Implementation of a marker substance for monitoring in situ 17-keto modifications in endogenous steroids caused by microbiological contamination.

Abstract

The urinary steroid profile established for the monitoring of eventual testosterone or testosterone precursor application by athletes includes concentrations and ratios of various endogenously produced steroidal hormones and metabolites. Due to enzymatic activities in urine specimens, the concentrations of these endogenous steroids and consequently their ratios may alter, leading to potential misinterpretation of analytical results. Microbiological contamination in athletes' urine samples can occur due to urinary tract infections or due to contamination by the non-sterile sample collection conditions. Depending on the duration of transportation of urine samples, the transport and storage conditions may favour microorganisms' growth, and therefore, the enzymatic activity can be accelerated. Degradation effects on endogenous steroids caused by microorganisms have been observed, such as hydrolysis of steroid conjugates, increase of testosterone in the free fraction or modification of the steroid structure by oxidoreductive reactions. The World Anti-Doping Agency (WADA) implemented criteria to check for signs of microbial degradation in a technical document dealing with the detection, analysis and reporting of endogenous androgenic anabolic steroids (TD EAAS) in urine samples. During the endogenous steroid profile confirmation procedures (CPs) of the WADA accredited Seibersdorf Laboratory, significant differences in the concentrations of markers of the steroid profile were observed compared to the initial testing procedures (ITPs). The changes in concentrations of the urinary steroid profile were attributed to the reduction of the 17-keto group to a 17β-hydroxy group caused by increased enzymatic activity during the hydrolysis step. In order to monitor the 17-keto reduction activity in athletes' urine specimens, possible marker substances containing a 17-keto group were synthesised and added in the internal standards mixture (ISTD) of the ITP. The presence of the reduced 17β-hydroxy form of the marker substance indicated enzymatic activity leading to 17-keto reduction reactions. The substance 3β-ethoxy-5α-androstane-17-one was defined to be suitable to indicate 17-keto reduction reactions occurring during hydrolysis carried out at moderate temperatures.