Nordeoxycholic acid is a metabolite of the bile acid norcholic acid and a 23-carbon derivative of deoxycholic acid .¹Levels of nordeoxycholic acid are decreased in the liver of rats in a high-fat diet model of non-alcoholic fatty liver disease (NAFLD) and serum levels are lower in men compared with women.^2,3Nordeoxycholic acid has commonly been used as an internal standard for the quantification of bile acids in various sample types by GC- and LC-MS.^4,5

1.Nakatomi, F., Kihira, K., Kuramoto, T., et al.Intestinal absorption and metabolism of norcholic acid in ratsJ. Pharmacobiodyn8(7)557-563(1985) 2.Tang, Y., Zhang, J., Li, J., et al.Turnover of bile acids in liver, serum and caecal content by high-fat diet feeding affects hepatic steatosis in ratsBiochim. Biophys. Acta Mol. Cell Biol. Lipids1864(10)1293-1304(2019) 3.Xie, G., Wang, Y., Wang, X., et al.Profiling of serum bile acids in a healthy Chinese population using UPLC-MS/MSJ. Proteome Res.14(2)850-859(2015) 4.Bergeron, A., Furtado, M., and Garofolo, F.Importance of using highly pure internal standards for successful liquid chromatography/tandem mass spectrometric bioanalytical assaysRapid Commun. Mass Spectrom.23(9)1287-1197(2009) 5.Evrard, E., and Janssen, G.Gas-liquid chromatographic determination of human fecal bile acidsJ. Lipid Res.9(2)226-236(1968)