German Sport University Cologne, Institute of Biochemistry, Am Sportpark Müngersdorf 6, Köln, Germany.
Drug Test Anal. 2009 Nov;1(11-12):576-86. doi: 10.1002/dta.53.
Epitestosterone (17alpha-hydroxy-androst-4-en-3-one, EpiT) belongs to the list of prohibited substances of the World Anti-Doping Agency (WADA). Although it possesses no anabolic effect, it is presumed to be misused by athletes in order to mask administration of testosterone (T) by lowering the urinary T/EpiT ratio.To improve detection, an excretion study with 40 mg of orally administered EpiT was conducted focusing on the metabolites of EpiT: 5alpha- and 5beta-androstane-3alpha,17 alpha-diol (5aEpiD and 5bEpiD). A reference population of n = 74 volunteers was investigated to elucidate the urinary concentrations of these steroids.In order to prove whether an unusual finding in urinary concentrations or ratios is due to an illicit intake of steroids or due to physiological elevation, determination of carbon isotope ratios is advisable. A method for isotope ratio determination was developed to enable (13)C/(12)C ratios of EpiT, 5bEpiD, 5aEpiD, pregnanediol and androsterone and etiocholanolone to be measured from a single urine specimen. The method's validity was tested by applying linear mixing models and specificity was ensured by means of gas chromatography/mass spectrometry analysis. delta(13)C values at natural levels were determined with a reference population and both Delta values and corresponding reference limits were calculated.Considering the implemented EpiT-metabolites, a more than twofold extension of the detection time of EpiT administration was achieved with both the urinary concentration thresholds and the (13)C/(12)C ratios.
表雄酮（17α-羟基雄甾-4-烯-3-酮，EpiT）属于世界反兴奋剂机构（WADA）禁用物质清单。尽管它没有合成代谢作用，但据推测，运动员会滥用它来通过降低尿中 T/EpiT 比值来掩盖睾酮（T）的使用。为了提高检测效果，进行了一项 40 毫克口服表雄酮排泄研究，重点研究了表雄酮的代谢物：5α-和 5β-雄烷-3α，17α-二醇（5aEpiD 和 5bEpiD）。调查了一个由 n = 74 名志愿者组成的参考人群，以阐明这些类固醇在尿液中的浓度。为了证明尿液浓度或比值的异常发现是由于非法摄入类固醇还是由于生理升高，建议测定碳同位素比值。开发了一种同位素比测定方法，能够从单个尿样中测定表雄酮、5bEpiD、5aEpiD、孕烷二醇和雄酮和雄烯二酮的（13）C/（12）C 比值。通过应用线性混合模型测试了该方法的有效性，并通过气相色谱/质谱分析确保了特异性。用参考人群确定了天然水平的 δ（13）C 值，并计算了 Delta 值和相应的参考限值。考虑到实施的 EpiT 代谢物，与仅使用尿液浓度阈值相比，EpiT 给药的检测时间延长了两倍以上，同时也使用了（13）C/（12）C 比值。
