Positive rheumatoid factor blood test: What does it mean?

What conditions — other than rheumatoid arthritis — can cause a positive rheumatoid factor test?

- Joyce / Arizona

Mayo Clinic hematologist Ruben Mesa, M.D., and colleagues answer select questions from readers.

Answer

Rheumatoid factors (RFs) are antibodies that attach to other antibodies and may trigger inflammation in the body. A positive rheumatoid factor test means that rheumatoid factor has been detected in your blood. This test is used mainly to diagnose rheumatoid arthritis (RA) — about 80 percent of people with RA test positive for rheumatoid factor. But other conditions also can cause a positive rheumatoid factor test, including:

Sjogren's syndrome
Chronic mononucleosis
Chronic hepatitis
Lupus
Tuberculosis
Sarcoidosis
Dermatomyositis
Scleroderma
Bacterial endocarditis
Primary biliary cirrhosis
Leukemia

In addition, rheumatoid factor can also be detected in healthy people. It's important to discuss with your doctor the significance of a positive rheumatoid factor test in your specific situation.