Inter‐individual variation of the urinary steroid profiles in Swedish and Norwegian athletes

The steroidal module of the Athlete Biological Passport (ABP) aims to detect doping with endogenous steroids, e.g. testosterone (T), by longitudinally monitoring several biomarkers. These biomarkers are ratios combined of urinary concentrations of testosterone and metabolically related steroids. However, it is evident after five years of monitoring steroid passports, that there are large variations in the steroid ratios complicating its interpretation. In this study, we used over 11 000 urinary steroid profiles from Swedish and Norwegian athletes to determine both the inter‐ and intra‐individual variations of all steroids and ratios in the steroidal passport. Furthermore, we investigated if…