Antinuclear Antibodies (ANA)

ANA (Antinuclear Antibodies) Test

Results

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 titres. A titre 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 titre 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 titre of 1 to 80 indicates more antibodies in the blood than a titre 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.

Antinuclear antibodies

Normal titre	1:40 or less

High values

A high ANA titre 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 titre.
  • Systemic lupus erythematosus (SLE). Almost all people with SLE have a high ANA titre. However, most people with a high ANA titre do not have SLE.
  • Scleroderma.
  • Sjögren's syndrome.
  • Juvenile idiopathic 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.

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Author:	Douglas Dana Sydney Youngerman-Cole, RN, BSN, RNC	Last Updated: August 31, 2006
Medical Review:	Kathleen Romito, MD - Family Medicine Tom Bailey, MD - Family Medicine Stanford M. Shoor, MD - Rheumatology
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