Amylase is a digestive enzyme that splits starch into disaccharides such as maltose. Although many cells have amylase activity (e.g., liver, small intestine, skeletal muscle, fallopian tubes), amylase circulating in normal serum derives from the parotid glands and the pancreas. Unlike many other enzymes, amylase activity is primarily extracellular; it is secreted into saliva and the duodenum, where it splits large carbohydrate molecules into smaller units for further digestive action by intestinal enzymes.

Elevations in serum amylase are generally seen in pancreatic inflammations, which cause disruption of pancreatic cells and absorption of the extracellular enzyme from the intestine and peritoneal lymphatics. Serum amylase levels also rise sharply after administration of drugs that constrict pancreatic duct sphincters. The most common offender is morphine, and this drug is never indicated for individuals with abdominal pain that could be of pancreatic or biliary tract origin. Other drugs that may produce elevated serum amylase levels are codeine, chlorothiazides, aspirin, pentazocine, corticosteroids, oral contraceptives, pancreozymin, and secretin. Specific causes of elevated serum amylase, and the magnitude of the elevations produced, are listed in Table 5-19.

Note: Values may vary according to the laboratory performing the test.

• A number of drugs may produce elevated levels (e.g., morphine, codeine, chlorothiazides, aspirin, pentazocine, corticosteroids, oral contraceptives, pancreozymin, and secretin).
• High blood glucose levels, which may be a result of diabetes mellitus or IV glucose solutions, can lead to decreased levels.

• Diagnosis of early acute pancreatitis:
  • Serum amylase begins rising within 6 to 24 hours after onset and returns to normal in 2 to 7 days.
  • Urine amylase levels may remain elevated for several days after serum amylase levels return to normal.
• Detection of blunt trauma or inadvertent surgical trauma to the pancreas as indicated by elevated levels
• Diagnosis of macroamylasemia, a disorder seen in alcoholism, malabsorption syndrome, and other digestive problems with circulating complexes of amylase and high-molecular-weight dextran (findings include high serum amylase and negative urine amylase)
• Support for diagnosing other disorders associated with elevated serum amylase levels (see Table 5-19)
• Support for diagnosing disorders associated with decreased amylase levels, such as advanced chronic pancreatitis, advanced cystic fibrosis, liver disease, liver abscess, toxemia of pregnancy, severe burns, and cholecystitis

Nursing Care Before the Procedure

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

• Because many drugs may alter serum amylase levels, a medication history should be obtained. It is recommended that any 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 any drugs withheld before the test, pending test results.
• Abnormal values: Note and report increased levels. Correlate with urine amylase, hypocalcemia, hypokalemia, hyperglycemia, and bilirubin in relation to pancreatic diseases. Assess for fluid deficit if pancreatic hemorrhage is present, severity of abdominal pain if acute inflammation is present, jaundice if common bile duct is obstructed, and bowel sounds. Maintain nothing by mouth (NPO) status and prepare client for IV fluids, nasogastric tube (NG) insertion, and bowel decompression to decrease pancreatic stimulation. Instruct client to avoid alcohol intake and to reduce carbohydrate intake if absorption problem exists.