Evaluation of endogenous steroid sulfates and glucuronides in urine after oral and transdermal administration of testosterone. Part I: Male participants

The detection of the performance-enhancing drug testosterone (T) remains a significant challenge in doping control analysis. Longitudinal monitoring through the steroidal Athlete Biological Passport (ABP) is a valuable tool for T detection, but further research is needed to enhance its efficacy. Phase II metabolites of endogenous anabolic androgenic steroids (EAAS), including glucuronides and sulfates, have gained increasing interest as potential new biomarkers for the steroidal ABP. Notably, sulfate metabolites have demonstrated higher sensitivity to oral, transdermal, and intramuscular T administration, with extended detection windows compared to traditional biomarkers. However, before incorporating these promising biomarkers into urinary steroid profiling, it is essential to address the metabolic variations associated with different T administration methods, as well as differences related to ethnicity and sex. In this part of the study, we investigate the effects of oral and transdermal T administration on conventional biomarkers and phase II EAAS metabolites in male participants. Sulfate ratios indicated higher sensitivity to multiple administrations of testosterone undecanoate (TU) tablets and T gel, significantly prolonging detection times compared to conventional steroid profile biomarkers. Specifically, sulfate ratios such as androsterone sulfate (AS)/testosterone sulfate (TS) and epiandrosterone sulfate (EpiAS)/TS enabled detection for an average of 20 days following the last oral TU dose and at least 16 days after the last transdermal T application. These findings provide further evidence that incorporating sulfate EAAS metabolites into steroid profiling enhances detection capabilities. For advanced T doping detection, sulfate metabolites should be considered essential biomarkers in the steroid profile.