title: Nickel in equine sports drug testing - pilot study results on urinary nickel concentrations.
abstract: BACKGROUND
  The issue of illicit performance enhancement spans human and animal sport in presumably equal measure, with prohibited substances and methods of doping conveying both ways. Due to the proven capability of unbound ionic cobalt (Co(2) (+) ) to stimulate erythropoiesis in humans, both human and equine anti-doping regulations have listed cobalt as a banned substance, and in particular in horse drug testing, thresholds for cobalt concentrations applying to plasma and urine have been suggested or established. Recent reports about the finding of substantial amounts of undeclared nickel in arguably licit performance- and recovery-supporting products raised the question whether the ionic species of this transition metal (Ni(2) (+) ), which exhibits similar prolyl hydroxylase inhibiting properties to Co(2) (+) , has been considered as a substitute for cobalt in doping regimens.
  
  
  METHODS
  Therefore, a pilot study with 200 routine post-competition doping control horse urine samples collected from animals participating in equestrian, gallop, and trotting in Europe was conducted to provide a first dataset on equine urinary Ni(2) (+) concentrations. All specimens were analyzed by conventional inductively coupled plasma mass spectrometry (ICP-MS) to yield quantitative data for soluble nickel.
  
  
  RESULTS
  Concentrations ranging from below the assay's limit of quantification (LOQ, 0.5 ng/mL) up to 33.4 ng/mL with a mean value (± standard deviation) of 6.1 (±5.1) ng/mL were determined for the total nickel content.
  
  
  CONCLUSIONS
  In horses, nickel is considered a micronutrient and feed supplements containing nickel are available; hence, follow-up studies are deemed warranted to consolidate potential future threshold levels concerning urine and blood nickel concentrations in horses using larger sets of samples for both matrices and to provide in-depth insights by conducting elimination studies with soluble Ni(2) (+) -salt species. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Center for Preventive Doping Research - Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.|European Monitoring Center for Emerging Doping Agents (EuMoCEDA), Cologne/Bonn, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Thevis
authors.affiliation: Center for Preventive Doping Research - Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Machnik
authors.affiliation: Center for Preventive Doping Research - Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Schenk
authors.affiliation: Center for Preventive Doping Research - Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.|European Monitoring Center for Emerging Doping Agents (EuMoCEDA), Cologne/Bonn, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Krug
authors.affiliation: Center for Preventive Doping Research - Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Piper
authors.affiliation: Center for Preventive Doping Research - Institute of Biochemistry, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933, Cologne, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Schänzer
authors.affiliation: Deutsche Reiterliche Vereinigung e.V. (FN), 48231, Warendorf, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Düe
authors.affiliation: Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123, Uppsala, Sweden.|National Veterinary Institute (SVA), Department of Chemistry, Environment and Feed Hygiene, SE-751 89, Uppsala, Sweden.
authors.forename: U
authors.initials: U
authors.lastname: Bondesson
authors.affiliation: Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123, Uppsala, Sweden.|National Veterinary Institute (SVA), Department of Chemistry, Environment and Feed Hygiene, SE-751 89, Uppsala, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Hedeland
mesh_terms: D000818:Animals; D004300:Doping in Sports; D005260:Female; D006736:Horses / Q000502:physiology*; D008297:Male; D013058:Mass Spectrometry; D009532:Nickel / Q000652:urine*; D010865:Pilot Projects
chemical_list: D009532:Nickel