Recently the use of high resolution mass spectrometry or tandem mass spectrometry has enabled the detection of low amounts of anabolic steroids. As a consequence, the post-administration detection time of these drugs has been extended. Recent investigations have shown that norandrosterone, previously unequivocally regarded as evidence of nandrolone administration, might be an endogenous steroid present in small amounts in urine of humans. In this study, very low concentrations (<1 ng/ml) of norandrosterone in urine of a female athlete were detected using tandem mass spectrometry. The presence of norandrosterone was strongly correlated with high plasma 17β-estradiol levels during the menstrual cycle. Analysis of urine samples from pregnant women supports the hypothesis of formation of precursors for urinary 19-norandrosterone during aromatization of androgens to estrogens. The detection of low urinary concentrations of norandrosterone (0.2-0.5 ng/ml) in samples after strenuous exercise could be regarded as an additional evidence for the existence of such a pathway.

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Keywords Endogenous, Estradiol, Female, Nandrolone, Norandrosterone
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Journal The Journal of Steroid Biochemistry and Molecular Biology
van Eenoo, P, Delbeke, L, de Jong, F.H, & de Backer, P. (2001). Endogenous origin of norandrosterone in female urine: Indirect evidence for the production of 19-norsteroids as by-products in the conversion from androgen to estrogen. The Journal of Steroid Biochemistry and Molecular Biology, 78(4), 351–357. doi:10.1016/S0960-0760(01)00112-1