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

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

This test measures the presence of antibodies in your blood that target another type of antibody, often linked to rheumatoid arthritis and other autoimmune conditions.

Quick summary

["Rheumatoid factor helps identify possible autoimmune diseases, though it’s not definitive on its own."]

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

Key facts at a glance

LOINC
31046-6
Short code
Rheumatoid fact Fld Ql
Synonyms
Rheumatoid fact Fld Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms of rheumatoid arthritis, such as joint pain, swelling, or stiffness, or if you have other autoimmune conditions. It can also be used to monitor disease activity in people already diagnosed with rheumatoid arthritis or other autoimmune diseases.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Bring any medications you’re currently taking to your appointment.

What Happens During the Test

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis.

What the Results Mean

Rheumatoid factor results are often reported as positive or negative. A positive result suggests the presence of these antibodies, which may indicate an increased risk of autoimmune diseases. However, a positive result alone doesn’t confirm a diagnosis—other tests and clinical findings are needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Rheumatoid Factor (IgG)

Frequently asked questions

What Does a High or Low Result Indicate?
A high rheumatoid factor level is most commonly associated with rheumatoid arthritis, but it can also appear in other autoimmune diseases like lupus or Sjogren’s syndrome. It may also be found in older adults or people with certain infections. A low or negative result means these antibodies are not detected in your blood.
Can Rheumatoid Factor Predict Disease Progression?
While rheumatoid factor can signal an increased risk of autoimmune diseases, it doesn’t always predict how your condition will develop. Other tests, such as imaging studies or additional blood tests, are used alongside rheumatoid factor to assess disease activity and guide treatment.
Does This Test Have False Positives or Negatives?
Yes, rheumatoid factor tests can sometimes produce false positives, especially in older adults or those with certain infections. False negatives are less common but can occur, particularly in early-stage autoimmune diseases. Your doctor will consider the full clinical picture when interpreting results.
  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