Normally, only low levels of amylase are found in the blood or urine. But if the pancreas or salivary glands become damaged or blocked, more amylase is usually released into the blood and urine. In the blood, amylase levels rise for only a short time. In the urine, amylase may remain high for several days.
Why It Is Done
A test for amylase is done to:
- Find pancreatitis and other pancreatic diseases.
- See if the treatment for pancreatitis and other pancreatic diseases is working.
- Check swelling and inflammation of the salivary glands.
How To Prepare
To prepare for an amylase test:
- Do not drink alcohol for 24 hours before the test.
- For a blood test for amylase, do not eat or drink anything except water for at least 2 hours before having the test.
- For a 24-hour urine test for amylase, be sure to drink enough fluids during the test to prevent dehydration.
Many medicines may affect the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?) .
How It Is Done
The health professional drawing your blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put the needle in the vein.
- Clean the needle site with alcohol.
- Put the needle in the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Put a gauze pad or cotton ball over the needle site as the needle is removed.
- Put pressure to the site and then put on a bandage.
Amylase can be measured in a 24-hour or 2-hour urine sample.
A 24-hour urine sample is all of the urine you produce over a 24-hour period.
- You start collecting your urine in the morning. When you first get up, empty your bladder but do not save this urine. Write down the time that you urinated to mark the beginning of your 24-hour collection period.
- For the next 24 hours, collect all your urine. Your doctor or lab will usually provide you with a large container that holds about 1 gal (4 L). The container has a small amount of preservative in it. Urinate into a small, clean container and then pour the urine into the large container. Do not touch the inside of the container with your fingers.
- Keep the large container in the refrigerator for the 24 hours.
- Empty your bladder for the final time at or just before the end of the 24-hour period. Add this urine to the large container and record the time.
- Do not get toilet paper, pubic hair, stool (feces), menstrual blood, or other foreign matter in the urine sample.
A 2-hour urine sample is all of the urine you produce over a 2-hour period. Collect it in the same manner as the 24-hour urine sample, during the 2-hour period your health professional recommends.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is no pain while collecting a 2-hour or 24-hour urine sample.
There is very little chance of a problem from having a blood sample taken from a vein.
- You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
- In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
- Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken.
There are no risks associated with collecting a 2-hour or 24-hour urine sample.
An amylase test measures the amount of this enzyme in a sample of blood taken from a vein or in a sample of urine. Many conditions can change amylase levels. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.
Results are normally available within 72 hours. Normal values vary widely from lab to lab.
|2-hour urine sample:||
2–34 U or 16–283 mckat/hour
|24-hour urine sample:||
24–408 U or 400–6,800 mckat/day
Values may be high because of:
- Inflammation of the pancreas (pancreatitis) or cancer of the pancreas.
- Inflammation of the salivary glands, such as mumps.
- Blockage of or severe damage to the intestines (bowel infarction).
- A stomach ulcer that has caused a hole in the stomach wall.
- Gallstones that are causing pancreatitis.
- Cystic fibrosis .
- Pregnancy and diabetic ketoacidosis.
- A ruptured ectopic pregnancy.
- Macroamylasemia, an uncommon and harmless condition in which amylase is bound to a protein in the blood. This condition can cause amylase levels to be either high or low.
Values may be low because of an uncommon and harmless condition called macroamylasemia, severe liver disease, pregnancy, preeclampsia, or advanced cystic fibrosis.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
- Medicines, including narcotics such as codeine and morphine, birth control pills, diuretics, indomethacin (Indocin), and blood-thinning medicines, such as warfarin (Coumadin) and aspirin.
- Hepatitis , cirrhosis, or extensive damage to the pancreas.
- Chronic pancreatitis, which may be present even though amylase levels are low.
- Drinking a large amount of alcohol before the test.
- Saliva, which contains large amounts of amylase. Coughing, sneezing, or even talking over an uncovered urine or blood specimen can contaminate the specimen and artificially increase amylase values.
- Chronic kidney disease , which may cause high levels when the kidneys are no longer able to remove amylase from the blood.
What To Think About
- Pancreatitis usually causes levels of amylase in the urine to remain high for several days longer than blood amylase levels.
- Babies have little or no amylase at birth. By the end of the first year, a baby's amylase level is the same as an adult's level.
- Lipase is an enzyme produced only by the pancreas. A lipase test may be done at the same time as an amylase test when pancreatitis is suspected. For more information, see the medical test Lipase.
- Occasionally, a test that compares urine amylase with creatinine (a renal clearance ratio) may be done to help diagnose pancreatitis. For more information, see the medical test Creatinine.
Other Works Consulted
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2006). Mosby’s Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.
|Author||Bets Davis, MFA|
|Associate Editor||Tracy Landauer|
|Primary Medical Reviewer||Kathleen Romito, MD - Family Medicine|
|Specialist Medical Reviewer||Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology|
|Last Updated||April 29, 2009|
Last Updated: April 29, 2009
Author: Bets Davis, MFA