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 to 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 blood1| 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 urine1| 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 ratio1| Normal: | 1%–4% or 0.01–0.04 clearance fraction |
|---|
High values
Values may be high because of:
- Inflammation of the pancreas (pancreatitis), a pancreatic cyst, or cancer of the pancreas.
- Inflammation of the
salivary glands, such as
mumps.
- Blockage of or severe damage to
the intestines (bowel obstruction or strangulation).
- A
stomach ulcer that has caused a hole in the stomach
wall.
- Gallstones that are causing
pancreatitis.
- Diabetic ketoacidosis.
- A ruptured
ectopic pregnancy.
- Kidney failure.
- Appendicitis or peritonitis.
- 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.
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.
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 topic
Creatinine.
References
Citations
- 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 |
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| Last Revised | April 8, 2011 |
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