Lipase is an enzyme produced primarily by the pancreatic acinar cells that is secreted into the small intestine to digest dietary fats. A small amount enters the bloodstream under normal circumstances, but significant pancreatic injury or inflammation causes lipase to be released in large quantities into the blood, making it the most sensitive and specific blood marker for acute pancreatitis.

Lipase has largely replaced amylase as the preferred test for pancreatitis in Australian and international emergency settings, as it remains elevated for longer after an acute episode (3-5 days for amylase versus 7-14 days for lipase) and is more specific for pancreatic rather than non-pancreatic sources. Markedly elevated lipase (more than 3x upper limit of normal) is highly specific for acute pancreatitis.