Pancreatic exocrine insufficiency beyond pancreatitis

Pancreatic exocrine insufficiency (PEI) occurs when the amount of digestive enzymes released from the pancreas in response to a meal is insufficient or the enzymes are prematurely inactivated, thus resulting in maldigestion. The chief reasons for PEI include loss of pancreatic parenchyma, obstruction of the main pancreatic duct, reduced stimulation and pancreatic enzyme inactivation. Loss of pancreatic parenchyma in chronic pancreatitis and after an episode of severe acute necrotizing pancreatitis are the most common causes for PEI. However, PEI is an important cause for malabsorption in many other diseases beyond pancreatitis. These include pancreatic tumors, pancreas resection, cystic fibrosis, diabetes and inflammatory bowel disease. Though the pancreas secretes lipase, amylase and proteases, which are all required for digestion, it is only lipase insufficiency that is clinically important. Fat maldigestion occurs when lipase secretion falls to below 10% of normal. This threshold is defined as severe PEI and is a definite indication for pancreatic enzyme replacement therapy (PERT). In this review, we shall discuss about conditions, other than pancreatitis, which cause PEI, and understand the possible mechanisms by which they cause PEI. We shall also discuss whether the addition of PERT will benefit patient management in such conditions.