Immunoglobulin G (IgG) Subclass Measurement in Serum (Quantitative)
This test measures the levels of specific subclasses of Immunoglobulin G (IgG), a type of antibody in your blood. IgG is the most common antibody and helps protect your body from infections.
["IgG subclasses help identify immune responses and potential deficiencies that may affect your health."]
Key facts at a glance
- LOINC
- 88185-4
- Short code
- IgG+IgM.porcine Ser Fetus Ql ID
- Synonyms
- IgG+IgM.porcine Ser Fetus Ql ID
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- immune-diffusion
- CPT
- 86430
- 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 Does This Test Measure?
IgG is divided into four subclasses (IgG1, IgG2, IgG3, IgG4), each playing a role in immune function. This test quantifies the concentration of one or more of these subclasses in your serum. These subclasses can vary in their effectiveness against different types of pathogens, such as bacteria, viruses, and toxins.
Why Might You Need This Test?
Doctors may order this test if you have symptoms like frequent infections, immune system disorders, or if you’re being evaluated for conditions like common variable immunodeficiency (CVID) or other antibody-related issues. It can also help monitor treatment responses in certain immune-related conditions.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate the serum (the liquid part without blood cells), which is then tested for IgG subclass levels. This test is typically done using a sensitive immunoassay method to detect and measure the antibody concentrations accurately.
Common Reasons for Testing
Common reasons include diagnosing or monitoring immune system disorders, assessing immune responses to infections or vaccines, or evaluating conditions where antibody levels or functions are suspected to be abnormal.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal IgG subclass levels can indicate underlying immune deficiencies, autoimmune diseases, or other conditions affecting antibody production or function. For example, low levels of certain subclasses may suggest a weakened ability to fight specific types of infections, while high levels might be associated with certain autoimmune conditions or overactive immune responses.
Short name
IgG Subclass Levels
Frequently asked questions
What does a low or high IgG subclass result mean?
How often should I get this test?
Can I eat or drink before this test?
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