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Immunoglobulin G (IgG) Subclass 1, 2, 3, and 4 Concentration (Serum/Plasma)

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

This test measures the levels of different subclasses of Immunoglobulin G (IgG), a key protein in your immune system. IgG subclasses help protect against infections and play roles in immune responses.

Quick summary

["Understanding your IgG subclass levels can help identify immune system function and potential deficiencies."]

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

Key facts at a glance

LOINC
10492-7
Short code
IgG HC Ag Tiss Ql ImStn
Synonyms
IgG HC Ag Tiss Ql ImStn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immune-stain
CPT
82784
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 Is Done

Doctors may order this test to evaluate immune function, diagnose conditions like hypogammaglobulinemia (low IgG), or monitor treatment for immune-related disorders. It can also help assess immune responses to vaccines or infections.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from a vein in your arm. If you’re on blood thinners, inform your healthcare provider before the test.

What the Results Mean

Results show the concentration of IgG subclasses (IgG1, IgG2, IgG3, IgG4) in your blood. While reference ranges vary by lab, abnormal levels may indicate immune system issues or other health concerns.

Common Conditions Linked to IgG Subclass Results

Low levels of certain IgG subclasses may suggest immune deficiencies, chronic infections, or autoimmune diseases. High levels could be linked to certain inflammatory conditions or overactive immune responses.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG subclasses are vital for immune defense, and their balance is crucial for protecting against infections. Abnormal results often prompt further evaluation, such as additional blood tests or immune function studies.

Short name

IgG Subclass Levels

Frequently asked questions

What causes IgG subclass test results to be abnormal?
Abnormal IgG subclass results can arise from genetic immune deficiencies, chronic illnesses (like lupus or HIV), certain medications, or conditions affecting antibody production. Your doctor will consider your medical history and symptoms to determine the cause.
How long does it take to get IgG subclass test results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Follow-up with your healthcare provider to discuss the findings and next steps.
Can IgG subclass test results change over time?
Yes, IgG subclass levels can fluctuate due to infections, vaccinations, aging, or underlying health conditions. Regular monitoring may be needed if you have a known immune disorder or if treatment is being adjusted.
  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