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Understanding the Blood Test Numbers for Rheumatoid Arthritis

Unlike other forms of arthritis, there is a specific blood test available to check for rheumatoid arthritis. This test, combined with arthritic pain on both sides of the body, indicates whether a person is suffering from rheumatoid arthritis.

  1. Identification

    • The blood test used to diagnose rheumatoid arthritis detects rheumatoid factor (RF) antibodies, which tend to be high in people with rheumatoid arthritis, according to Medline Plus.

    Normal Range

    • People with a normal level of RF antibodies have a result of either less than 40-60 u/mL or less than 1:80 (1 to 80) titer (a titer is the concentration of the antibody in your blood).

    Abnormal Range

    • People with greater than 60 u/ml or 1:80 titer on the RF antibody test may have rheumatoid arthritis. However, Medline Plus notes that normal and abnormal values vary based on the laboratory. Consult your doctor to help understand your results.

    Considerations

    • It is possible to have a high RF antibody level without having rheumatoid arthritis; it is similarly possible in some cases for people with rheumatoid arthritis to not have elevated RF antibodies.

    Potential

    • Another antibody blood test, the anti-citrullinated peptide antibody test is beginning to be used as a potentially more accurate way of diagnosing rheumatoid arthritis, since 96 percent of people with rheumatoid arthritis have this antibody, according to Merck Manuals.

    Types

    • Other blood tests are sometimes used to check for or monitor rheumatoid arthritis, but they are not specific to the condition; these tests include erythrocyte sedimentation rate test, C-reactive protein and anemia tests.

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