Bile acid sequestration by the solid phase of stools in cystic fibrosis patients. Role of pancreatic enzymes.

The distribution of bile acids in the stool of seven cystic fibrosis (CF) patients with severe or mild steatorrhea was examined and compared with that of three controls. Results indicated significantly lower endogenous bile acid concentrations in the stool water phase, obtained by centrifugation, in the CF patients (12.0 +/- 3.5%), compared with the controls (25.5 +/- 8.1%). In vitro incorporation of labeled cholic acid (CA) and deoxycholic acid (DCA) demonstrated a stronger binding of both to the particulate matter of stools in the CF group. Using equilibrium dialysis, the calculated concentrations of unbound CA and DCA in the CF group measured 0.78 and 0.3 mumol/g homogenate, respectively, and in the control patients 1.76 and 1.39 mumol/g homogenate, respectively. Partial release of bile acids from CF stool pellets was achieved by the addition of trypsin and elastase, as well as by alkalinization. It is suggested that in patients with CF, stool bile acids are bound to the undigested protein fraction, which makes them unavailable for colonic resorption.