Pathogenesis of Steatorrhea in Primary Biliary Cirrhosis

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Abstract
To investigate the pathophysiology of steatorrhea in primary biliary cirrhosis, the severity of steatorrhea, small bowel histology and function, cholestasis, exocrine pancreatic secretion and liver histology were studied. Twenty–four primary biliary cirrhotic patients had a quantitative stool fat collection, serum bilirubin and alkaline phosphatase and liver biopsies. From this group, ten had further studies: a small bowel biopsy (n = 7); a D–xylose test (n = 9); measurement of pancreatiobiliary concentrations and outputs after intravenous cholecystokinin (n = 10); essential amino acid perfusion of the duodenum (n = 9), and eating a test meal (n = 7). D–xylose absorption was normal, and only one patient had a minimal small bowel mucosal abnormality. Pancreatic lipase outputs in response to cholecystokinin were low in two primary biliary cirrhotic patients, but were greater than 10% of normal. Postprandial lipase outputs were normal except in one patient who had abnormal duodenal acidification. Mean enzyme outputs in primary biliary cirrhotic patients were normal in response to essential amino acid perfusion; but 6 had low lipase and 5 had low trypsin outputs which were associated with decreased bile acid outputs (p < 0.03). Severity of steatorrhea was associated with reduced bile acid outputs and concentrations (r = 0.82; p < 0.0001), degree of cholestasis (serum bilirubin; r = 0.88; p < 0.001) and advanced histologic stages (p < 0.005). Severe intraluminal bile acid deficiency combined with a submaximal intraluminal stimulus (essential amino acids) may be associated with decreased exocrine pancreatic secretion in primary biliary cirrhosis. However, mild and severe steatorrhea is explained by severely reduced intraluminal bile acid content rather than decreased lipase secretion.