ANA test
文章来源: 回家路 于 2015-02-05 09:57:06

An ANA test detects antinuclear antibodies (ANA) in your blood. Your immune system normally makes antibodies to help you fight infection. In contrast, antinuclear antibodies often attack your body's own tissues — specifically targeting each cell's nucleus.

In most cases, a positive ANA test indicates that your immune system has launched a misdirected attack on your own tissue — in other words, an autoimmune reaction. But some people have positive ANA tests even when they're healthy.

Your doctor may order an ANA test if he or she suspects you have an autoimmune disease such as lupus, rheumatoid arthritis or scleroderma.

http://www.mayoclinic.org/
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What does a positive ANA reading mean?

A negative ANA reading means no autoantibodies are present in the body. However, a positive ANA reading alone does not indicate an autoimmune disease. Why?

  • The prevalence of ANAs in healthy individuals is about 3-15%. The production of these autoantibodies is strongly age-dependent, and increases to 10-37% in healthy persons over the age of 65. Even healthy people with viral infections can have a positive ANA, albeit for a short time.
  • Some medications can cause a positive ANA. It is important to talk with your doctor all the drugs you are taking—prescription, over-the-counter and street.
  • Other conditions, such as cancer, can cause a positive ANA.

The positive ANA reading simply tells your doctor to keep looking. In fact, you may have a “false positive” ANA, which means that the evidence is not there to make a diagnosis of lupus or any other autoimmune disease. To make a definite diagnosis, your doctor will need more blood tests along with history of your symptoms and a physical examination.

How should I handle a positive ANA reading?

Please note a positive ANA does not require immediate treatment. Remember, lab levels vary, some autoantibodies are normal and this may be a false positive result. Your doctor will determine what happens next based on additional exploration. By working with your doctor and asking questions you will get the best care for your particular situation.

Keep in mind, even if your ANA reading does lead to an autoimmune diagnosis, there are treatments for autoimmune diseases.

Points to remember

  • Some medications cause a positive ANA. Tell your doctor all prescription, over-the-counter and street drugs you take.
  • ANA testing can produce a “false positive.” This typically signals the presence of antinuclear antibodies in a healthy individual.
  • Talk to your doctor about a positive ANA and best next steps.

The rheumatologist's role in ANA

Your rheumatologist will interpret your ANA in the context of other laboratory studies and your clinical history, including family history. Remember a single positive ANA does not imply autoimmune disease.

http://www.rheumatology.org/practice/clinical/patients/diseases_and_conditions/ana.asp