Amylase, Serum

Test Description

Amylase is an enzyme found primarily in the pancreas and salivary glands and in

minor amounts in the liver and fallopian tubes. Its function is to assist in the digestion

of complex carbohydrates into simple sugars. Measurement of serum amylase is

often performed to differentiate abdominal pain due to acute pancreatitis from other

causes of abdominal pain that may require surgical treatment. The serum amylase

begins to rise 3 to 6 hours after the onset of acute pancreatitis and peaks in approximately

24 hours. The values return to normal within 2 to 3 days after onset.

THE EVIDENCE FOR PRACTICE

Acute pancreatitis is suspected in patients presenting with epigastric upper abdominal pain that

is acute in onset, rapidly increasing in severity, and persistent without relief. Serum amylase

and/or lipase levels can be considered diagnostic when the reported value(s) is >3 times normal.

Normal Values

Adult: 53–123 U/L (0.88–2.05 nkat/L SI units)

Elderly: Slightly higher norms

Possible Meanings of Abnormal Values

Increased                                                                                    Decreased                          

Acute pancreatitis                                                                     Cirrhosis of liver

Alcoholism                                                                                Hepatitis

Biliary obstruction                                                                     Pancreatic cancer

Cholelithiasis                                                                             Severe burns

Diabetic ketoacidosis                                                                 Severe thyrotoxicosis

Hyperlipidemia

Hyperthyroidism

Inflammation of salivary glands

Mumps

Perforated bowel

Perforated peptic ulcer

Pregnancy

Ruptured tubal pregnancy

Contributing Factors to Abnormal Values

• Hemolysis of the blood sample will alter test results.

• Contamination of the sample with saliva by talking over an uncovered blood sample

  may falsely increase test results.

• Drugs that may increase serum amylase levels: acetaminophen, antibiotics, aspirin,

   corticosteroids, estrogens, furosemide, NSAIDs, prednisone, salicylates, and thiazide

   diuretics.

• Drugs that may decrease serum amylase levels: citrates, glucose, oxalates.

Interventions/Implications 

Pretest

• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.

• No fasting is required before the test.

  Procedure

• A 7-mL blood sample is drawn in a red-top collection tube.

• Gloves are worn throughout the procedure.

Post test

• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued

  bleeding.

• Label the specimen and transport it to the laboratory.

• Report abnormal findings to the primary care provider.

Clinical Alert                                                                                                                         

• Serum amylase and lipase are typically both evaluated in suspected pancreatitis.

• In some patients, acute pancreatitis may be present in the absence of enzyme

   abnormalities.