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Immunoassay for Immunoglobulin G (IgG) Subclass Measurement (Serum/Plasma)

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

This test measures the specific levels of different subclasses of Immunoglobulin G (IgG), a key antibody protein in your immune system. IgG subclasses help fight infections and support immune responses.

Quick summary

["Understanding your IgG subclass levels can help diagnose or monitor immune-related conditions."]

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

Key facts at a glance

LOINC
2458-8
Short code
IgA SerPl-mCnc
Synonyms
IgA SerPl-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms or conditions linked to abnormal IgG subclass levels, such as recurrent infections, autoimmune diseases, or immune deficiencies. It could also be part of a broader evaluation for chronic illnesses or before certain treatments that affect immunity.

What to Expect During the Test

A small blood sample is drawn from a vein in your arm. The sample is then processed and tested for IgG subclass concentrations using an immunoassay method. Results are typically available within a few days.

What the Results Mean

IgG is divided into four subclasses (IgG1, IgG2, IgG3, IgG4). Each subclass plays a distinct role in immunity. Abnormal levels of any subclass may indicate underlying immune system issues, such as deficiencies or overactivity.

Common Conditions Affecting IgG Subclasses

Conditions like common variable immunodeficiency (CVID), HIV/AIDS, or certain autoimmune diseases (e.g., lupus) can alter IgG subclass levels. High or low levels may also be seen in chronic infections or after treatments like chemotherapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG subclass testing is crucial for diagnosing and managing immune-related disorders. For example, low IgG2 levels might suggest trouble fighting certain bacteria, while high IgG3 levels could indicate overactive immune responses or inflammation. Regular monitoring helps tailor treatments to your specific needs.

Short name

IgG Subclass Levels

Frequently asked questions

What does an abnormal IgG subclass result mean?
An abnormal result doesn’t necessarily mean you have a serious condition. It may signal an immune issue that needs further evaluation, such as additional blood tests, immune function assessments, or a referral to an immunologist. Your healthcare provider will discuss the results and next steps with you.
How often should I get this test?
Frequency depends on your medical history and treatment plan. If you have an immune disorder, your provider may recommend periodic testing to monitor changes in IgG subclass levels. If you’re healthy, this test may not be routine unless symptoms arise.
Can lifestyle changes affect IgG subclass levels?
While diet, exercise, and stress management can support overall immune health, IgG subclass levels are primarily influenced by genetic factors, immune system activity, and underlying health conditions. Your provider will guide you on how lifestyle factors may interact with your test 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