Lupus Symptoms and Diagnostic Tests

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Lupus Symptoms and Diagnostic Tests

Question:

I have a rash covering a good portion of my face. My doctor ran blood tests for lupus. The antinuclear antibody test came back positive. Does this mean I have lupus?

Answer:

No, a positive antinuclear antibody test does not mean you have lupus. You cannot diagnose lupus by a single blood test.

The meaning of this test result depends on your symptoms, the findings from your physical examination, and other test results.

Nearly everyone with lupus has a positive test, but many people with a positive test do not have lupus. Test results that are only slightly positive are often meaningless. Also, diseases other than lupus may be lead to a positive antinuclear antibody test. If your doctor suspects lupus, there are more specific antibody tests that can be performed. (These include the anti-Smith and anti-double-stranded-DNA.)

Keep in mind that a rash on the face may be rosacea, seborrhea, or an allergic reaction, to name a few examples. A skin biopsy may be helpful in sorting out whether lupus is causing your rash.

Lupus (systemic lupus erythematosus) is a disease that causes inflammation in multiple parts of the body. The most common problems are rash and arthritis, but other areas can be affected. Symptoms of lupus may vary widely and include:

• Rash that is worsened by sun exposure

• Sores in the mouth

• Joint pain

• Chest pain

• Fatigue

• Seizures or hallucinations

Some forms of lupus are confined to the skin.

Your doctor should perform a thorough examination. If he or she suspects lupus, additional tests can help determine whether lupus may be affecting areas of the body other than your skin. For example, if you have inflammation of the lining of the lung (pleurisy), a chest X-ray may be needed. More routine tests include:

• Blood counts

• Additional antibody tests

• Blood tests assessing kidney function

• Urine tests to detect blood or protein

If your doctor isn't sure of a diagnosis after a full evaluation, it may be a good idea for you to see a rheumatologist. This specialist is an expert at evaluating and treating suspected lupus and at interpreting antinuclear antibody test results.

Robert Shmerling, M.D., is associate physician and clinical chief of rheumatology at Beth Israel Deaconess Medical Center and an associate professor in medicine at Harvard Medical School. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program and has been a practicing rheumatologist for over 25 years.

Last updated:	July 20, 2009