Abstract des Autors

Urinary steroid profiles (steroid ratios) are used to control the misuse of endogenous steroids such as testosterone and dihydrotestosterone. For example, the testosterone/epitestosterone (T/E) ratio, measured by gas chromatography/mass spectrometry (GC/MS), is used to control testosterone administration. When the ratio lies outside the normal range (T/E > 6), the sample is positive (or a recommendation is made for a follow-up study). Similarly, dihydrotestosterone (DHT) misuse is controlled by comparing the ratios of the urinary excreted diols, 5alpha-androstane-3alpha,17beta-diol (5alphaAD) and 5beta-androstane-3alpha,17beta-diol (5betaAD). Recent investigations have illustrated the effectiveness of carbon isotope ratio mass spectrometry to detect and confirm testosterone administration. The method is based on comparison of the carbon isotope ratio (13C/12C) of testosterone to other endogenous steroids (testosterone precursors and metabolites). As exogenous (synthetic) testosterone has a lower 13C abundance, measurement of the urinary testosterone carbon isotope ratio can be used to prove testosterone misuse. In fact, the carbon isotope ratios can be used to determine testosterone administration even when the T/E ratio is at its normal value (T/E=1). With support from the International Cycling Federation we have been able to continue our preliminary investigations with testosterone and have developed a method for confirming testosterone misuse based on carbon isotope ratio mass spectrometry. The method is based on carbon isotope ratio measurements of testosterone, testosterone metabolites, androsterone, etiocholanolone, 5alphaAD and 5betaAD, and testosterone precursors, e.g., pregnanediol, pregnanetriol and cholesterol. In addition, we have expanded the existing procedure to detect misuse of other endogenous steroids, including dihydrotestosterone (DHT) and dehydroepiandrosterone (DHEA). Verf.-Referat