19-Norandrosterone
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19-Norandrosterone, also known as 5α-estran-3α-ol-17-one, is a metabolite of nandrolone (19-nortestosterone) and bolandione (19-norandrostenedione) that is formed by 5α-reductase. It is on the list of substances prohibited by the World Anti-Doping Agency since it is a detectable metabolite of nandrolone, an anabolic-androgenic steroid (AAS).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Consumption of androstendione products contaminated with traces of bolandione may also result in testing positive for nandrolone.<ref>Template:Cite journal</ref>
Traces of 19-norandrosterone may be naturally present in human urine. An experiment conducted on athletes showed that after a prolonged intense effort, the 19-norandrosterone concentration can be increased by a factor varying between 2 and 4,<ref name="pmid10080643">Template:Cite journal</ref> but another study failed to replicate the result.<ref>Template:Cite journal</ref> Concentration also increases in the urine of female athletes during menstruation.<ref name="pmid11717005">Template:Cite journal</ref> The consumption of edible parts of a non-castrated pig, containing 19-nortestosterone, has been shown to result in the excretion of 19-norandrosterone in the following hours, so athletes should prudently avoid meals composed of pig offal in the hours preceding doping tests.<ref name="pmid16799098">Template:Cite journal</ref> Consumption of boar meat, liver, kidneys and heart also increased 19-norandrosterone output.<ref name="pmid10861987">Template:Cite journal</ref>