Extrapancreatic Lipases and Its Influence on Pancreatic Lipase Assays

Presentation Description / Summary:
Lipases are water-soluble enzymes that hydrolyze water-insoluble lipid molecules, such as triglycerides, phospholipids, galactolipids, and cholesterol esters. The pancreatic lipase gene family is one of the best characterized lipase gene families and consists of 7 mammalian subfamilies including pancreatic lipase and its related proteins, hepatic lipase, and lipoprotein lipase. These lipases are grouped into this gene family due to its homology in amino acid, gene organization, and common three-dimensional structures. Other mammalian lipases that play important roles in lipid digestion but that are not within this gene family include carboxyl ester lipase and gastric lipase. Most enzymes have preferred substrate specificity, but much overlap occurs because of the similarities in their structures. While pancreatic lipase, carboxyl ester lipase, and gastric lipase are present in the circulatory system, they exert their role in lipid digestion within the intestinal lumen. In contrast, the major lipases for lipid metabolism in the circulatory system are hepatic lipase, lipoprotein lipase, and endothelial lipase. Under physiologic conditions, majority of pancreatic lipase is released into the intestinal lumen for lipid digestion. Less than 1% diffuses through the basolateral aspect of the pancreatic acinar into the circulation. In pancreatitis, a large amount of pancreatic lipase is released into circulation through the basolateral aspect. Therefore, the measurement of pancreatic lipase is useful as a non-invasive diagnostic marker for pancreatitis. In a clinical setting, the two most common methods to measure serum lipase are immunological and catalytic lipase assays. Accurate measurement of pancreatic lipase (and not just serum lipase) is important for the diagnosis of acute pancreatitis in dogs. In this session, we will explore the effects of extrapancreatic lipases on commonly available lipase assays.

Learner Outcomes: 
1. Introduction of the pancreatic lipase gene family
2. Commonly used serum lipase assays and its limitations