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Rheumatoid Factor (RF) Test

Published: August 9, 2026Updated: August 16, 2026

Rheumatoid factor is an antibody measured in blood that can help evaluate rheumatoid arthritis and certain other immune conditions.

Quick summary

["A positive RF result may support an immune or inflammatory condition but must be interpreted with symptoms and other tests."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
43558-6
Short code
RF Guided DC change--W contr IV
Synonyms
RF Guided DC change--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
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 some people’s immune systems produce. It is usually measured from a blood sample to help evaluate inflammatory joint disease and other immune-related conditions.

Why might I need this test?

Your clinician may order an RF test if you have joint pain, swelling, stiffness, or symptoms suggesting an autoimmune or inflammatory condition. It may also be used alongside other laboratory tests to assess a suspected condition.

How is the test performed?

A blood sample is analyzed in the laboratory for RF. The exact laboratory method and whether the result is reported as positive or negative, a titer, or a concentration can vary.

How do I prepare for the test?

RF testing usually requires no special preparation. Follow your clinician’s instructions and tell the laboratory if you have recently received biologic medicines or immune treatments, because these can affect antibody measurements.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A positive RF result may occur with rheumatoid arthritis, other autoimmune diseases, some chronic infections, and in some healthy older adults. A negative result does not completely rule out rheumatoid arthritis or another inflammatory condition, so results should be interpreted with symptoms, examination findings, and other tests.

Short name

Rheumatoid Factor

Frequently asked questions

Does a positive rheumatoid factor result mean I have rheumatoid arthritis?
No. RF can be positive in several conditions and in some healthy people. Your clinician will interpret it together with your symptoms and other test results.
Can I have rheumatoid arthritis with a negative RF result?
Yes. Some people with rheumatoid arthritis have little or no RF, so a negative result does not exclude the condition.
Are other antibody tests needed?
Often. Tests such as anti-CCP antibodies, ANA, and other laboratory studies may help clarify the diagnosis when RF results need additional context.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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