Rheumatoid Factor (RF) Test
A blood test that detects rheumatoid factor antibodies, which are often evaluated when inflammatory joint symptoms suggest rheumatoid arthritis.
["An elevated rheumatoid factor can support an inflammatory arthritis evaluation, but it does not diagnose rheumatoid arthritis by itself."]
Key facts at a glance
- LOINC
- 43473-8
- Short code
- RF Guided BD+PD Endo--2h p con ret IB
- Synonyms
- RF Guided BD+PD Endo--2h p con ret IB
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- rf
- CPT
- 86430
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
Rheumatoid factor (RF) is an antibody that can be detected in blood. The supplied code contains unclear qualifiers, so the exact specimen and laboratory method cannot be confirmed from the code alone.
Why might I need this test?
This test may be ordered for joint pain, swelling, stiffness, or tenderness, especially when rheumatoid arthritis is suspected. It may also be used alongside other tests, such as anti-CCP antibodies, to help assess the likelihood of rheumatoid arthritis.
How is the test performed?
A blood sample is collected and analyzed in the laboratory to detect and measure RF antibodies. Depending on the laboratory, the result may be reported as a concentration, titer, or positive or negative result.
How do I prepare for the test?
Fasting is usually not required. Tell your clinician about any autoimmune disease, recent infection, or medicines that may affect the interpretation, and follow the preparation instructions provided by the laboratory.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated RF result may occur with rheumatoid arthritis, but it can also be associated with other autoimmune conditions, chronic infections, liver disease, and increasing age. A negative RF result does not exclude rheumatoid arthritis, particularly early in the disease. Results should be interpreted with symptoms, physical findings, and other laboratory tests.
Short name
Rheumatoid factor (RF)
Frequently asked questions
What does the rheumatoid factor test measure?
Does a positive rheumatoid factor mean I have rheumatoid arthritis?
Do I need to fast before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy