517:prevention & control; D006801:Humans; D008297:Male; D010865:Pilot Projects; D012016:Reference Values; D015813:Substance Abuse Detection / Q000379:methods*; D013739:Testosterone / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D055815:Young Adult
chemical_list: D000728:Androgens; D000731:Androstanes; D015415:Biomarkers; D013739:Testosterone; C010792:testosterone undecanoate