Amylase Blood Test is helpful when it comes to detecting and monitoring the clinical course of pancreatitis. It is frequently ordered when a patient presents with acute abdominal pain.The Amylase Blood Test, which is easy and rapidly performed, is most specific for pancreatitis. Pancreatic Acinar Cells normally secrete Amylase to the pancreatic duct, and from there Amylase travels the duodenum. Once in the intestine it aids in the catabolism of carbohydrates to their component simple sugars.
When pancreatic acinar cells are damaged (as in the case of pancreatitis) or the pancreatic duct flow is obstructed (as in the case of Pancreatic Carcinoma or common Bile Duct Gallstones), this causes leaking Amylase into the intrapancreatic lymph nodes and into the peritoneum. Blood vessels draining the free peritoneum and absorbing the lymph pick up the excess amylase. An abnormal rise in the serum level of amylase occurs within 12 hours of the onset of disease. Because amylase is rapidly cleared (2 hours) by the kidney, serum levels return to normal 48 to 72 hours after the initial insult. Persistent pancreatitis, duct obstruction, or pancreatic duct leak (e.g., pseudocysts) will cause persistent elevated serum amylase levels.
While the Blood Amylase Test targets pancreas diseases, it is not specific. High Blood Amylase levels can be caused by nonpancreatic conditions. For example, during bowel perforation, intraluminal amylase leaks into the free peritoneum and is picked up by the peritoneal blood vessels. This results in an elevated serum amylase level. A penetrating peptic ulcer into the pancreas will also cause elevated amylase levels. Duodenal obstruction can be associated with less significant elevations in amylase. Because salivary glands contain amylase, elevations can be expected in patients with parotiditis (mumps). Amylase is also found in low levels in the ovaries and skeletal muscles. Ectopic pregnancy and severe diabetic ketoacidosis are also associated with hyperamylasemia.
Patients with chronic pancreatic disorders (e.g., chronic pancreatitis) that have resulted in pancreatic cell destruction or patients with massive hemorrhagic pancreatic necrosis often do not have high amylase levels, because there may be so few pancreatic cells left to make amylase.
Normal Blood Amylase Levels
Adult: 30-220 international units/L.
Newborn: 6-65 international units/L.
Normal Blood Amylase Levels may be slightly increased during pregnancy and in older adults.
Causes of Blood Amylase Test False Results
- Serum Lipemia factitiously decreases amylase with the currently used laboratory methods.
- Intravenous dextrose solutions can lower amylase levels and cause a false-negative result.
- Drugs that may cause high blood amylase levels include 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 low Blood Amylase levels include Citrates, Glucose, and Oxalates.
Causes of High Blood Amylase Levels
- High Blood Amylase levels are associated with Acute Pancreatitis, and Chronic Relapsing Pancreatitis because damage to pancreatic acinar cells, as in pancreatitis, causes an outpouring of amylase into the intrapancreatic lymph system and the free peritoneum. Blood vessels draining the free peritoneum and absorbing the lymph pick up the excess amylase.
- Penetrating Peptic Ulcer into the pancreas: The peptic ulcer penetrates the posterior wall of the duodenum into the pancreas. This causes a localized pancreatitis with elevated amylase levels.
- Gastrointestinal Disease: In patients with perforated peptic ulcer, necrotic bowel, perforated bowel, or duodenal obstruction, amylase leaks out of the gut and into the free peritoneal cavity. The amylase is picked up by the blood and lymphatics of the peritoneum, where levels are demonstrated in excess.
- Amylase is also present in the salivary glands, gallbladder, and fallopian tubes. Situations affecting these organs will be associated with elevated levels of amylase.This includes Acute Cholecystitis, Parotiditis (Mumps), and Ruptured ectopic pregnancy.
- Renal failure: Amylase is cleared by the kidney. Renal diseases will reduce excretion of amylase.
- Diabetic Ketoacidosis.
- Pulmonary Infarction.
- After endoscopic retrograde Pancreatography.