Antinuclear antibody panel

Definition

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

ANA are antibodies produced by the immune system that bind to the body's own tissues. The antinuclear antibody test looks for antibodies that bind to a part of the cell called the nucleus. The screening test determines whether such antibodies are present. The test also measures the level, called the titer, and the pattern, which can be helpful. If the test is positive, a panel of tests may be done to identify specific antigen targets. This is the ANA antibody panel.

Alternative Names

ANA; ANA panel; ANA reflexive panel; SLE - ANA; Systemic lupus erythematosus - ANA

How the Test is Performed

Blood is drawn from a vein. Most often, a vein on the inside of the elbow or the back of the hand is used. 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 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.

Depending on the laboratory, the test may be processed in different ways. One method requires a technician to examine a blood sample under a microscope using ultraviolet light. The other uses an automated instrument to record the results.

How to Prepare for the Test

No special preparation is needed. However, certain drugs, including birth control pills, procainamide, and thiazide diuretics, affect the accuracy of this test. Make sure your provider 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. Others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed

You may need 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 Results

Some normal people have a low level of ANA. Thus, the presence of a low level of ANA is not always abnormal.

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

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

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

Normal value ranges may vary slightly among different laboratories. Talk to your provider 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.

Further tests can be run on blood with a positive ANA test to get more information.

What Abnormal Results Mean

To make the diagnosis of SLE, certain clinical features as well as ANA must be present. In addition, certain specific ANA antibodies help to confirm the diagnosis.

The presence of ANA in the blood may be due to many other disorders besides SLE. These include:

AUTOIMMUNE DISEASES

• Mixed connective tissue disease
• Drug-induced lupus erythematosus
• Myositis (inflammatory muscle disease)
• Rheumatoid arthritis
• Sjögren syndrome
• Systemic sclerosis (scleroderma)
• Thyroid disease
• Autoimmune hepatitis
• Lymphomas

INFECTIONS

• EB virus
• Hepatitis C
• HIV
• Parvovirus

Risks

Veins and arteries vary in size from one person 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 lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Considerations

Your provider will use the results of the ANA panel to help make a diagnosis. Almost all people with active SLE have a positive ANA. However, a positive ANA by itself is not enough to make a diagnosis of SLE or any other autoimmune disease. The ANA tests must be used along with your medical history, physical exam and other laboratory tests.

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

There is a very low chance of developing SLE at some time later in life if the only finding is a low titer of ANA.

References

Alberto von Mühlen C, Fritzler MJ, Chan EKL. Clinical and laboratory evaluation of systemic rheumatic diseases. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 52.

American College of Rheumatology website. Antinuclear antibodies (ANA). www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Antinuclear-Antibodies-ANA. Updated March 2017. Accessed April 04, 2019.

Reeves WH, Zhuang H, Han S. Autoantibodies in systemic lupus erythematosus. In: Hochberg MC, Gravallese EM, Silman AJ, Smolen JS, Weinblatt ME, Weisman MH, eds. Rheumatology. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 139.