δC13-Values of endogenous urinary steroids

By means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) urinary steroids obtained from a reference population of 56 subjects were analyzed for their C13/C12-ratios. The analytes encompassed androsterone (A), etiocholanolone (E), 11β-hydroxyetiocholanolone (OHE), 11β-hydroxyandrosterone (OHA), and 5β-pregnane- 3α,20α-diol (PD). A and E represent androgen metabolites (AM). PD, OHE, and OHA have sources independent from androgen metabolism. The δC13-values of the latter compounds may be compared to those of AM in order to detect doping with synthetic androgens and thus may serve as endogenous reference compounds (ERC). In order to allow for classification of conspicuous samples, reference ranges and limits were calculated for δC13-values of selected steroids and differences hereof (ΔC13-values). When A is compared to ERCs, ΔC13-values larger than 3‰‰ are very unlikely. A set of additional parameters was surveyed by a questionnaire. Several factors turned out to exert significant influence on the δC13-values of urin ary steroids. These encompass the identity of the steroid itself, sex, oral contraception, travels, and physical activity.