Immunoglobulin G (IgG) Subclass 1, Serum
This test measures the amount of Immunoglobulin G (IgG) subclass 1 in your blood serum. IgG is a type of antibody that helps protect your body from infections.
["IgG1 antibodies play a key role in fighting bacteria and viruses, and their levels can vary depending on your immune response and health status."]
Key facts at a glance
- LOINC
- 107945-8
- Short code
- TIF1-gamma IgG Ser Ql IA
- Synonyms
- TIF1-gamma IgG Ser Ql IA
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- 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 Does This Test Measure?
IgG1 is one of five subclasses of Immunoglobulin G (IgG), the most abundant antibody in your blood. It is primarily involved in defending against bacterial and viral infections. Levels can be influenced by immune responses, chronic illnesses, or certain medications.
Why Might You Need This Test?
Doctors may order this test to evaluate immune function, diagnose or monitor conditions like autoimmune diseases, infections, or certain immune deficiencies. It can also help assess how your body is responding to treatments for conditions affecting the immune system.
Common Reasons for Testing
Common reasons include diagnosing or managing conditions such as chronic infections, autoimmune diseases (like rheumatoid arthritis or lupus), immune deficiencies, or evaluating immune responses to vaccines or treatments.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for a few hours before the blood draw, but this is not always required for this test. Bring any medications or supplements you are currently taking to your appointment.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal IgG1 levels may indicate an overactive or underactive immune response. High levels could suggest chronic infections, certain autoimmune diseases, or overproduction of antibodies. Low levels might be seen in immune deficiencies or certain chronic illnesses. This test can help guide treatment decisions and monitor disease progression.
Short name
IgG1 Level
Frequently asked questions
What are normal IgG1 levels?
How is this test performed?
Can IgG1 levels change over time?
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