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Rheumatoid Factor Test

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

A blood test that measures rheumatoid factor antibodies, which can support evaluation for rheumatoid arthritis and related autoimmune conditions.

Quick summary

["An elevated rheumatoid factor result may support an autoimmune diagnosis 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
43476-1
Short code
RF Guided BD+PD Endo--45m p con ret IB
Synonyms
RF Guided BD+PD Endo--45m 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 produced when the immune system targets the body's own joints. This test measures the amount of RF in a blood sample; some laboratories may also report specific RF antibody classes.

Why might I need this test?

RF testing may be ordered for joint pain, swelling, morning stiffness, or suspected rheumatoid arthritis. It may also be used with other laboratory tests when evaluating other autoimmune or inflammatory conditions.

How is the test performed?

A blood sample is analyzed in the laboratory to detect and measure RF antibodies. The laboratory method and reported units can vary, and some tests provide a numerical concentration while others provide a positive or negative result.

How do I prepare for the test?

RF testing usually requires no fasting or special preparation. Follow any instructions provided by your clinician or laboratory, particularly if additional tests are being ordered at the same time.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Rheumatoid factor (RF)

Frequently asked questions

Does a positive RF test mean I have rheumatoid arthritis?
No. A positive result increases suspicion for an autoimmune condition but can occur with several other conditions. Your clinician should interpret it with your symptoms, physical findings, and other tests.
Can I have rheumatoid arthritis with a negative RF result?
Yes. Some people with rheumatoid arthritis do not have detectable RF. Other antibodies and tests, such as anti-CCP testing, may provide additional information.
Do I need to stop taking medicines before this test?
Usually not. Do not stop prescribed medicines unless your clinician specifically instructs you to do so, because symptoms and other test results are needed to interpret the RF result.
  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