Immunoglobulin G (IgG) Subclass Concentration (Serum/Plasma)
This test measures the levels of different subclasses of Immunoglobulin G (IgG), a key antibody in your immune system. IgG subclasses help protect against bacteria, viruses, and toxins.
["IgG subclasses play a vital role in immune defense and can be checked if you have symptoms of immune system issues or certain conditions."]
Key facts at a glance
- LOINC
- 2464-6
- Short code
- IgG CSF-mCnc
- Synonyms
- IgG CSF-mCnc
- Category
- chemistry
- Sample
- csf
- Container
- Sterile tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82784
- Specimen volume
- 1-2 mL
- Stability
- Immediate analysis required, Refrigerated: 1h
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
What Does This Test Measure?
IgG is divided into four subclasses (IgG1, IgG2, IgG3, IgG4), each with distinct roles in immunity. This test quantifies the concentration of these subclasses in your blood. Variations can indicate immune dysfunction, infections, or autoimmune diseases.
Why Might You Need This Test?
Doctors may order this test if you have symptoms like frequent infections, unusual fatigue, or if you’re being evaluated for conditions like immunodeficiency, autoimmune disorders, or certain cancers. It can also help monitor treatment responses in immune-related illnesses.
Common Reasons for Testing
Common reasons include diagnosing or monitoring immune system disorders, assessing immune function in people with chronic illnesses, or evaluating responses to treatments like chemotherapy or biologics that target antibodies.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate serum or plasma for testing. No special preparation is needed, but fasting may be required depending on the clinical context.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Subclass Levels
Frequently asked questions
IgG subclass levels can provide insights into immune health. Low levels in certain subclasses may suggest immune deficiencies, while elevated levels could indicate chronic infections, autoimmune diseases, or certain medications that suppress the immune system. Monitoring these levels helps tailor treatments to your specific needs.
Low levels of specific IgG subclasses might indicate an impaired ability to fight certain types of infections or autoimmune reactions. High levels could be due to chronic illnesses, overactive immune responses, or certain treatments. Your doctor will interpret results in the context of your overall health and symptoms.
Test results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the results with you during your follow-up visit.
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