What Is a Positive Rheumatoid Factor?

Written by holly huntington
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The condition of rheumatoid arthritis is sometimes diagnosed when doctors perform a blood test to measure the rheumatoid factor within the body. The presence of this rheumatoid factor (an autoantibody) is a marker that alerts doctors that certain proteins exist in your body that are prone to attacking healthy tissue; however, that does not automatically mean they will. The rheumatoid factor test can give a negative reading (indicating the rheumatoid factor is not present in the blood) or a positive reading (indicating it is present).

Rheumatoid Factor Defined

For an unknown reason, the immune system in the body sometimes produces proteins that attack the body's own healthy tissues. These destructive proteins are called the rheumatoid factor.

Negative vs. Positive Rheumatoid Factors

Generally, the word "positive" has a good connotation and the word "negative" has a bad one. However, in the case of Rheumatoid Factor blood testing, it is just the opposite. If the test comes back as positive, it indicates that the individual does have rheumatoid factor in their blood. Therefore, that can be an indicator of the possible presence of an autoimmune disease such as rheumatoid arthritis or other disease.


A positive rheumatoid factor test does not always mean that the patient has -- or will ever have -- rheumatoid arthritis or any other autoimmune disease. It only means that there is a high probability, since most people who have a positive rheumatoid factor do have some type of autoimmune disease.

Autoimmune Diseases with High Positive Rheumatoid Factor Levels

Rheumatoid factor levels can be raised by more than just rheumatoid arthritis. They can be raised due to cancer, a chronic infection of some kind or cirrhosis. In addition, inflammatory lung diseases or connective tissue diseases can also raise rheumatoid factor levels, as can systemic lupus erythematosus, sjogren's syndrome or scleroderma.


While getting a positive rheumatoid factor result from a blood test can serve as an indicator that something may be wrong with the body's immune system, additional testing is usually performed to confirm which autoimmune disease or condition is actually being experienced, if any at all.

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