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Immunoglobulin G (IgG) Subclass Measurement (Serum)

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

This test measures specific types of antibodies called immunoglobulin G (IgG) subclasses in your blood serum. IgG is the most common type of antibody and plays a key role in defending against infections and diseases.

Quick summary

["IgG subclasses 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
109961-3
Short code
CV2 IgG Msmt Ser
Synonyms
CV2 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 Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like frequent infections, unexplained fatigue, or if you have conditions such as autoimmune diseases, certain cancers, or immune system disorders. It may also be used to monitor treatment responses in patients with known immune-related conditions.

What to Expect During the Test

A small amount of blood is drawn from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis.

Preparation and Care

No special preparation is needed for this test. However, inform your healthcare provider about any medications you are taking, as some may affect your results. Avoid strenuous activity before the blood draw if advised by your provider.

What the Results Mean

Results show the concentration of IgG subclasses (IgG1, IgG2, IgG3, and IgG4). Abnormal levels can indicate immune system issues, such as low or high antibody production, which may require further medical evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG subclass testing is critical for diagnosing and managing conditions affecting the immune system. For example, low levels of certain subclasses may suggest immune deficiencies, while elevated levels could be linked to autoimmune diseases or chronic infections. This test helps tailor treatments to address specific immune dysfunctions.

Short name

IgG subclass levels

Frequently asked questions

What causes IgG subclass levels to be checked?
IgG subclass levels are checked if you have symptoms like repeated infections, unusual fatigue, or if you have a known condition that affects your immune system, such as HIV, lupus, or certain cancers. It may also be part of routine monitoring for patients on immune-suppressing treatments.
How do IgG subclass results affect my treatment?
If your IgG subclass results are abnormal, your healthcare provider may recommend additional tests or treatments to address the underlying issue. For instance, if low levels are found, they might suggest immune-boosting therapies or further diagnostic evaluations.
Can diet or lifestyle changes impact IgG subclass results?
While diet and lifestyle factors can influence overall immune health, IgG subclass levels are primarily determined by your body’s immune response. However, maintaining a balanced diet rich in vitamins and minerals can support general immune function, though it may not directly alter 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