Antinuclear Antibodies (ANA)

An antinuclear antibody (ANA) test measures the amount and pattern of antibodies in your blood that work against your own body (autoimmune).

The body's immune system normally attacks and destroys foreign substances such as bacteria and viruses. However, 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.

An antinuclear antibodies (ANA) test is done to help identify problems with the immune system, such as:

• Rheumatoid arthritis.
• Systemic lupus erythematosus (SLE).
• Polymyositis.
• Scleroderma.
• Sjögren's syndrome.

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?).

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.

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.

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.

An antinuclear antibody (ANA) test measures the amount and pattern of antibodies in your blood that work against your own body (autoimmune).

The results of an ANA test are usually given in titers. A titer is a measure of how much the blood sample can be diluted before the presence of the antibodies can no longer be detected.

For example, a titer of 1 to 40 (1:40) means that antibodies can be detected when 1 part of the blood sample is diluted by up to 40 parts of a salt solution (saline). A larger second number means there are more antibodies in the blood. Therefore, a titer of 1 to 80 indicates more antibodies in the blood than a titer of 1 to 40.

There are different subtypes of ANA which may have a range of normal values.

Normal

Normal values may vary from lab to lab. Results will usually be available in about 1 week.

High values

A high ANA titer may be caused by:

• Autoimmune connective tissue diseases. Examples include:
  • Rheumatoid arthritis. More than one-third of people with rheumatoid arthritis have a high ANA titer.
  • Systemic lupus erythematosus (SLE). Almost all people with SLE have a high ANA titer. However, most people with a high ANA titer do not have SLE.
  • Scleroderma.
  • Sjögren's syndrome.
  • Juvenile rheumatoid arthritis.
  • Polymyositis.
  • Raynaud's syndrome.
• Autoimmune diseases of other organs. Examples include:
  • Addison's disease.
  • Diseases of the blood cells, such as vitamin B12 deficiency, idiopathic thrombocytopenia (ITP), and hemolytic anemia.
  • Liver disease, such as hepatitis.
  • Thyroid disease, such as Hashimoto's thyroiditis.
• Medicines, such as those used to treat high blood pressure, heart disease, and tuberculosis (TB).
• Viral infections.

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 (5% to 40%) may have mildly elevated levels. Older women appear to have higher ANA titers than older men.

• Autoimmune diseases cannot be diagnosed by the results of the ANA test alone. A complete medical history, physical examination, and the results are 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 ANA titer. For instance, some people with a family history of autoimmune disease may have a high ANA titer. The higher the titer, however, the more likely it is that the person has an autoimmune disease.
• ANA levels can increase as a person ages.

Other Works Consulted

• Handbook of Diagnostic Tests (2003). 3rd ed. Philadelphia: Lippincott Williams and Wilkins.

• Pagana KD, Pagana TJ (2006). Mosby’s Manual of Diagnostic and Laboratory Tests, 3rd ed. St. Louis: Mosby.