对于反兴奋剂实验室,尿样中的非法睾酮(T)给药的确定仍然是一个困难的过程,因为它需要通过睾酮及其代谢物的碳同位素比(CIR)来确定外源来源.作为尿路分析的补充,通过液相色谱与串联质谱联用(LC-MS/MS)靶向血清样品中的睾酮酯(例如睾酮十一烷酸酯[TU])可以代表与同位素比质谱(IRMS)相比更简单的方法。这两种方法均导致直接检测外源性T的施用,但在分析的努力和复杂性方面存在差异。要将获得的检测窗口与两种策略进行比较,分析了从口服TU给药研究中收集的血清和相应的尿液样本。结果表明,在血清中检测到完整TU的所有时间点,尿类固醇的CIRs也与内源性来源不一致。IRMS分析需要更多的努力,但导致比酯分析稍长的检测窗口。最后,这项比较研究表明,在有可疑的泌尿类固醇的情况下,相应血清样品中的LC-MS/MS类固醇酯分析可能非常有帮助。如果没有检测到类固醇酯,然后可以对尿液样本进行IRMS分析。总的来说,矩阵的组合可能有助于检测体育运动中禁止的T给药,特别是对于具有自然低T/E比的运动员。
For antidoping laboratories, the determination of an illicit testosterone (T) administration in urine samples remains a difficult process as it requires the determination of the exogenous origin by carbon isotope ratios (CIRs) of testosterone and its metabolites. As a complement to the urinary analysis, targeting testosterone esters (e.g. testosterone undecanoate [TU]) in serum samples by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) could represent a simpler approach compared with isotope ratio mass spectrometry (IRMS). These two approaches both lead to the direct detection of the administration of exogenous T but with a difference in effort and complexity of the analysis. To compare the detection window obtained with the two strategies, serum and the corresponding urine samples collected from an administration study with oral TU were analysed. Results showed that, at all timepoints where the intact TU was detected in serum, the CIRs of urinary steroids were also not in agreement with an endogenous origin. IRMS analysis required more effort but resulted in slightly longer detection windows than the ester analysis. Finally, this comparison study showed that, in the presence of a suspicious urinary steroid profile, the LC-MS/MS steroid esters analysis in the corresponding serum samples can be very helpful. If steroid esters are not detected, the IRMS analysis can then be conducted on the urine sample afterwards. Overall, the combination of matrices might facilitate the detection of prohibited T administration in sports, especially for athletes with naturally low T/E ratios.