Immunoglobulin G (IgG) Subclass 1, Serum or Plasma Mass Concentration
This test measures the amount of Immunoglobulin G (IgG) subclass 1, a type of antibody in your blood. IgG antibodies help protect your body from infections and diseases.
["IgG1 antibodies play a key role in immune defense; levels may vary with health status or immune response."]
Key facts at a glance
- LOINC
- 56523-4
- Short code
- IGF-I 15M p chal SerPl-mCnc
- Synonyms
- IGF-I 15M p chal SerPl-mCnc
- Category
- hormone
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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?
IgG1 is one of five subclasses of Immunoglobulin G (IgG), the most common antibody in your blood. This subclass is particularly important for fighting bacterial and viral infections. Your body produces IgG1 in response to vaccines, infections, or chronic illnesses. Levels can help assess immune function, especially in conditions like autoimmune diseases or immune deficiencies.
Why Might You Need This Test?
Your healthcare provider may order this test if you have symptoms of an immune disorder, such as frequent infections, fatigue, or unexplained illnesses. It may also be used to monitor immune responses after vaccination, diagnose certain autoimmune conditions, or evaluate immune system function in people with chronic diseases.
Sample Collection and Preparation
A blood sample is taken from a vein in your arm. The blood is sent to a lab where it is processed to separate serum or plasma. The IgG1 level is then measured using a specialized immunoassay technique to detect and quantify the antibody.
What to Expect Before the Test
No special preparation is needed for this test. You may have a small bandage or bruise at the injection site afterward. If you are on blood-thinning medication, let your provider know before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG1 Subclass Level
Frequently asked questions
IgG1 levels can be lower in people with immune deficiencies, such as severe combined immunodeficiency (SCID) or certain genetic disorders. Elevated levels may be seen in chronic infections, autoimmune diseases, or after vaccination. Monitoring IgG1 subclass levels can help diagnose or manage conditions affecting immune function.
How are IgG1 levels typically interpreted?
What conditions might affect IgG1 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