What is lipase?

What is Lipase?

Lipase is a digestive enzyme produced primarily by the pancreas that catalyzes the hydrolysis of triglycerides (fats) into fatty acids and glycerol, enabling fat absorption in the small intestine. 1, 2

Biochemical Characteristics

• Lipase is a glycoprotein containing 420-449 amino acid residues with a molecular weight of 46,000-56,000 for pancreatic lipase and 32,000-39,000 for serum lipase 1
• The enzyme contains a catalytic triad (Asp-His-Ser) where serine serves as the nucleophilic residue essential for catalysis 1
• Lipase differs from other esterases by possessing a hydrophobic recognition site that allows it to act specifically on water-insoluble lipid molecules 1, 2
• The optimal pH for lipase activity ranges between 7.5 and 10.0, depending on reaction conditions 1

Sources and Distribution

• While pancreatic lipase is the most clinically relevant, lipases are present in multiple tissues including the pancreas, intestines, stomach, liver, and various other organs 1, 2
• The concentration gradient between pancreatic tissue and serum is approximately 20,000-fold, making the pancreas the primary source 1
• The pancreatic lipase gene family consists of 7 mammalian subfamilies: pancreatic lipase, pancreatic lipase related proteins 1 and 2, hepatic lipase, lipoprotein lipase, endothelial lipase, and phosphatidylserine phospholipase A1 2

Physiological Function

• Pancreatic lipase is responsible for hydrolyzing over 80% of total dietary fats in the digestive system 3
• For optimal activity, lipase requires colipase (a water-soluble, heat-stable protein), secondary bile salts, and calcium ions 1
• In the capillary beds of adipose tissue and muscle, lipase hydrolyzes core triglycerides in chylomicrons and VLDL particles after activation by apolipoprotein CII 4
• The lipolytic products (free fatty acids) can be taken up by fat cells for storage or by muscle cells for energy production 4

Clinical Significance

• Serum lipase is the preferred diagnostic marker for acute pancreatitis, demonstrating superior sensitivity (79%) and specificity (89%) compared to amylase 4, 5, 6
• Lipase rises within 4-8 hours of pancreatic injury, peaks at 24 hours, and remains elevated for 8-14 days—providing a significantly larger diagnostic window than amylase (which normalizes in 3-7 days) 4, 6
• A diagnostic cutoff of >3 times the upper limit of normal provides the highest specificity for acute pancreatitis 6
• In chronic pancreatitis, lipase production may be significantly reduced due to pancreatic tissue destruction, potentially resulting in normal or only mildly elevated levels during acute exacerbations 5

Therapeutic Applications

• Pancreatic enzyme replacement therapy (PERT) containing lipase is used to treat exocrine pancreatic insufficiency, with initial dosing of at least 40,000 USP units of lipase during each meal in adults 4
• All FDA-approved PERT products are of porcine origin and labeled based on their USP lipase content 4
• Lipase inhibitors (such as orlistat) are used for obesity treatment by reducing fat absorption in the intestine 7, 3