Rheumatoid factor (RF)

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Results are usually reported in one of two ways:

• Less than 40-60 u/mL
• Less than 1:80 (1 to 80) titer

A low number (normal result) usually means you do not have rheumatoid arthritis or Sjogren syndrome. However, some people who do have these conditions still have a "normal" or low rheumatoid factor (RF).

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

High levels of rheumatoid factor, especially in people who have symptoms, can help diagnose rheumatoid arthritis or Sjogren syndrome. The higher the level reported, the more likely one of these conditions is present.

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People with these autoimmune diseases may also have higher levels of rheumatoid factor:

• Scleroderma
• Systemic lupus erythematosus
• Adult Still's disease
• Dermatomyositis
• Juvenile rheumatoid arthritis
• Sarcoidosis

Many other medical problems and infections may cause higher-than-normal levels of RF. However, RF is not used to diagnose these problems:

• AIDS, hepatitis, influenza, infectious mononucleosis, and other viral infections
• Endocarditis, tuberculosis, and other bacterial infections
• Parasite infections
• Leukemia, multiple myeloma, and other cancers
• Chronic lung disease
• Chronic liver diseases
• Nephrotic syndrome

Sometimes, people who are healthy and have no other medical problem will have a higher-than-normal RF level.

Review Date: 05/31/2009
Reviewed By: Mark James Borigini, MD, Rheumatologist in the Washington, DC Metro area. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).