Inflammation
Rheumatoid Factor
LOINC 11572-5 · IU/mL
What it is
Rheumatoid factor (RF) is an antibody that can be present in rheumatoid arthritis and some other autoimmune conditions.
Why it matters
It helps evaluate joint symptoms and supports the diagnosis of rheumatoid arthritis, though it is not specific on its own.
What high values can mean
A higher value can support a diagnosis of rheumatoid arthritis or other autoimmune conditions, but can also occur in healthy people.
What low values can mean
A lower or negative value makes RF-positive conditions less likely, though it does not rule them out.
How to improve it
RF reflects an autoimmune process, not lifestyle; care focuses on managing any underlying condition.
Food & lifestyle
No diet changes RF; an overall healthy, anti-inflammatory lifestyle supports joint health generally.
Preparing for the test
A blood test; fasting is not required — follow your lab's instructions.
When to talk to a doctor
Discuss a positive RF with a doctor, especially with joint pain, stiffness or swelling.
Related markers
Sources
- MedlinePlus (NIH)
- Testing.com (AACC)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
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