Rapid and quantitative analysis of unconjugated C(27) bile acids in plasma and blood samples by tandem mass spectrometry.

A subgroup of peroxisomal disorders, peroxisome biogenesis defects (PBD), can be differentiated by elevated levels of C(27) bile acids in plasma and bile. Patients with peroxisomal disorders, who lack the ability to chain-shorten the C(27) bile acid intermediates into C(24) bile acids, show elevated levels of C(27) bile acids, notably 3 alpha,7 alpha-dihydroxy-5 beta-cholest-26-oic acid and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid. C(27) bile acids are normally estimated against other bile acid standards, by time-consuming gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry methods, in plasma (minimum of 50 microl). In this article we describe the quantitation of unconjugated di- and trihydroxy C(27) bile acids in 5-microl plasma samples and 3-mm blood spots, using deuterium-labeled internal standards. The synthesis of (2)H(3)-labeled di- and trihydroxycoprostanic acids is described. The sample preparation and analysis by electrospray tandem mass spectrometry (ES-MS/MS) takes less than 1 h and features dimethylaminoethyl ester derivatives. The levels of the di- and trihydroxy bile acids are significantly higher in PBD patients than in age-matched control subjects for both plasma and blood spots collected at birth (some stored for up to 18 years). Excellent correlation is observed between the C(26:0)/C(22:0) very long chain fatty acid (VLCFA) ratio and the levels of trihydroxy C(27) bile acids in plasma from PBD patients. The ES-MS/MS method can be used to rapidly screen for PBD patients in plasma samples with elevated C(26:0)/C(22:0) VLCFA ratios and in archived collections of neonatal blood spots. - Johnson, D. W., H. J. ten Brink, R. C. Schuit, and C. Jakobs. Rapid and quantitative analysis of unconjugated C(27) bile acids in plasma and blood samples by tandem mass spectrometry. J. Lipid Res. 2001. 42: 9;-16.