Effectiveness of blood steroidal passport markers for detecting testosterone abuse in Asians

The World Anti-Doping Agency (WADA) has introduced an Athlete Biological Passport (ABP) with a steroidal module, which is intended for the monitoring of longitudinal profiles of an athlete's steroid variables in urine to identify endogenous anabolic androgenic steroids that are administered exogenously. It has been in use since 2014. The prevalence of UGT2B17 gene deletion with relatively low levels of testosterone (T) glucuronide in urine is high in the Asian region. There are cases in which urinary T is below the detection limit in specific urine samples, for example, diluted urine, urine collected from females, or urine collected from UGT2B17 deletion individuals. Additional steroid markers T, 4-androstenedione (A4), and the T/A4 ratio in serum were newly added to the ABP steroidal module by WADA in 2023 to compensate for the urine steroid profile. In this study, populations of blood steroid markers in Asians (n = 510) were investigated and classified according to UGT2B17 polymorphism to confirm the effectiveness of blood steroid markers in monitoring Asian athletes. No significant difference in the T/A4 ratio was observed between the genotypes. Furthermore, an administration study of T enanthate in females (n = 10) who were classified according to UGT2B17 genotypes was performed. The concentration of T and the T/A4 ratio were found to be significantly increased in all post-administration samples until 15 days after administration (p < 0.01). The overall results supported the high effectiveness of subject-based monitoring for serum T and T/A4 ratio for recently identified shortcomings in the detection of T abuse in Asians.