Fat digestion and exocrine pancreatic function in primary biliary cirrhosis

Intestinal bile salt deficiency marginally impairs fat absorption in cholestatic patients. The finding of massive steatorrhea in some patients with primary biliary cirrhosis led us to systematically study and compare fat digestion in control subjects (n = 4) and patients with biliary cirrhosis with (n = 11) and without (n = 3) steatorrhea. The jejunum was anatomically and functionally intact in all subjects, as demonstrated by normal gastrointestinal radiology and xylose absorption, respectively. The intestinal contents were recovered during digestion of a fat meal. Lipolysis, pH, and trypsin activity were measured in whole intestinal contents, whereas bile salts, total lipid, and fatty acid were determined in both total and aqueous phases. The results obtained in controls and patients without steatorrhea were similar. Percentage of lipolysis and intraluminal pH were normal in controls and in both patient groups. The intestinal contents of the patients with steatorrhea had a significantly lesser capacity to solubilize both total lipid and fatty acid in relation to abnormally low aqueous bile salt concentrations. No bile salt deconjugation and only minimal bile salt precipitation were found, thus low aqueous bile salts were strictly related to bile secretory failure. Steatorrhea was always present when aqueous bile salt levels were below 3.0 mM. Intestinal trypsin activity was subnormal in patients with steatorrhea; decreased trypsin activity was related (r = 0.82, p less than 0.001) to reduced intestinal bile salt levels. One patient was found to have severe exocrine pancreatic failure. Administration of medium chain triglycerides was uniformly effective in improving nutrition in patients with steatorrhea, but the course of the disease was unaffected. These results indicate that overt pancreatic failure is uncommon in primary biliary cirrhosis, and that fat maldigestion and steatorrhea, regardless of what degree, are due mainly to low intestinal bile salt levels secondary to bile secretory failure. Finally, subnormal pancreatic function in this disease appears to be related to the bile secretory failure, suggesting either that the lack of bile or bile salts in the intestine depresses pancreatic exocrine function or that both biliary and pancreatic secretions decrease in parallel as part of a widespread secretory failure syndrome.