Carbon isotope ratio (δ 13C) values of urinary steroids for doping control in sport

• Published in: Steroids 2009-03, Vol.74 (3), p.379-392
• Main Authors: Cawley, Adam T., Trout, Graham J., Kazlauskas, Rymantas, Howe, Christopher J., George, Adrian V.
• Format: Article
• Language: English
• Subjects: Carbon isotope ratio (δ 13C); Carbon Isotopes - analysis; Doping control; Doping in Sports; Endogenous steroids; Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS); Gas Chromatography-Mass Spectrometry - methods; Humans; Steroids - urine; Substance Abuse Detection - methods; Testosterone
• ISSN: 0039-128X; 1878-5867
• DOI: 10.1016/j.steroids.2008.11.004

The detection of steroids originating from synthetic precursors in relation to their chemically identical natural analogues has proven to be a significant challenge for doping control laboratories accredited by the World Anti-Doping Agency (WADA). Endogenous steroid abuse may be confirmed by utilising the atomic specificity of gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) that enables the precise measurement of differences in stable isotope ratios that arise as a result of fractionation patterns inherent in the source of steroids. A comprehensive carbon isotope ratio (δ 13C) profiling study ( n = 1262) of urinary ketosteroids is reported that demonstrates the inter-individual variation that can be expected from factors such as diet, ethnicity, gender and age within and between different populations (13 countries). This δ 13C distribution is shown by principal component analysis (PCA) to provide a statistical comparison to δ 13C values observed following administration of testosterone enanthate. A limited collection of steroid diol data ( n = 100; consisting of three countries) is also presented with comparison to δ 13C values of excreted testosterone to validate criteria for WADA accredited laboratories to prove doping offences.