Antinuclear antibody panel

Definition

The antinuclear antibody panel is a blood test that looks at antinuclear antibodies (ANA).

Antinuclear antibodies are substances produced by the immune system that attack the body's own tissues.

See also: Autoimmune disorder

Alternative Names

ANA; ANA panel

How the test is performed

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

How to prepare for the test

No special preparation is needed. However, certain drugs, including birth control pills, procainamind, and thiazide diurectics, affect the accuracy of this test. Make sure your doctor knows about all the medicines you take.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

Your doctor may order this test if you have signs of an autoimmune disorder, particularly systemic lupus erythematosus. This test may be done if you have unexplained symptoms such as arthritis, rashes, or chest pain.

Normal Values

Usually, there is no detectable ANA in the blood (negative test). Sometimes, however, people who do not have any specific disease may have low levels of ANA for no obvious reason.

ANA is reported as a "titer." Low titers are in the range of 1:40 to 1:60. A positive ANA is much more significant if you also have antibodies against the double-stranded form of DNA.

ANA does not confirm a diagnosis of systemic lupus erythematosis (SLE). However, a lack of ANA makes that diagnosis much less likely.

Although the ANA is most often identified with SLE, a positive ANA can also be a sign of other autoimmune diseases.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

What abnormal results mean

The presence of ANA in the blood may be due to:

• Chronic liver disease
• Collagen vascular disease
• Drug-induced lupus erythematosus
• Myositis (inflammatory muscle disease)
• Rheumatoid arthritis
• Sjogren syndrome
• Systemic lupus erythematosus

Increased ANA levels may sometimes be seen in people with:

• Systemic sclerosis (scleroderma)
• Thyroid disease

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Special considerations

The ANA can be positive in relatives of people with SLE who do not have SLE themselves.

A positive ANA always needs further evaluation, including a careful history, physical exam, and blood tests for other antibodies, especially anti-double-strand DNA antibodies.

If the only finding is a low titer of ANA and everything else is negative, there is only a 5% chance of that patient developing systemic lupus erythematosis at some time later in life.

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