Delta values of nandrolone and testosterone products available in the UK; Implications for anti-doping?

Anabolic androgenic steroids (AAS) are the most widely abused class of drugs by athletes, and thus represent a significant problem to the anti-doping community. Confirmation of a doping violation for AAS cannot always be based on their presence alone due to the endogenous production of some steroids. Both testosterone (and its metabolites) and the major diagnostic metabolite of nandrolone (19-norandrosterone) are produced endogenously. Gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) is used in such cases to differentiate between the administration of a synthetic preparation and endogenous steroid production, by measurement of their differing carbon isotope (13C/12C) ratio. The availability of synthetic steroid preparations with a 13C content analytically indistinguishable from that of endogenous steroids would prevent the confirmation of a doping violation. The purpose of this study was to investigate the potential availability of such steroid preparations in the UK. Fourteen preparations containing nandrolone (n = 9) and testosterone (n = 5) were analysed. The δ 13C values were determined using GC-C-IRMS, and the identity of the steroid preparations was confirmed using gas chromatography mass spectrometry (GC-MS). Ten steroid preparations displayed δ 13C values within the range expected for synthetic steroids (less than -27 ‰). However, four nandrolone preparations displayed δ13C values that overlap with the values considered to be endogenous in origin (range -26 to -16 ‰). Misuse of these preparations could prevent the confirmation of nandrolone administration using GC-C-IRMS in anti-doping cases.