Lab Test: Amylase (Blood) Level
- A digestive enzyme mainly secreted by the pancreatitis as well as the salivary glands and is used to digest carbohydrates in the gastrointestinal (GI) tract.
- Can be used to detect and monitor the clinical course of pancreatitis and usually precedes the lipase. It is frequently ordered when a patient presents with acute abdominal pain (especially epigastric pain that is described as radiating to the back and associated with nausea and vomiting).
- Aids in evaluation for disorders of GI tract, autoimmune and viral illnesses, shock, trauma, and allergic reactions.
- Adults = 60-120 Somogyi units/dL or 30-220 units/L (SI units)
- Newborn = 6-65 units/L.
- Level remains low for the first two months of life and increases to adult values by the end of the first year of life.
- Values may be slightly increased during normal pregnancy and in older adults.
- Critical values: > 3 x the upper limit of normal (ULN; depending on the method).
- Suspected pancreatitis:
- Level > 4 times the ULN within 48 hours of onset of symptoms is highly suggestive of acute pancreatitis especially with the right clinical presentation. Levels peak within 24 to 36 hours and fall within 48 hours of illness onset.
- Patients with gallstone pancreatitis tend to have higher amylase levels than patients with alcoholic pancreatitis, but there is no distinct cutoff between the two.
- An elevation in serum amylase level greater than 4 times the ULN in a patient with symptoms (especially pain) following ERCP (usually within the first postoperative day) is diagnostic of post-ERCP pancreatitis.
- Suspected pancreatic injury in patients with blunt abdominal trauma.
- Hemolytic uremic syndrome
- Hemorrhagic shock
- Human immunodeficiency virus (HIV) infection:
- Asymptomatic pancreatic enzyme elevations (usually less than two fold) may occur in HIV patients.
- Usually associated with hepatitis B or C, or with certain medications.
- Known inflammatory bowel disease
- An elevated serum amylase level in a patient with aseptic meningitis should suggest mumps as the etiologic agent.
- Peptic ulcer (mainly with perforation)
- Ruptured ectopic pregnancy
- Suspected acute mesenteric ischemia:
- Levels greater than 600 units/L may indicate an extremely poor prognosis.
- Suspected cholescystitis:
- Levels are elevated in 15% tp 30% of patients with cholecystitis. Value may occasionally be greater than 1,000 units/dL, with or without concomitant pancreatitis.
- Suspected esophageal perforation:
- Level is generally normal in patients with esophageal perforation unless pancreatitis is the cause of vomiting.
- Toxic epidermal necrolysis:
- Hyperamylasemia (primarily salivary) is prominent in toxic epidermal necrolysis (TEN) and is associated with an increased risk of ocular sequelae. Could have predictive value of post-TEN Sjogren-like sicca syndrome.
- Amylase is normally secreted from pancreatic acinar cells into the pancreatic duct and then into the duodenum. Once in the intestine it aids in the catabolism of carbohydrates to their component simple sugars. Damage to pancreatic acinar cells causes an outpouring of this enzyme into the intrapancreatic lymph system and the free peritoneum. Blood vessels pick up the excess amylase.
- An abnormal rise in the serum level of amylase occurs within 12 hours of the onset of disease, but serum levels return to normal 48 to 72 hours after the initial insult.
- Persistent pancreatitis, duct obstruction, or pancreatic duct leak will cause persistent elevated amylase levels.
- Other nonpancreatic diseases can cause elevated levels, such as bowel perforation, penetrating peptic ulcer into the pancreas, duodenal obstruction, mumps, ectopic pregnancy and severe diabetic ketoacidosis.
- Urine amylase:
- Note: Amylase can be detected in the urine long after serum amylase has cleared.
- More specific for the pancreas
- Serum lipemia:
- May factitiously decrease amylase levels
- Intravenous dextrose solutions
- Can lower amylase levels and cause a false-negative result.
- Drugs that may cause increased serum levels:
- Aminosalicylic acid, aspirin, azathioprine, corticosteroids, dexamethasone, ethyl alcohol, glucocorticoids, iodine-containing contrast media, loop diuretics (e.g., furosemide), methyldopa, narcotic analgesics, oral contraceptives, and prednisone.
- Drugs that may cause decreased levels:
- Citrates, glucose, and oxalates.
- Collect a venous sample.
- Apply pressure or a pressure dressing to the venipuncture site and check the site for bleeding
- Explain the procedure to the patient and tell them that no fasting is required.
Indications & Uses
What To Tell Patient Before & After
MESH Terms & Keywords