What is an ANA (antinuclear antibody) test?

An ANA test is a blood test that looks for antinuclear antibodies in your blood. Antibodies are proteins that your immune system makes to fight foreign substances, like viruses and bacteria. But an antinuclear antibody attacks your healthy cells instead. It's called "antinuclear" because it targets the nucleus of the cells, which is in charge of sending signals that are needed for important cell functions.

It's normal to have a few antinuclear antibodies in your blood. But a large number may be a sign of an autoimmune disorder. If you have an autoimmune disorder, your immune system attacks the healthy cells of your organs and tissues by mistake. These disorders can cause serious health problems.

Other names: antinuclear antibody panel, fluorescent antinuclear antibody, FANA, ANA, ANA reflexive panel

What is it used for?

An ANA test is used to help diagnose autoimmune disorders, such as:

• Systemic lupus erythematosus (SLE), the most common type of lupus. Lupus is a chronic (long-lasting) disease that affects many parts of the body, including the joints, skin, heart, lungs, blood vessels, kidneys, and brain.
• Rheumatoid arthritis, a condition that mostly affects joints, causing pain and swelling often in the wrists, hands, and feet.
• Scleroderma, a rare disease that may affect the skin, blood vessels, and organs.
• Sjögren's syndrome, a rare disease that affects the glands that make tears and saliva (spit) and other parts of the body.
• Addison Disease, which affects your adrenal glands (glands on top of the kidneys), causing fatigue and weakness.
• Autoimmune hepatitis, which causes swelling in your liver.
• Thyroid diseases, which can cause your thyroid to make too much or too little thyroid hormones.

Why do I need an ANA test?

Your health care provider may order an ANA test if you have symptoms of an autoimmune disorder. The symptoms depend on what part of your body is affected. They may include:

• Fever
• Rash, blisters, or skin color changes
• Fatigue
• Joint pain, stiffness, and swelling
• Muscle pain
• Swollen glands
• Abdominal (belly) pain

What happens during an ANA test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

Some medicines may affect the results of your ANA test. You may need to stop taking certain medicines before this test, so tell your provider about everything you take. But don't stop taking any medicines unless your provider tells you to.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

Results from an ANA test alone cannot diagnose a specific disease. Your provider will use your ANA test results along with other blood and imaging tests and information about your health to make a diagnosis.

A negative result on an ANA test means that antinuclear antibodies were not found in your blood, and you're less likely to have an autoimmune disorder. But a negative ANA test doesn't completely rule out the possibility that you could have an autoimmune disorder.

A positive result on an ANA test means that antinuclear antibodies were found in your blood. A positive result may be a sign of:

• Systemic lupus erythematosus (SLE)
• A different type of autoimmune disease
• A viral infection (antinuclear antibodies from a virus are usually only in your blood for a short time)
• Another health condition that can cause antinuclear antibodies, such as cancer

If your ANA test results are positive, your provider will likely order more tests to make a diagnosis.

Having antinuclear antibodies in your blood doesn't always mean you have a disease. Some healthy people have antinuclear antibodies in their blood, and levels tend to increase with age. Many healthy adults may have a positive ANA test result, especially women over the age of 65. Also, certain medicines can cause antinuclear antibodies.

If you have questions about your results, talk with your provider.

Learn more about laboratory tests, reference ranges, and understanding results.