Serum or plasma mass concentration of immunoglobulin G (IgG) subtypes (e.g., IgG1, IgG2, IgG3, IgG4)
This test measures the amount of specific types of antibodies (IgG subclasses) in your blood. These antibodies help fight infections and support immune function.
["Understanding your IgG subclass levels can help identify immune system strengths or weaknesses."]
Key facts at a glance
- LOINC
- 39533-5
- Short code
- DO-Hgb Bld-mCnc
- Synonyms
- DO-Hgb Bld-mCnc
- Category
- hematology
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 12
- Ref high
- 17.5
- Critical range
- 7 N/A – 20 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 85018
- SNOMED
- 900000000000003004
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms of an immune disorder, such as frequent infections, autoimmune conditions, or if you’re being evaluated for conditions like chronic infections, allergies, or certain cancers. It can also be used to monitor treatment responses in patients with immune-related diseases.
What to Expect Before the Test
No special preparation is usually needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re taking blood from your home, ensure you follow your healthcare provider’s instructions for safety and comfort.
How the Test Results Are Used
Results help determine if your immune system is producing the right balance of IgG antibodies. Low or high levels of certain IgG subclasses may indicate underlying health issues that need further evaluation or treatment.
Common Conditions Linked to IgG Subclass Testing
IgG subclass testing is often linked to conditions like recurrent sinus or respiratory infections, chronic diarrhea, autoimmune diseases (e.g., rheumatoid arthritis), or certain immune deficiencies. It can also play a role in assessing antibody responses to vaccines or treatments.
Reference range
Adult males: 13.5-17.5 g/dL; Females: 12.0-16.0 g/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG subclass testing is critical for diagnosing and managing immune-related disorders. For example, low IgG2 levels may suggest trouble fighting certain bacterial infections, while elevated IgG4 could be associated with certain autoimmune conditions or allergic reactions. Regular monitoring helps tailor treatments to your specific immune needs.
Short name
IgG subclass levels
Frequently asked questions
What does a low or high IgG subclass level mean?
How often should I get this test?
Can lifestyle changes 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