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Amylase

Test Overview

An amylase test measures the amount of this enzyme in a sample of blood taken from a vein or in a sample of urine.

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

Blood test

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 on the site and then put on a bandage.

Urine test

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

Blood test

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.

Urine test

There is no pain while collecting a 2-hour or 24-hour urine sample.

Risks

Blood test

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.

Urine test

There are no risks associated with collecting a 2-hour or 24-hour urine sample.

Results

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.

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Normal

Amylase in blood 1
Adults age 60 and younger:

25–125 units per liter (U/L) or 0.4–2.1 microkats/liter (mckat/L)

Adults older than age 60:

24–151 U/L or 0.4–2.5 mckat/L

Amylase in urine 1
2-hour urine sample:

2–34 U or 16–283 nanokats/hour

24-hour urine sample:

24–408 U or 400–6,800 nanokats/day

Amylase/creatinine clearance ratio 1
Normal:

1%–4% or 0.01–0.04 clearance fraction

High values

Values may be high because of:

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 opiates such as codeine and morphine, birth control pills, diuretics, indomethacin, and blood-thinning medicines, such as warfarin and aspirin.
  • 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.
  • Being pregnant.
  • Having an endoscopic retrograde cholangiopancreatogram (ERCP) test before the amylase test.

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. To learn more, see the topic Lipase.
  • Occasionally, a test that compares urine amylase with creatinine (a renal clearance ratio) may be done to help diagnose pancreatitis. To learn more, see the topic Creatinine.

References

Citations

  1. Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

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 (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology
Last Revised March 8, 2013

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