Lipase

Lipase, more specifically pancreatic lipase, is an enzyme produced in the pancreas and is responsible for the digestion of fat molecules. It may be raised in numerous pancreatic, hepatobilary and other diseases but is most commonly associated with acute pancreatitis.

Physiological basis

Lipases catalyse the reaction of triglycerides into glycerol and fatty acid molecules. Production occurs in the acinar cells of the pancreas, lipase is stored in the zymogen granules before being released via the pancreatic duct and the ampulla into the duodenum where it begins to act on fats ¹. Lipases are also produced and found in the stomach, duodenum and salivary glands albeit in much smaller amounts.

It is also detectable in the serum at roughly 20,000 times less concentration than the pancreas, giving it great clinical use ¹. The normal range of lipase varies with age and the analytical technique used in the laboratory, but is somewhere between 8-78 international units per litre ³.

Interpretation

A significant elevation is generally regarded as three times the upper limit of normal ³.

Lipase is the preferred enzyme to measure during acute pancreatitis and is regarded as being superior to amylase as it more sensitive and has a longer half-life ². Although lipase is useful in diagnosing acute pancreatitis levels do not correspond to the risk of complications or clinical severity ².

A brief list of possible causes of elevation is provided below ⁴:

Significant elevation

Pancreatic conditions

• Acute pancreatitis
• Acute on chronic pancreatitis
• Post ERCP
• Pancreatic tumours

Intra-abdominal non-pancreatic conditions

• Gastric perforation
• Bowel perforation
• Bowel obstruction
• Peptic ulcer disease
• Ruptured abdominal aortic aneurysm
• Biliary atresia
• Cholecystitis

Reduced clearance

• Macrolipase (essentially a very large lipase molecule)
• Renal impairment (either acute or chronic)

Other conditions

• Drug related (e.g. chronic alcoholism)
• Diabetic ketoacidosis
• Neurosurgery