UNCONJUGATED FECAL BILE-ACIDS IN FAMILIAL ADENOMATOUS POLYPOSIS ANALYZED BY GAS-LIQUID-CHROMATOGRAPHY AND MASS-SPECTROMETRY

Previous studies have suggested reduced formation of secondary bile acids in patients with familial adenomatous polyposis (FAP). Developments in the collection, extraction and analysis of faecal bile acids as well as in the accurate diagnosis of FAP by DNA markers prompted reinvestigation of this hypothesis. The median (interquartile range (i.q.r.)) faecal bile acid concentration (3.69 (1.66-5.36) pmol per g dry weight) and daily excretion rate (60.5 (29-149) mu mol per g per 24 h) in ten patients with FAP were similar to those of nine control subjects (3.31 (0.65-8.38) mu mol per g dry weight and 30.1 (7.9-228) mu mol per g per 24 h). Although the median (i.q.r.) concentration of only one bile acid (12-oxo-lithocholic acid) was significantly different between patients with FAP and controls (49 (34-70) versus 0 (0-20) nmol per g dry weight, P=0.006), the derivatives of chenodeoxycholic acid (3.35 (1.7-5.32) versus 0.51 (0.13-2.37) mu mol per g dry weight, P=0.02) and cholic acid (1.63 (0.42-2.34) versus 0.80 (0.13-3.57) mu mol per g dry weight, P=0.006) were increased in those with polyposis. These results show increased bacterial biotransformation of faecal bile acids in patients with FAP.