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Rheumatoid Factor (RF) Test

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

This test detects or measures rheumatoid factor, an antibody that may be elevated in autoimmune conditions such as rheumatoid arthritis.

Quick summary

["A positive rheumatoid factor can support an autoimmune diagnosis, but it must be interpreted with symptoms and other test results."]

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

Key facts at a glance

LOINC
94094-0
Short code
RFA Vs Ltd W contr via exist cath
Synonyms
RFA Vs Ltd W contr via exist cath
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?

Rheumatoid factor (RF) is an antibody that can be detected or measured in a blood sample. It may be present in people with rheumatoid arthritis and other autoimmune conditions.

Why might I need this test?

Your clinician may order this test to help evaluate persistent joint pain, swelling, or stiffness, especially when rheumatoid arthritis is suspected. It may also be used alongside other laboratory and clinical findings.

How is the test performed?

A laboratory test is performed on a patient sample. The order appears to include collection through an existing catheter, so follow your care team's instructions about the required specimen and collection method.

How do I prepare for the test?

RF testing usually does not require fasting, but follow any specific instructions provided with the order. Tell the care team if you have symptoms of infection around an existing catheter.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Rheumatoid Factor

Frequently asked questions

Does a positive rheumatoid factor mean I have rheumatoid arthritis?
No. RF is not specific to rheumatoid arthritis and may be present in other conditions or in healthy older adults. Your clinician will interpret it in your overall clinical context.
Can I have rheumatoid arthritis with a negative RF result?
Yes. Some people with rheumatoid arthritis have little or no detectable RF, so other findings and tests are important.
Is fasting required for this test?
Fasting is generally not required for RF testing, although the collection method or other tests ordered at the same time may have specific preparation instructions.
  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