How is it used?
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When is it ordered?
The test for RF may be ordered when a patient has signs of
RA. Symptoms may include pain, warmth, swelling, and morning stiffness in the joints, nodules under the skin, and, if the disease has progressed, evidence on X-rays of swollen joint capsules and loss of
cartilage and bone. An RF test may be repeated when the first test is negative and symptoms persist. The RF test also may be ordered when a patient has symptoms suggesting
Sjögren’s syndrome. Symptoms may include an extremely dry mouth and eyes, dry skin, and joint and muscle pain. Symptoms may also be mixed as patients may have more than one
autoimmune disorder. Patients with RA and/or Sjogren’s syndrome may also have other connective tissue disorders such as Raynaud’s syndrome, scleroderma, autoimmune thyroid disorders, and
systemic lupus erythematosis.
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What does the test result mean?
In patients with symptoms and clinical signs of
rheumatoid arthritis, the presence of significant concentrations of RF indicates that it is likely that they have RA. In patients with the symptoms of
Sjögren’s syndrome, significant concentrations of RF indicate that it is likely that they have Sjögren’s.
A negative RF test does not rule out RA or Sjögren’s syndrome. About 20% of patients with RA and many patients with Sjögren’s syndrome will be persistently negative for RF and/or may have very low levels of RF.
Positive RF test results may also be seen in healthy patients and in patients with conditions such as: ; systemic lupus erythematosus (lupus); tuberculosis; syphilis; sarcoidosis; cancer; viral infection; or disease of the liver, lung, or kidney. The RF test is not used to diagnose or monitor these conditions.
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Is there anything else I should know?
The RF test is not diagnostic or specific. It must be interpreted in conjunction with the patient’s symptoms and history to make a diagnosis of RA, Sjögren’s syndrome, or another condition. The frequency of
false positive RF results increases with age.
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