Amylase - blood

Answer 1

Definition

Amylase is an enzyme that helps digest carbohydrates. It is produced mainly in the pancreas and the glands that make saliva. When the pancreas is diseased or inflamed, amylase releases into the blood.

A test can be done to measure the level of this enzyme in your blood.

Amylase may also be measured with a urine test. See amylase - urine.

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

No special preparation is needed. However, you should avoid alcohol before the test. The health care provider may advise you to stop taking drugs that may affect the test. NEVER stop taking any medications without first talking to your doctor.

Drugs that can increase amylase measurements include:

• Asparaginase
• Aspirin
• Birth Control pills
• Cholinergic medications
• Corticosteroids
• Indomethacin
• Loop and thiazide diuretics
• Methyldopa
• Opiates (codeine, morphine)
• Pentazocine

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 most often used to diagnose or monitor diseases of the pancreas. It may also detect some digestive tract problems.

Additional conditions under which the test may be performed:

• Chronic pancreatitis
• Diabetic ketoacidosis
• Pancreatic pseudocyst

Normal Values

The normal range is 23 to 85 units per liter (U/L). Some laboratories give a range of 40 to 140 U/L.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

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

What the risks are

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

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.

References

Owyang C. Pancreatitis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 147.

Answer 2

Definition

Amylase is an enzyme that helps digest carbohydrates. It is produced in the pancreas and the glands that make saliva. When the pancreas is diseased or inflamed, amylase releases into the blood.

A test can be done to measure the level of this enzyme in your blood.

Amylase may also be measured with a urine test. See amylase - urine.

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture.

How to prepare for the test

No special preparation is needed. However, you should avoid alcohol before the test. The health care provider may ask you to stop taking drugs that may affect the test. NEVER stop taking any medications without first talking to your doctor.

Drugs that can increase amylase measurements include:

• Asparaginase
• Aspirin
• Birth control pills
• Cholinergic medications
• Ethacrynic acid
• Methyldopa
• Opiates (codeine, meperidine, morphine)
• Thiazide diuretics

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 most often used to diagnose or monitor acute pancreatitis. It may also detect some digestive tract problems.

The test may also be done for the following conditions:

• Chronic pancreatitis
• Pancreatic pseudocyst

Normal Values

The normal range is 23 to 85 units per liter (U/L). Some laboratories give a range of 40 to 140 U/L.

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

Increased blood amylase levels may occur due to:

• Acute pancreatitis
• Cancer of the pancreas, ovaries, or lungs
• Cholecystitis
• Gallbladder attack caused by disease
• Gastroenteritis (severe)
• Infection of the salivary glands (such as mumps) or a blockage
• Intestinal blockage
• Macroamylasemia
• Pancreatic or bile duct blockage
• Perforated ulcer
• Tubal pregnancy(may have burst open)

Decreased amylase levels may occur due to:

• Cancer of the pancreas
• Damage to the pancreas
• Kidney disease
• Toxemia of pregnancy

What the risks are

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.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

References

Owyang C. Pancreatitis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 147.

Tenner S, Steinberg WM. Acute pancreatitis. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 58.

Reviewed By

Review Date: 02/04/2011

David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and George F Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.