Immunoglobulin G (IgG) Subclass 1 (IgG1) in Serum/Plasma
This test measures the amount of a specific type of antibody (IgG1) in your blood, which plays a key role in fighting infections and supporting immune responses.
["IgG1 helps identify immune function and potential deficiencies in antibody production."]
Key facts at a glance
- LOINC
- 34925-8
- Short code
- Imm Moncytes NFr Bld
- Synonyms
- Imm Moncytes NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What Is IgG1 Used For?
IgG1 levels are often checked to evaluate immune system health, especially in conditions like immunodeficiency, autoimmune diseases, or after certain treatments that may affect antibody production. It may also be used to monitor immune responses to vaccines or infections.
How Is This Test Performed?
A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate serum or plasma, where the IgG1 antibody is measured using an immunoassay method. This test is usually done in a lab and results are available within a few days.
Why Might You Need This Test?
Your healthcare provider may order this test if you have symptoms of a weakened immune system (such as frequent infections), if you’re being treated for an autoimmune condition, or if you’re receiving therapies that could impact antibody levels.
What Do Results Mean?
Results are compared to a general reference range for healthy individuals. Low IgG1 levels may suggest immune dysfunction, while very high levels could indicate chronic inflammation or certain immune disorders. Always discuss results with your doctor.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG1 is one of the main subclasses of immunoglobulin G (IgG), which is the most abundant antibody in the blood. Low IgG1 levels can indicate problems with immune function, such as primary immunodeficiency diseases or conditions where the immune system is suppressed (e.g., HIV/AIDS). Conversely, elevated IgG1 may be associated with chronic inflammation, certain infections, or autoimmune responses. Monitoring IgG1 can help guide treatment decisions for patients with immune-related conditions.
Short name
IgG1 Level
Frequently asked questions
What causes IgG1 levels to change?
Results from this test are typically available within 2–5 business days, depending on lab processing times. Your healthcare provider will contact you once results are ready.
No fasting is required for this blood test. You can eat and drink normally before your appointment unless instructed otherwise by your provider.
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