Test Overview
An antinuclear
antibody (ANA) test measures the amount and pattern of
antibodies in your blood that work against your own
body (autoimmune reaction).
The body's
immune system normally attacks and destroys foreign
substances such as bacteria and viruses. But in disorders known as
autoimmune diseases, the immune system attacks and
destroys the body's normal tissues. When a person has an autoimmune disease,
the immune system produces antibodies that attach to the
body's own cells as though they were foreign substances, often causing them to
be damaged or destroyed.
Rheumatoid arthritis and
systemic lupus erythematosus are examples of
autoimmune diseases.
An ANA test is used along with your symptoms,
physical examination, and other tests to find an autoimmune disease.
Why It Is Done
An antinuclear antibodies (ANA) test is
done to help identify problems with the immune system, such as:
How To Prepare
You do not need to do anything before
you have this test.
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 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 a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into 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.
- Apply a gauze pad or cotton ball over the needle site as
the needle is removed.
- Apply pressure to the site and then a
bandage.
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.
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.
Results
An antinuclear antibody (ANA) test
measures the amount and pattern of
antibodies in your blood that work against your own
body (autoimmune reaction). If there are more antibodies in the blood than normal, the
test is positive. When the test is positive, most labs do other tests right
away to look for the cause. These tests can find out which antibodies are in
the blood in higher amounts than normal.
Positive test
A positive ANA test may be caused
by:
- Autoimmune connective tissue diseases.
Examples include:
- Autoimmune diseases of other organs. Examples
include:
- Medicines, such as those used to treat high
blood pressure, heart disease, and tuberculosis (TB).
- Viral
infections.
What Affects the Test
Reasons you may not be able to
have the test or why the results may not be helpful include:
- Taking medicine. Many medicines can change the
results of this test. Be sure to tell your doctor about all the nonprescription
and prescription medicines you take.
- Aging. Some older adults may have mildly elevated levels. These people do not have lupus.
- A
virus. Viral illness can cause an ANA to be positive,
and later turn back to normal.
What To Think About
- Autoimmune diseases cannot be diagnosed by the
results of the ANA test alone. A complete medical history, physical
examination, and the results of other tests are used with the ANA test to help
identify autoimmune diseases, such as systemic lupus erythematosus (SLE) or
rheumatoid arthritis.
- Some healthy people can have an increased
amount of ANA in their blood. For instance, this can happen in some people with
a family history of
autoimmune disease. The higher the ANA level is,
however, the more likely it is that the person has an autoimmune
disease.
- ANA levels can increase as a person ages.
References
Other Works Consulted
- 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 |
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| Primary Medical Reviewer | Kathleen Romito, MD - Family Medicine |
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| Specialist Medical Reviewer | E. Gregory Thompson, MD - Internal Medicine |
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| Last Revised | June 11, 2010 |
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