I was told that my lab results showed rheumatoid arthritis (RA) in my blood. Does this mean I have RA?

· Rheumatoid factor (RF), an antibody (protein) detected in the blood, is extremely useful in diagnosing rheumatoid arthritis (RA), because about 80% of RA patients have RF in their blood (seropositive RA).

· However, RF can also be present due to other inflammatory diseases. Even some healthy patients have persistent positive RF, without presence of other inflammatory arthritis or other disease.

· Yes, possibly, due to the fact that 20% of RA patients lack RF in their blood (seronegative RA). Generally speaking, the prognosis of seronegative RA is better than seropositive RA because the higher the RF concentration, the more severe the rheumatoid arthritis.

I have a positive ANA. Even though I have no other symptoms, do I have Lupus?

· Over 95% of patients with lupus have a positive ANA, which can, however, also be present with other diseases such as RA, Sjogren’s syndrome, Polymyositis, Scleroderma, hepatitis or interstitial pulmonary disease. Moreover, 20% of healthy women, especially the older we are, have a positive ANA without evidence of Lupus or other inflammatory disease (false positive).

· Therefore, a diagnosis of Lupus cannot be solely based on a positive ANA, but must include a detailed medical history, physical examination and further testing such as anti-ds DNA, anti-ENA and anti-cardiolipin Ab.

· In fact, because lupus is relatively rare, it is far more likely that a positive ANA will be a “false” positive rather than a “true” positive.

Why did my doctor order an anti-DS DNA, anti-ENA and anti-cardiolipin Ab after finding out I had a positive ANA?

· Because patients who have lupus or other connective tissue diseases possess several different antibodies, these tests offer more information for a final diagnosis. For example, if you have positive ANA with positive anti-ds DNA or with positive anti-cardiolipin Ab, the chance of lupus would be higher.

By Dr. Yong H. Tsai
Published in The Daytona Beach News-Journal
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