Serum Immunoglobulin Subclass (IgG1, IgG2, IgG3, IgG4) Profile
This test measures the levels of different types of Immunoglobulin G (IgG), a key antibody protein in your immune system. IgG subclasses help the body fight infections and regulate immune responses.
["Understanding your IgG subclass levels can help identify immune system strengths or weaknesses."]
Key facts at a glance
- LOINC
- 24914-4
- Short code
- MR Sinuses
- Synonyms
- MR Sinuses
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- mr
- 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, autoimmune conditions, or if you’re being treated for a condition that affects your immune system. It could also be part of a broader evaluation for chronic diseases or before certain immunizations.
What to Expect Before the Test
No special preparation is needed. You’ll likely have blood drawn from a vein in your arm. If you’re on blood thinners, let your provider know before the test.
What the Results Mean
IgG subclasses work together to support immunity, but individual levels can vary. Low levels of certain subclasses might suggest immune dysfunction, while high levels could indicate chronic inflammation or other conditions. Your provider will interpret results in the context of your overall health.
Common Conditions Monitored
This test helps diagnose or monitor conditions like chronic infections, certain autoimmune diseases (e.g., lupus, rheumatoid arthritis), or immune deficiencies. It may also be used to assess how well your immune system responds to treatments.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: IgG subclasses play a critical role in immune defense. Abnormal levels may indicate immune system imbalances, chronic infections, or conditions requiring targeted treatment adjustments. Always discuss results with your healthcare provider.
Short name
IgG Subclass Levels
Frequently asked questions
What causes IgG subclass levels to change?
How often should I get this test?
Can diet or lifestyle affect IgG subclass levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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