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

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

This test measures different types of Immunoglobulin G (IgG), a key protein in your immune system, to help identify specific immune responses or deficiencies.

Quick summary

["IgG subclasses help diagnose immune disorders and guide treatment plans."]

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

Key facts at a glance

LOINC
13948-5
Short code
C immitis IgM Ser Ql IA
Synonyms
C immitis IgM Ser Ql IA
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 like frequent infections, autoimmune conditions, or if they suspect an immune system issue affecting IgG levels. It can also be used to monitor treatment progress for conditions like chronic infections or immune deficiencies.

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, let your provider know before the test.

What the Test Results Mean

IgG is divided into four subclasses (IgG1, IgG2, IgG3, IgG4). Abnormal levels can indicate immune system imbalances, such as low resistance to infections or overactive immune responses. Results are compared to standard ranges for your age and health status.

Common Conditions Linked to IgG Subclass Results

Low levels of certain IgG subclasses may be linked to recurrent infections, poor vaccine responses, or autoimmune diseases. High levels might suggest chronic inflammation or certain immune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Understanding IgG Subclasses

Short name

IgG Subclass Levels

Frequently asked questions

What does it mean if my IgG subclass levels are low?
Low levels of specific IgG subclasses can indicate an immune system that struggles to fight certain types of infections or vaccines. For example, low IgG2 may affect protection against bacterial infections, while low IgG4 could be linked to autoimmune conditions. Your provider will discuss findings in the context of your symptoms and medical history.
How often should I get this test?
The frequency depends on your health condition. If you have an ongoing immune disorder or are being treated for one, your provider may recommend regular monitoring. If this test is part of a routine checkup, it may not be repeated unless symptoms change.
Can lifestyle changes affect IgG subclass results?
While diet, exercise, and stress management can support overall immune health, IgG subclass levels are primarily influenced by immune system function. Changes in results are usually evaluated by your healthcare provider based on clinical context, not just lifestyle factors alone.
  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