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Detection of testosterone administration based on the carbon isotope ratio profiling of endogenous steroids: international reference populations of professional soccer players
  1. E Strahm1,
  2. C Emery1,
  3. M Saugy1,
  4. J Dvorak2,
  5. C Saudan1
  1. 1
    Swiss Laboratory for Doping Analyses, University Center of Legal Medicine, West Switzerland, Epalinges, Switzerland
  2. 2
    FIFA Medical Assessment and Research Centre, Zürich, Switzerland
  1. Correspondence to C Saudan, Swiss Laboratory for Doping Analyses, University Center of Legal Medicine, West Switzerland, Chemin des Croisettes 22, 1066 Epalinges, Switzerland; Christophe.Saudan{at}


Background and objectives: The determination of the carbon isotope ratio in androgen metabolites has been previously shown to be a reliable, direct method to detect testosterone misuse in the context of antidoping testing. Here, the variability in the 13C/12C ratios in urinary steroids in a widely heterogeneous cohort of professional soccer players residing in different countries (Argentina, Italy, Japan, South Africa, Switzerland and Uganda) is examined.

Methods: Carbon isotope ratios of selected androgens in urine specimens were determined using gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS).

Results: Urinary steroids in Italian and Swiss populations were found to be enriched in 13C relative to other groups, reflecting higher consumption of C3 plants in these two countries. Importantly, detection criteria based on the difference in the carbon isotope ratio of androsterone and pregnanediol for each population were found to be well below the established threshold value for positive cases.

Conclusions: The results obtained with the tested diet groups highlight the importance of adapting the criteria if one wishes to increase the sensitivity of exogenous testosterone detection. In addition, confirmatory tests might be rendered more efficient by combining isotope ratio mass spectrometry with refined interpretation criteria for positivity and subject-based profiling of steroids.

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  • Competing interests None declared.

  • Ethics approval The study was initiated after validation of the protocol by the ethical committee of the University of Lausanne, Switzerland.

  • Provenance and Peer review Not commissioned; externally peer reviewed.

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