The rheumatoid factor test aids in diagnosing rheumatoid arthritis, also known as RA, says WebMD. The rheumatoid factor is an antibody present in the blood in a majority of people diagnosed with RA.
During the rheumatoid factor test, a sample of the patient's blood is analyzed in a lab where the sample may also be tested for anemia, antinuclear antibodies, inflammation markers and the anti-CCP antibody, notes WebMD. Additional tests that may be completed for a more accurate diagnosis include an ultrasound, MRI and X-rays.
In addition to RA, a rheumatoid factor test can also reveal the presence of other autoimmune disorders, such as Sjogren's syndrome and lupus, says WebMD. Infections such as hepatitis, tuberculosis, syphilis and mononucleosis can also be revealed by the presence of rheumatoid factor. There is also a possibility that the test can reveal cancer.
Physicians may use the test to add to the findings of a standard physical examination and a patient's symptom history, notes WebMD. A rheumatoid factor test may also aid in determining the aggressiveness of the disease.
While a person does not have to undergo special preparation before the test, some may be nervous about having blood drawn. An individual should speak with his doctor about his concerns and inform the doctor if he ever feels nauseated or faint during the test.
The normal levels for a RF blood test is lower than 40 to 60 units per milliliter, reports the National Institutes of Health's MedlinePlus. RF levels that are higher than this range can be indicative of rheumatoid arthritis or Sjogren's syndrome. To aid in a diagnosis of rheumatoid arthritis, doctors can order another blood test called anti-CCP antibody test. Although the RF test is useful in the diagnosis of rheumatoid arthritis or Sjogren's syndrome, it should not be used as a diagnostic test for other conditions, including hepatitis, leukemia, AIDS and mononucleosis.