Nandrolone and its prohormones, including 19-norandrost-4-ene-3,17-dione and 19-norandrost-4-ene-3β,17β-diol, are anabolic steroids forbidden at all times in sports according to the World Anti-Doping Code Prohibited List and its metabolite 19-norandrosterone (19NA) is the preferred urinary target compound to identify their abuse. In recent years, an increasing number of 19NA isotope ratio mass spectrometry (IRMS) cases have arisen that, based on the initial testing procedure, were likely to result in an adverse analytical finding but were concluded negative after IRMS analysis. The current study was therefore set up to gain a better insight on the prevalence of nandrolone preparations with endogenous carbon isotope ratio values in Australia. Suitable workplace (non-athlete) urine samples that had previously been reported positive for 19NA were identified and analysed on IRMS. A total of 82% of the samples that were analysed were reported with enriched carbon isotope ratios of 19NA (i.e., 19NA greater than −26‰). This indicates that there is a high prevalence of nandrolone-containing anabolic androgenic steroid preparations in Australia that have ‘endogenous’ carbon isotope ratios which reduces the ability to identify exogenous nandrolone.

中文翻译：

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澳大利亚内源碳同位素比诺龙制剂的流行情况

根据世界反兴奋剂组织的规定，诺龙及其激素原，包括 19-norandrost-4-ene-3,17-dione 和 19-norandrost-4-ene-3β,17β-diol，都是体育运动中禁止使用的合成代谢类固醇。代码禁用清单及其代谢物 19-去甲雄酮 (19NA) 是识别其滥用情况的首选尿液目标化合物。近年来，越来越多的 19NA 同位素比质谱 (IRMS) 案例出现，根据最初的测试程序，可能会产生不利的分析结果，但在 IRMS 分析后得出阴性结论。因此，本研究的目的是为了更好地了解澳大利亚具有内源碳同位素比值的诺龙制剂的流行情况。之前报告 19NA 呈阳性的合适工作场所（非运动员）尿液样本在 IRMS 上进行了鉴定和分析。据报告，总共 82% 的分析样品的 19NA 富集碳同位素比率（即 19NA 大于 -26‰）。这表明在澳大利亚含有诺龙的合成代谢雄激素类固醇制剂的流行率很高，这些制剂具有“内源性”碳同位素比率，从而降低了识别外源诺龙的能力。