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

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

This test measures the levels of different subclasses of Immunoglobulin G (IgG), a type of antibody in your blood. IgG is the most common antibody and plays a key role in fighting infections.

Quick summary

["IgG subclasses help identify specific immune responses and potential immune system imbalances."]

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

Key facts at a glance

LOINC
74862-4
Short code
IgG Kappa SerPl-mCnc
Synonyms
IgG Kappa 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

What IgG Subclasses Are Measured?

IgG antibodies are divided into four subclasses (IgG1, IgG2, IgG3, IgG4), each with distinct roles in immunity. This test typically evaluates the concentration of these subclasses in your serum or plasma to assess immune function and detect abnormalities.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms like recurrent infections, autoimmune diseases, or conditions affecting antibody production. It can also help diagnose or monitor certain immune disorders, such as hypogammaglobulinemia or immune deficiencies.

Sample Collection and Preparation

A blood sample is drawn from a vein in your arm. The blood is processed to separate serum or plasma, which is then analyzed for IgG subclass levels using immunoassay techniques.

What Do Results Mean?

Results show the concentration of each IgG subclass. While reference ranges vary by lab, abnormal levels may indicate immune system dysfunction, such as low IgG subclasses (hypogammaglobulinemia) or high levels in certain autoimmune conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: IgG Subclass Testing Helps Diagnose and Monitor Conditions Like

Short name

IgG subclass levels

Frequently asked questions

How long does it take to get results from this test?
Results are typically available within 1 to 3 business days, depending on lab processing times. Your healthcare provider will discuss the results with you during your follow-up visit.
What does it mean if my IgG subclass levels are low?
Low IgG subclass levels may suggest an immune deficiency, such as a primary antibody disorder or compromised immune function. This could increase your risk of frequent infections and may require further evaluation or treatment, such as immunoglobulin therapy.
Can lifestyle changes affect IgG subclass test results?
Lifestyle factors like diet, stress, or certain medications may influence immune function indirectly, but they typically do not alter IgG subclass test results directly. Always discuss any medications or lifestyle changes with your provider before testing.
  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