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Rheumatoid Factor (RF) - Immunoglobulin G (IgG) Antibodies to IgG

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

This blood test measures antibodies that your immune system produces against a protein found in other antibodies. These antibodies may indicate an autoimmune condition, such as rheumatoid arthritis.

Quick summary

["RF testing helps identify possible autoimmune diseases like rheumatoid arthritis."]

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

Key facts at a glance

LOINC
53924-7
Short code
Rheumatoid fact Titr Snv LA
Synonyms
Rheumatoid fact Titr Snv LA
Category
chemistry
Sample
fluid
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
la
Specimen volume
2-5 mL
Stability
Room temperature: 2h, Refrigerated: 24h
Hemolysis max
300
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test if you have symptoms like joint pain, swelling, or stiffness, especially if they suspect an autoimmune disorder. It can also be used as part of a routine check for certain conditions or during monitoring of existing autoimmune diseases.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The sample is then analyzed in a lab to detect specific antibodies that target other antibodies in your blood.

What to Expect Before the Test

No special preparation is needed. You can eat and drink normally before the test. If you are on blood thinners, inform your healthcare provider beforehand.

What to Expect During the Test

You may feel slight discomfort or a pinch when the needle is inserted, but the procedure usually takes only a few minutes. You might experience some bruising or swelling at the injection site.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Rheumatoid Factor is often positive in people with rheumatoid arthritis but can also be found in other autoimmune diseases, infections, or certain non-autoimmune conditions. While a positive RF test increases the likelihood of rheumatoid arthritis, it is not definitive on its own. Other tests and clinical findings are needed for a diagnosis.

Short name

RF (IgG)

Frequently asked questions

What does a positive RF test mean?
A positive RF test suggests there may be an autoimmune response, but it doesn’t confirm a diagnosis of rheumatoid arthritis alone. It can be part of the evaluation for other conditions, including infections or other autoimmune diseases.
Can RF test results change over time?
Yes, RF levels can fluctuate. They may increase during active disease phases and decrease when symptoms improve. Regular monitoring can help track disease progression or response to treatment.
Does RF test have any false positives?
Yes, RF can be positive in people without rheumatoid arthritis, especially in older adults or those with certain infections or other conditions. False positives can occur, so additional testing and clinical correlation are usually required.
  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