Etiology

1. Conditions leading to exocrine pancreatic insufficiency (EPI) due to chronic pancreatitis, cystic fibrosis (CF), and conditions resulting in pancreatic duct obstruction or resection of the pancreas (e.g., pancreatic tumors), and conditions leading to inactivation of lipase (Zollinger-Ellison syndrome)
2. Bile acid deficiency either due to cholestasis e.g. primary biliary cirrhosis, currently referred to as primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), or inability to absorb bile acids in the distal ileum resulting in diminished bile acid pool e.g. ileal resection or Crohn disease of the ileum or deconjugation of bile acids e.g., small intestinal bacterial overgrowth (SIBO)
3. Diseases affecting proximal small intestines such as celiac disease, tropical sprue, giardiasis, Whipple disease, lymphoma, amyloidosis, SIBO, and HIV enteropathy