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The Rheumatoid Factor (RF) test is used to help diagnose rheumatoid arthritis (RA) and other autoimmune diseases. RF is an antibody produced by the immune system that can attack healthy tissue. While a positive RF test is often associated with RA, it's not definitive, as some people with RA may have negative results, and some without RA may have positive results. The test is often used in conjunction with other tests, such as anti-CCP antibodies, to improve diagnostic accuracy. RF levels can also be monitored to assess disease activity and treatment effectiveness in patients with confirmed RA.
Acceptable Range: 0 to 14
Ideal for Women: < 14
Ideal for Men: < 14
Ideal for Girls: < 14
Ideal for Boys: < 14
Test Method: blood
What do readings below 0 IU/mL for Rheumatoid Factor - RF mean?
A low or negative RF result (below the range_lower) generally indicates that rheumatoid factor is not present in the blood. This can mean:
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The person likely does not have rheumatoid arthritis or other autoimmune diseases associated with RF.
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If RA is still suspected, further testing may be needed, as some people with RA (seronegative RA) don’t produce RF.
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The test may have been performed too early in the disease process.
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Treatment for RA may be effective in reducing RF levels.
What do readings above 14 IU/mL for Rheumatoid Factor - RF mean?
A high RF result (above the range_upper) indicates the presence of rheumatoid factor in the blood. This can mean:
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The person may have rheumatoid arthritis or another autoimmune disease.
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Higher levels often correlate with more severe disease or a poorer prognosis in RA.
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It’s not definitive for RA, as RF can be elevated in other conditions like Sjögren’s syndrome, lupus, or chronic infections.
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Some healthy individuals, especially older adults, may have elevated RF without any disease.
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Further testing and clinical evaluation are necessary for a definitive diagnosis.