Amylase - blood

Definition

An amylase test measures the amount of the enzyme amylase in serum (blood). Amylase can also be tested in urine. See amylase - urine.

Why the Test is Performed

This test is primarily performed to diagnose or monitor diseases of the pancreas. It may also detect some digestive tract 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.

How the Test is Performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band or blood pressure cuff is placed around the upper arm. This causes veins below the band to swell 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 band is removed to restore blood flow. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, 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 stop taking 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.

For infants and children:

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• School age test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

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.

Risks

• 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

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.

Normal Results

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
• Gallbladder attack resulting from disease
• Infection of the salivary glands (such as mumps) or an obstruction
• Intestinal obstruction
• Macroamylasemia
• Pancreatic or bile duct obstruction
• Perforated ulcer
• Tubal pregnancy (may be ruptured)
• Viral gastroenteritis

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:

• Chronic pancreatitis
• Diabetic ketoacidosis
• Pancreatic pseudocyst