Immunoglobulin G (IgG) Subclass Measurement (Serum)
This test measures the levels of different subclasses of Immunoglobulin G (IgG), a key antibody protein in your blood. IgG subclasses help protect your body from infections and play roles in immune responses.
["IgG subclasses help identify immune system function and potential deficiencies or disorders."]
Key facts at a glance
- LOINC
- 47343-9
- Short code
- Deprecated S pneum43 IgG sp1 Ser IA-mCnc
- Synonyms
- Deprecated S pneum43 IgG sp1 Ser IA-mCnc
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- 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
What IgG Subclasses Does This Test Measure?
IgG is divided into four subclasses (IgG1, IgG2, IgG3, IgG4), each with distinct functions. This test evaluates the concentration of these subclasses in your serum. Variations in these levels can indicate immune system health, response to vaccines, or underlying conditions like immunodeficiency.
Why Might You Need This Test?
Doctors may order this test if you have symptoms of a weakened immune system, such as frequent infections, unusual bruising, or prolonged healing of wounds. It’s also used to assess immune responses after vaccination or to diagnose conditions like common variable immunodeficiency (CVID).
How Is the Test Performed?
A blood sample is drawn from a vein in your arm. The serum portion is then analyzed to measure IgG subclass levels using immunoassay techniques, which detect specific antibody proteins.
What Does the Test Result Mean?
Results show the concentration of each IgG subclass. Abnormal levels—either too high or too low—can signal immune system issues. Your healthcare provider will interpret the results in the context of your symptoms and medical history.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance: IgG Subclass Testing Plays a Critical Role in Diagnosing and Monitoring Immune-Related Disorders.
Short name
IgG Subclass Test
Frequently asked questions
What causes abnormal IgG subclass levels?
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