
08/05/2024
Rheumatoid Factor (RF) and the RF test:
*What is Rheumatoid Factor (RF)?*
Rheumatoid Factor (RF) is an autoantibody, a type of protein produced by the immune system. In people with rheumatoid arthritis (RA), the immune system mistakenly attacks the lining of the joints, and RF is produced in response to this attack. RF can also be present in other autoimmune disorders, such as Sjogren's syndrome, lupus, and vasculitis.
*What is the RF test?*
The RF test is a blood test used to measure the level of RF in the blood. The test is performed by taking a blood sample from a vein in the arm, and the results are measured in units per milliliter (U/mL).
*What do the results mean?*
- A normal result is typically less than 20 U/mL.
- A result between 20-50 U/mL may indicate a mild increase in RF, which can be seen in people with early RA or other autoimmune disorders.
- A result above 50 U/mL is generally considered positive and may indicate:
- Rheumatoid arthritis (RA)
- Other autoimmune disorders (e.g., Sjogren's syndrome, lupus, vasculitis)
- Inflammatory conditions (e.g., infection, cancer)
*Important notes:*
- A positive RF test does not necessarily mean you have RA or another autoimmune disorder.
- A negative RF test does not rule out RA or other autoimmune disorders.
- The RF test is just one tool used in diagnosis; your healthcare provider will consider other factors, such as symptoms, physical examination, and imaging studies, to make a diagnosis.
I hope this helps! Let me know if you have any further questions.