Antinuclear Antibody Test

What Is an Antinuclear Antibody Test?

An antinuclear antibody test is a blood test that looks for certain kinds of antibodies in your body. It’s also called an ANA or FANA (fluorescent antinuclear antibody) test.

Antibodies are proteins that your immune system makes to fight off bacteria, viruses, and other germs. But sometimes, your immune system can mistake parts of your own body for foreign invaders. It releases special antibodies, called “autoantibodies,” that attack your cells and tissues. Autoantibodies can damage your joints, skin, muscles, and other parts of your body. And they can be a sign of autoimmune diseases, including:

  • Systemic lupus erythematosus, the most common type of lupus
  • Rheumatoid arthritis
  • Scleroderma
  • Sjogren’s syndrome

Sometimes people with cancer or people taking certain medications test positive on an ANA test. Some people with no health conditions test positive on ANA tests.

Why Would I Need This Test?

Your doctor might order an ANA test if you have symptoms of an autoimmune disease, such as:

Preparing for an ANA Test

You usually don't need to prepare for an ANA test. But let your doctor know ahead of time what medicines, vitamins, and supplements you take. They can affect the ANA test results.

Antinuclear Body Test Procedure

A lab tech will take a sample of your blood -- usually from a vein in your arm. They'll tie a band around the upper part of your arm to make your vein fill with blood and swell up. Then they'll clean the area with an antiseptic and insert a needle into your vein. Your blood will collect into a vial or tube.

The blood test should only take a couple of minutes. After your blood is drawn, the needle and band will be removed, and you'll get a piece of gauze and a bandage placed over the area.

The blood sample will go to a lab to be tested. The lab will check to see if there are antinuclear antibodies in your blood.

Antinuclear Body Test Risks

The blood test has very few risks. You might feel a slight sting as your blood is drawn.You may notice a small bruise later.

You may also have a slight chance of:

  • Dizziness or fainting
  • Bleeding
  • Soreness
  • Bruising

Antinuclear Antibody Test Results

Your test is positive if it finds antinuclear antibodies in your blood. A negative result means it found none. A positive test doesn’t mean that you have an autoimmune condition. Between 3% and 15% of people with no conditions have antinuclear antibodies. Some medicines or other diseases also can cause them.

Not everyone who has an autoimmune disease will test positive. That’s why the ANA blood test is just one part of a doctor’s autoimmune disease diagnosis. They’ll also consider your symptoms, do a physical exam, and most likely do other tests.

Conditions that usually cause a positive ANA test include:

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The ANA test result can sometimes also be positive if you have one of these conditions:

About 20% of healthy people will test positive for antinuclear antibodies, even though they don't have an autoimmune disease. You're more likely to have a false positive result if you:

Would I Need Any Other Tests?

The ANA test only shows that you may have an autoimmune disease; it can't detect the exact one.

If your ANA test is positive, your doctor might test you for ANAs that are specific to certain diseases:

  • An anti-centromere test diagnoses scleroderma.
  • An anti-double-stranded DNA (anti-dsDNA) test diagnoses lupus.
  • An anti-histone test diagnoses lupus that was caused by medicine you took.
  • An ENA panel helps your doctor see which autoimmune disease you have.

Make sure you understand the results of your ANA test. Ask what other tests you need for your diagnosis to be confirmed. Also find out how your test results will affect your treatment.

WebMD Medical Reference Reviewed by Neha Pathak, MD on September 21, 2020

Sources

SOURCES:

American Association for Clinical Chemistry: "ANA."

American College of Rheumatology: "Antinuclear Antibodies (ANA)."

Cleveland Clinic: "Antinuclear Antibody Test in Children."

Lupus Research Alliance: "A Positive ANA Test: Should You Worry?"

Mayo Clinic: "ANA test: How you prepare." "Results," "Why It's Done."

National Heart, Lung, and Blood Institute: "What to Expect With Blood Tests."

UpToDate: "Antinuclear antibodies (ANA) (Beyond the Basics)."

MedLine Plus: “ANA (Antinuclear Antibody) Test.”

National Health Service: “Overview: Blood Tests.”

Frontiers in Immunology: “Autoantibodies in Autoimmune Liver Disease—Clinical and Diagnostic Relevance.”

Johns Hopkins Lupus Center: “Lupus Blood Tests.”

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