Immunoassay for Immunoglobulin G (IgG) Subclass 1 (IgG1) in Serum or Plasma
This test measures the level of Immunoglobulin G1 (IgG1), one of the types of antibodies in your blood. IgG1 plays a key role in defending against infections and diseases.
["IgG1 helps fight infections and supports immune response; levels may vary with health conditions or immune responses."]
Key facts at a glance
- LOINC
- 73282-6
- Short code
- MTX ind plt IgM SerPl Ql FC
- Synonyms
- MTX ind plt IgM SerPl Ql FC
- Category
- hematology
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- flow-cytometry
- 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 Is Immunoglobulin G1 (IgG1)?
IgG1 is a subtype of Immunoglobulin G (IgG), the most common antibody in your blood. It is part of the immune system’s defense against bacteria, viruses, and toxins. Your body produces IgG1 to help neutralize pathogens and mark them for destruction by other immune cells. Levels of IgG1 can change depending on your immune response, health status, or certain medical conditions.
Why Might You Need This Test?
Doctors may order this test to evaluate immune function, diagnose or monitor conditions affecting antibody production, or assess responses to treatments like vaccines or medications. It can also help identify immune deficiencies or autoimmune disorders.
When Is This Test Performed?
This test is often performed when doctors suspect an immune-related issue, such as a low antibody response after vaccination, chronic infections, or conditions like lupus or rheumatoid arthritis. It may also be used in research or specialized clinical settings to study immune responses.
Sample Collection and Preparation
A blood sample is drawn from a vein in your arm. The blood is processed to separate serum or plasma, which is then sent to a lab for testing. This process is quick and typically done in a doctor’s office or clinic.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal IgG1 levels may indicate underlying immune system dysfunction. For example, very low IgG1 could suggest a primary immunodeficiency, while very high levels might be seen in chronic infections, certain autoimmune diseases, or overactive immune responses. Monitoring IgG1 subclass levels can help guide treatment decisions, especially in patients receiving immune-modulating therapies.
Short name
IgG1 Subclass Measurement
Frequently asked questions
What does a low IgG1 level mean?
What causes changes in IgG1 levels?
Is this test painful?
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