RA Factor (Rheumatoid Factor)
Also known as: Rheumatoid factor, RF test, RA factor test, jodon ke dard ka test
Rheumatoid factor (RF or 'RA factor') is an antibody often found in rheumatoid arthritis, an autoimmune disease that causes painful, swollen joints.
Why it's ordered
Joint pain and swelling, especially in the small joints of the hands and feet, with morning stiffness lasting more than 30 minutes.
Preparation
No preparation needed.
Typical adult values
| Negative | below about 14–20 IU/mL (lab-specific) |
|---|
Ranges vary between labs and methods. Always use the range printed on your report.
If it's positive / reactive
A positive RF supports rheumatoid arthritis when the symptoms fit, but it is not a diagnosis by itself. RF can also be positive in healthy older people, hepatitis C, Sjögren's syndrome and some infections. A rheumatologist makes the diagnosis from the joint examination, blood tests and scans.
Good to know
Many people with rheumatoid arthritis have a negative RF, especially early on. The anti-CCP antibody test is more specific for rheumatoid arthritis. Early treatment by a specialist helps prevent joint damage, so persistent swollen joints should not be ignored.
Common questions
Does a positive RA factor mean rheumatoid arthritis?
Not by itself. RF can also be positive in healthy older people, hepatitis C, Sjögren's syndrome and some infections.
Can I have rheumatoid arthritis with a negative RA factor?
Yes. Many people with rheumatoid arthritis have a negative RF, especially early on.
Which test is more specific than RA factor?
The anti-CCP antibody test is more specific for rheumatoid arthritis.
What is a negative RA factor value?
Typically below about 14–20 IU/mL, depending on the lab. Always use the range printed on your report.