Immunoglobulin G (IgG) Subclass Measurement (Serum or Plasma)
This test measures different types (subclasses) of Immunoglobulin G (IgG), the most common antibody in your blood. IgG helps fight infections and is important for long-term immunity.
["IgG subclasses help identify specific immune system functions or deficiencies."]
Key facts at a glance
- LOINC
- 22426-1
- Short code
- M pneumo IgG Titr Ser
- Synonyms
- M pneumo IgG Titr Ser
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 8
- Ref high
- 61
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82977
- SNOMED
- 3110003
- 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 with distinct roles in immunity. This test evaluates the levels of these subclasses in your blood, often using immunoassay methods to detect and quantify them.
Why Might You Need This Test?
Doctors may order IgG subclass testing to diagnose or monitor conditions like immune deficiencies, autoimmune diseases, infections, or certain cancers. It can also help assess immune responses after treatments like vaccines or chemotherapy.
Common Uses and Conditions
Conditions that may require IgG subclass testing include primary immunodeficiency diseases (e.g., selective IgA deficiency), autoimmune disorders (e.g., lupus, rheumatoid arthritis), chronic infections, or monitoring immune recovery post-transplant.
Sample Collection and Preparation
Blood is drawn from a vein, typically in your arm. The blood sample is processed into either serum (after clotting) or plasma (anticoagulated). This test is usually performed on fresh or stored serum/plasma samples.
Reference range
Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Subclass Testing
Frequently asked questions
IgG subclass levels can reveal specific immune system strengths or weaknesses. For example, low IgG2 levels might indicate trouble fighting certain bacteria, while high IgG4 could be linked to autoimmune conditions or allergic responses. Always discuss results with your healthcare provider.
What are the typical reference ranges for IgG subclasses?
How long does it take to get the results of 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