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

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.

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.

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.

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.

Usually, there is no detectable ANA in the blood (negative test). Sometimes, however, people without any specific disease may have low levels of ANA for no apparent reason.

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

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

Increased ANA levels may sometime be seen in people with:

• Systemic sclerosis (scleroderma)
• Thyroid disease

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

Other risks:

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

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