Rheumatoid Factor (RF), Agglutination — Venous Blood
A venous blood test that detects RF antibodies, which may help evaluate rheumatoid arthritis and related autoimmune conditions.
["A positive RF result can support a diagnosis of rheumatoid arthritis, but it must be interpreted with symptoms and other test findings."]
Key facts at a glance
- LOINC
- 26295-6
- Short code
- RFA Guided Vein-Bl CVC repos--W contr IV
- Synonyms
- RFA Guided Vein-Bl CVC repos--W contr IV
- 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-angio
- 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?
This blood test measures rheumatoid factor, an antibody that can bind to other antibodies. It is commonly performed using an agglutination-based laboratory method.
Why might I need this test?
The test may be ordered for people with joint pain, swelling, stiffness, or other symptoms suggesting rheumatoid arthritis or another autoimmune condition. It is usually interpreted together with the medical examination and other laboratory tests.
How is the test performed?
A venous blood sample is collected and analyzed in the laboratory for RF antibodies. If the specimen was obtained through a central venous catheter, the collection source may be noted on the order and report.
How do I prepare for the test?
Fasting is generally not required for this test. Follow the instructions provided by your clinician, and tell the healthcare professional if you are taking medicines that may affect autoimmune laboratory results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A positive RF result may occur in rheumatoid arthritis, but it can also be found in other autoimmune diseases, some chronic infections, and in some healthy people. A negative result does not completely rule out rheumatoid arthritis, particularly early in the disease. The result should therefore be interpreted by a clinician using symptoms, examination findings, and other tests.
Short name
Rheumatoid factor (RF)
Frequently asked questions
Does a positive rheumatoid factor result mean I have rheumatoid arthritis?
Can I have rheumatoid arthritis if this test is negative?
Do I need to fast before this blood 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