Serum amylase and lipase are common tests obtained as biochemical markers for acute pancreatitis. However, the interpretation of these tests can be difficult since several non-pancreatic conditions can present with abnormal serum amylase and lipase levels [1,2]. In addition, some patients with pancreatitis have normal serum amylase and lipase levels when a blood sample is examined [3,4]. (See "Clinical manifestations and diagnosis of acute pancreatitis".)
Several factors can influence serum amylase and lipase levels.
- The levels depend upon the rate of production from different tissues and the rate of clearance. As an example, serum amylase and lipase levels may be elevated in patients with renal failure. (See "Serum enzymes in patients with renal failure".)
- Organs other than the pancreas can produce these enzymes. Alcoholics, for example, may have an elevated serum amylase of salivary origin. The most commonly used amylase assays cannot differentiate between salivary and pancreatic amylase.
- Certain serum factors influence amylase and lipase enzyme activity. As an example, patients with pancreatitis due to hypertriglyceridemia may appear to have normal amylase levels, most likely due to a circulating factor that inhibits the enzyme's activity .
This topic review will present an approach the patient with an elevated serum amylase or lipase. Elevation of these measures in the context of individual disorders (such as pancreatitis) is discussed separately. (See "Clinical manifestations and diagnosis of acute pancreatitis", section on 'Pancreatic enzymes and products'.)
Amylase is derived from the Greek word "amylone," which means starch. The main sources of amylase in humans are the pancreas and salivary glands, but it can be found in other tissues in small quantities . The main function of amylase is to cleave starch into smaller polysaccharides at the internal 1 to 4 alpha linkage in the process of digestion.