Lipases split triglycerides into fatty acids and glycerol. Different lipolytic enzymes have different specific substrates, but overall activity is collectively described as lipase. Serum lipase derives primarily from pancreatic lipase, which is secreted into the duodenum and participates in fat digestion. Pancreatic lipase is quite distinct from lipoprotein lipases, which clear the blood of chylomicrons after fats are absorbed.

Viral hepatitis and disorders in which bile salts are decreased may produce low serum lipase levels, as will protamine and IV infusions of saline.

• Morphine, cholinergic drugs, and heparin may lead to elevated levels.
• Protamine and IV infusions of saline may lead to decreased levels.

• Diagnosis of acute pancreatitis, especially if the client has been ill for more than 3 days:
  • Serum amylase levels may return to normal after 3 days, but serum lipase remains elevated for approximately 10 days after onset.
• Support for diagnosing pancreatic carcinoma, especially if there is a sustained moderate elevation in serum lipase levels
• Support for diagnosing other disorders associated with elevated serum lipase levels (e.g., peptic ulcer, acute cholecystitis, and early renal failure)
• Support for diagnosing disorders associated with decreased serum lipase levels (e.g., advanced chronic pancreatitis, cystic fibrosis, advanced carcinoma of the pancreas, and viral hepatitis)

Nursing Care Before the Procedure

Client preparation is the same as that for any test involving collection of a peripheral blood sample (see Appendix I).

• The client should fast from food for at least 8 hours before the test.
• It is recommended that drugs that may alter test results be withheld for 12 to 24 hours before the test, although this practice should be confirmed with the person ordering the study.

A venipuncture is performed and the sample collected in a red-topped tube. The sample should be handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Resume food and any drugs withheld before the test.