Amylase test

Definition 
A test to measure the amount of amylase in serum (blood).

How the test is performed 
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood).

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test 
There is no special preparation. However, you should avoid alcohol before the test. The health care provider may advise you to withhold drugs that may affect the test.

Drugs that can increase amylase measurements include asparaginase, aspirin, cholinergic agents, corticosteroids, indomethacin, loop and thiazide diuretics, methyldopa, opiates (codeine, morphine), oral contraceptives (birth control pills), and pentazocine.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

How the test will feel 
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed 

This test is primarily performed to diagnose or monitor diseases of the pancreas. It may also reflect some gastrointestinal problems.

Amylase is an enzyme that helps digest glycogen and starch. It is produced mainly in the salivary glands and pancreas. When the pancreas is diseased or inflamed, amylase escapes into the blood.

Normal Values
 
The normal range is 23 to 85 U/L. Some laboratories give a range of 40 to 140 U/L.

Note: U/L = units per liter

What abnormal results mean
 
Increased amylase levels may indicate:

     
  • acute pancreatitis  
  • cancer of the pancreas, ovaries, or lungs  
  • cholecystitis  
  • ectopic or ruptured tubal pregnancy  
  • gallbladder attack resulting from disease  
  • infection of the salivary glands (Mumps or an obstruction)  
  • intestinal obstruction  
  • macroamylasemia  
  • pancreatic or bile duct obstruction  
  • perforated ulcer

Decreased amylase levels may indicate:

     
  • damage to the pancreas  
  • kidney disease  
  • pancreatic cancer  
  • toxemia of pregnancy

Additional conditions under which the test may be performed:

What the risks are
 

     
  • excessive bleeding  
  • fainting or feeling light-headed  
  • hematoma (blood accumulating under the skin)  
  • infection (a slight risk any time the skin is broken)  
  • multiple punctures to locate veins

Special considerations
 
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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