Skip to content

Immunoglobulin G Subclass 1, 2, 3, or 4 Quantification (Serum)

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

This test measures the specific types (subclasses) of Immunoglobulin G (IgG), a key antibody in your immune system. IgG subclasses help protect against infections and regulate immune responses.

Quick summary

["Understanding your IgG subclass levels can help identify immune system strengths or weaknesses."]

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

Key facts at a glance

LOINC
47289-4
Short code
IgG+IgG subclass Pnl Ser-mCnc
Synonyms
IgG+IgG subclass Pnl Ser-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 Matters

IgG antibodies are divided into four subclasses (IgG1, IgG2, IgG3, IgG4), each with different roles in immunity. Low levels of certain subclasses may suggest immune deficiencies, while high levels could indicate chronic inflammation or autoimmune conditions. This test helps doctors assess immune function, especially in patients with recurrent infections, autoimmune diseases, or immune-related disorders.

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. The sample will be sent to a lab for analysis. Results are typically available within a few days.

What the Results Mean

Results show the concentration of each IgG subclass in your serum. While reference ranges vary by lab, doctors compare your results to your own baseline or to known standards for your age and health status. Abnormal levels may prompt further testing or treatment adjustments.

Common Reasons for Testing

Doctors may order this test if you have frequent infections, autoimmune diseases (like rheumatoid arthritis), or conditions affecting immune function. It can also be used to monitor treatment responses in patients on immune-modulating therapies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Subclass Levels

Frequently asked questions

What does a low IgG subclass level mean?
A low level of a specific IgG subclass may suggest an immune deficiency, where your body struggles to produce enough of that type of antibody. This could increase your risk of infections, especially those targeted by that subclass. Your doctor may recommend additional tests or treatments to support your immune system.
How long does it take to get test results?
Test results are usually available within 3 to 5 business days, depending on your lab’s processing time. Your healthcare provider will contact you once results are ready, so check with them for updates if needed.
Can lifestyle changes affect IgG subclass levels?
While diet, exercise, and stress management can generally support immune health, they may not directly alter IgG subclass levels. However, maintaining a balanced lifestyle can help your overall immune function, which may indirectly influence antibody 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