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Rheumatoid Factor (RF) Autoantibody Test

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

A blood test that detects rheumatoid factor, an antibody sometimes associated with rheumatoid arthritis and other autoimmune conditions.

Quick summary

["A positive rheumatoid factor result may support an autoimmune diagnosis, but it 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
43477-9
Short code
RF Guided BD+PD Endo--1h p con ret IB
Synonyms
RF Guided BD+PD Endo--1h 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?

The rheumatoid factor test looks for RF antibodies in a blood sample. These antibodies are often directed against a part of the body's own immune system.

Why might I need this test?

A clinician may order this test when joint pain, swelling, or stiffness could be related to rheumatoid arthritis or another autoimmune condition. It is often considered along with symptoms, physical findings, and tests for specific antibodies.

How is the test performed?

A blood sample is collected and examined for rheumatoid factor using a laboratory method. The report may provide a qualitative result or a measured concentration, depending on the test used.

How do I prepare for the test?

This test usually requires no special preparation. Follow your clinician's instructions about other medicines, and tell the laboratory if you have received recent antibody treatments such as monoclonal antibody therapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Rheumatoid Factor (RF) Test

Frequently asked questions

What does the rheumatoid factor test measure?
It detects RF autoantibodies in blood. These antibodies can be associated with autoimmune disease but are not specific to rheumatoid arthritis.
Does a positive rheumatoid factor result mean I have rheumatoid arthritis?
No. RF can be positive in other conditions and in some people without an autoimmune disease, so clinical symptoms and additional tests are needed for diagnosis.
Do I need to fast before this test?
Fasting is generally not required unless your clinician or laboratory gives different 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