Exocrine pancreatic insufficiency (EPI) is a condition characterized by deficiency of the exocrine pancreatic enzymes, resulting in the inability to digest food properly, or maldigestion. The etiology of this deficiency includes both pancreatic and nonpancreatic causes.
The exocrine pancreas produces 3 main types of enzymes—amylase, protease, and lipase. Under normal physiologic conditions, the enzymes (specifically, lipase) break undigested triglycerides into fatty acids and monoglycerides, which are then solubilized by bile salts (see Pathophysiology). Because the exocrine pancreas retains a large reserve capacity for enzyme secretion, fat digestion is not clearly impaired until lipase output decreases to below 10% of the normal level.
The diagnosis of exocrine pancreatic insufficiency (EPI) is largely clinical. It may go undetected because the signs and symptoms are similar to those of other gastrointestinal (GI) diseases or because the signs and symptoms are not always evident, owing to dietary restrictions.