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Immunoglobulin G (IgG) Subclass Quantification (Serum)

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

This test measures the amounts of different types (subclasses) of Immunoglobulin G antibodies in your blood serum. IgG is the most common antibody in your body and helps fight infections.

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
110679-8
Short code
Reticulin IgG Msmt Ser
Synonyms
Reticulin IgG Msmt Ser
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 Is Done

Doctors may order this test to evaluate immune function, diagnose conditions like hypogammaglobulinemia, or assess responses to treatments for autoimmune diseases or infections. It can also help monitor patients with certain genetic disorders or those receiving immune-modulating therapies.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into a vein in your arm to draw blood. This is usually done in a clinic or hospital lab. You might feel a slight pinch, but it should only take a few minutes.

What the Results Mean

Results show the concentration of IgG subclasses (IgG1, IgG2, IgG3, IgG4). While reference ranges vary by lab, lower levels of certain subclasses may indicate immune system issues, while higher levels might suggest overactive immune responses or certain diseases.

Common Conditions Affecting Results

Conditions that may affect IgG subclass levels include chronic infections, autoimmune diseases (like lupus or rheumatoid arthritis), certain genetic disorders (e.g., common variable immunodeficiency), or treatments that suppress the immune system.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG subclass levels

Frequently asked questions

What does it mean if my IgG subclass levels are abnormal?
Abnormal IgG subclass levels can signal an immune system disorder. For example, low IgG2 levels might suggest trouble fighting certain bacteria, while high IgG4 could be linked to allergic reactions or certain autoimmune conditions. Always discuss results with your healthcare provider for personalized interpretation.
How often should I get this test?
The frequency depends on your health condition and treatment plan. Your doctor may recommend this test periodically if you have an ongoing immune-related issue or are undergoing treatment that affects antibodies.
Can diet or lifestyle affect IgG subclass levels?
Diet and lifestyle factors like nutrition, stress, and infections can indirectly influence immune function but do not directly alter IgG subclass levels. Focus on maintaining a balanced diet and managing stress to support overall immune health.
  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