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Serum/plasma concentration of immunoglobulin G (IgG) subtypes (e.g., IgG1, IgG2, IgG3, IgG4) via immunoassay

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

This test measures specific types of antibodies (IgG subclasses) in your blood, which play a key role in immune defense. It helps identify if certain antibody levels are too high or too low, which can affect immunity or response to infections.

Quick summary

["IgG subclass testing helps diagnose immune system disorders or evaluate immune responses to vaccines or treatments."]

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

Key facts at a glance

LOINC
75750-0
Short code
RF Guided I-disc Bx
Synonyms
RF Guided I-disc Bx
Category
chemistry
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

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like frequent infections, autoimmune conditions, or if you’re receiving treatments that affect antibody production. It can also help assess immune function before or after vaccination.

What to Expect Before the Test

No special preparation is needed for this blood test. You may fast before the draw if instructed, but the test itself doesn’t require fasting. Bring any medications or questions to your appointment.

How the Test Works

A small sample of your blood is taken from a vein, usually in your arm. The blood is then analyzed in a lab to measure the levels of IgG subclasses using an immunoassay method, which detects and quantifies specific antibodies.

What the Results Mean

Results show the concentration of each IgG subclass (IgG1, IgG2, IgG3, IgG4) compared to a reference range. Abnormal levels may indicate immune system issues, such as low immunity, overactive immune responses, or certain diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG subclass levels

Frequently asked questions

What causes IgG subclass levels to be abnormal?
Abnormal IgG subclass levels can result from genetic disorders, chronic illnesses, immune system disorders (like lupus or rheumatoid arthritis), or treatments that suppress or enhance antibody production. Frequent infections or poor immune responses may also be linked to these findings.
How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
Can lifestyle changes affect IgG subclass test results?
While diet and overall health influence immune function, IgG subclass test results are primarily based on blood analysis. However, maintaining a balanced diet, managing stress, and avoiding smoking can support general immune health, which may indirectly affect immune responses.
  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