title: Reticulocyte and haemoglobin profiles in elite triathletes over four consecutive seasons.
abstract: BACKGROUND
  The World Anti-Doping Agency has implemented the Blood Passport in attempt to detect blood doping in athletes. The Blood Passport looks for uncommon changes overtime in reticulocytes percentage (Ret %), as a variable of the OFF-hr score, and haemoglobin concentration ([Hb]) reflecting potential doping violations. Few studies, however, have actually investigated the concurrent stability of Ret % and [Hb] in athletes over extended periods of time, none of which were measured in athletes who undergo strenuous and prolonged physical exercise.
  
  
  METHODS
  Measurements of Ret % and [Hb] were assessed over the course of four competitive seasons in elite triathletes (10 males and seven female). Blood was obtained at the start of the season, precompetitive period, competitive period and at the end of the competitive period.
  
  
  RESULTS
  Differences (P<0.001) were observed in both [Hb] and Ret % between genders and there was a high variability between subjects. Neither males nor females exhibited differences in [Hb] across all periods within one season. Within gender, analysis revealed that Ret % varied significantly (P=0.0018) between periods only in female athletes.
  
  
  CONCLUSIONS
  We conclude that Ret % and [Hb] remain stable over four consecutive seasons in elite triathletes, confirming that both parameters are valid for antidoping purposes based on the Blood Passport. In addition, Ret % fluctuations within one season require further investigation in females.
authors.affiliation: Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: V
authors.initials: V
authors.lastname: Díaz
authors.forename: G
authors.initials: G
authors.lastname: Lombardi
authors.forename: C
authors.initials: C
authors.lastname: Ricci
authors.forename: R A
authors.initials: RA
authors.lastname: Jacobs
authors.forename: Z
authors.initials: Z
authors.lastname: Montalvo
authors.forename: C
authors.initials: C
authors.lastname: Lundby
authors.forename: G
authors.initials: G
authors.lastname: Banfi
mesh_terms: D000328:Adult; D056352:Athletes; D001642:Bicycling; D004300:Doping in Sports; D005260:Female; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D058573:Performance-Enhancing Substances / Q000097:blood; D015203:Reproducibility of Results; D017701:Reticulocyte Count; D012156:Reticulocytes / Q000166:cytology*; D012420:Running; D012621:Seasons; D012737:Sex Factors; D015813:Substance Abuse Detection / Q000379:methods; D013550:Swimming; D013997:Time Factors; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D058573:Performance-Enhancing Substances