Studies of serum and feces bile acids determination by gas chromatography-mass spectrometry.

Both radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) methods are utilized in the clinical laboratory to measure bile acids in human body fluids. For a more detailed analysis, we attempted simultaneous analysis of serum and feces bile acids using gas chromatography-mass spectrometry (GC-MS) and also investigated the dynamics of bile acids. Serum bile acid composition was examined in 22 healthy adults (79.9 +/- 6.0 years) and 20 colon cancer patients (65.1 +/- 9.5 years). Feces bile acid composition was examined in 20 healthy adults (50.7 +/- 7.6 years) and 20 colon cancer patients (63.6 +/- 8.5 years). The significance of differences was examined by Student's t-test. In both healthy adults and colon cancer patients, the bile acids detected in serum were cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), lithocholic acid (LCA), ursodeoxycholic acid (UDCA), and hyocholic acid (HCA). The following 12 bile acids were detected in feces: CA, allo CA, CDCA, allo CDCA, DCA, allo DCA, LCA, allo LCA, UDCA, HCA, UCA, and CA-6alpha-ol. For allo CA and allo CDCA, no significant differences were observed between the control group and the colon cancer patients. On the other hand, the concentration of allo LCA tended to be higher in the patients (p < 0.05), and the concentration of allo DCA was distinctly higher (p < 0.001) in the colon cancer group, particularly in men. The GC-MS method demonstrated bile acids undetectable by conventional RIA and ELISA. The dynamics suggested association of allo bile acids (DCA and LCA) with colon cancer.