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Serum or plasma mass concentration of immunoglobulin G (IgG) subclasses (IgG1, IgG2, IgG3, IgG4)

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

This test measures the amount of different types of Immunoglobulin G (IgG), a key protein in your immune system, found in your blood.

Quick summary

["IgG helps fight infections and is important for long-term immunity."]

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

Key facts at a glance

LOINC
2463-8
Short code
M-IgE Ser-mCnc
Synonyms
M-IgE 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
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 doctor may recommend this test if they suspect an immune system disorder, such as a low or high level of specific IgG antibodies. It can also help diagnose or monitor conditions like immunodeficiency, autoimmune diseases, or certain infections.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into a vein in your arm to draw blood. If you’re nervous, let your healthcare provider know so they can help make it more comfortable.

What the Test Results Mean

Each IgG subclass has a different role in your immune system. Abnormal levels might indicate problems like reduced immunity, overactive immune responses, or other health issues. Your doctor will interpret the results in the context of your overall health and symptoms.

Common Conditions Monitored

This test is often used to monitor conditions like chronic infections, autoimmune diseases (such as lupus or rheumatoid arthritis), or congenital immunodeficiency disorders. It can also help track responses to treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG subclass levels

Frequently asked questions

What does an abnormal IgG subclass result mean?
An abnormal result could indicate an immune system issue, such as a deficiency in certain IgG types, which might make you more prone to infections. It could also suggest an overactive immune response, like in autoimmune diseases. Your doctor will discuss these findings with you based on your symptoms and medical history.
How often will I need this test?
The frequency depends on your condition and treatment plan. Some people need this test once a year, while others may require it more often if they have an ongoing health issue or are undergoing treatment.
Can diet or supplements affect IgG levels?
While diet and supplements can influence overall immune health, they typically do not directly affect IgG subclass levels. However, maintaining a balanced diet and good nutrition supports your immune system overall.
  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