Immunoassay for Immunoglobulin G (IgG) Subclass 1 (IgG1) in Serum
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 is often evaluated when immune function or specific antibody responses are suspected.
["IgG1 helps your immune system fight infections and is important for long-term immunity."]
Key facts at a glance
- LOINC
- 7776-8
- Short code
- Whitefish IgG Qn
- Synonyms
- Whitefish IgG Qn
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 a subclass of Immunoglobulin G (IgG), the most common type of antibody in your blood. Antibodies are proteins that help your immune system recognize and neutralize foreign substances like bacteria and viruses. IgG1 is particularly involved in responding to certain infections and allergies. This test specifically looks at the concentration of IgG1 antibodies in your serum (liquid part of blood).
Why Might You Need This Test?
Your doctor may order this test if they suspect an immune-related condition, such as an infection, autoimmune disease, or a condition affecting antibody production. It can also be part of diagnosing or monitoring conditions like HIV, certain allergies, or immune deficiencies. Sometimes, it’s used to check how well your immune system is responding to treatments for diseases like lupus or rheumatoid arthritis.
What to Expect Before the Test
No special preparation is usually needed for this test. You will have a small needle inserted into your arm to draw a blood sample. This process is quick and typically causes only minor discomfort. If you are on blood-thinning medications or have a history of bleeding issues, let your doctor know beforehand.
What to Expect During the Test
The blood sample will be sent to a lab for analysis using an immunoassay method, which detects the presence and amount of IgG1 antibodies in your serum. The results are usually available within a few days, depending on your healthcare provider’s lab processes.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
IgG1 Subclass Test
Frequently asked questions
IgG1 levels can be lower in people with certain immune deficiencies, such as severe combined immunodeficiency (SCID) or HIV/AIDS, where the immune system is weakened. Elevated levels may be seen in chronic infections, certain autoimmune diseases, or allergic reactions. Monitoring IgG1 can help track immune function, response to treatments, or progression of certain conditions.
Results from this test are usually available within 2 to 5 business days, depending on your healthcare provider’s lab workflow. Your doctor will contact you once the results are ready, so keep their office information handy during your visit.
An abnormal IgG1 level may suggest an underlying immune issue, such as an infection, autoimmune disease, or an immune deficiency. Your doctor will interpret the results in the context of your medical history, symptoms, and other test results to determine the next steps. They may recommend further testing or adjustments to your treatment plan if needed.
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