Immunoglobulin G (IgG) in Serum, Mass Concentration
This test measures the amount of Immunoglobulin G (IgG), a type of antibody found in your blood serum. IgG helps protect your body from infections and is important for long-term immunity.
["IgG helps fight infections and supports long-term immunity by binding to pathogens."]
Key facts at a glance
- LOINC
- 86041-1
- Short code
- S pneum Da 2 IgG sp1 Ser-mCnc
- Synonyms
- S pneum Da 2 IgG sp1 Ser-mCnc
- Category
- coagulation
- 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 Is Immunoglobulin G (IgG)?
IgG is the most common type of antibody in your blood. Antibodies are proteins that help your immune system recognize and fight off harmful substances like bacteria and viruses. IgG is particularly important because it can cross the placenta to provide passive immunity to your baby during pregnancy and shortly after birth. It also remains in your body for a long time, providing ongoing protection against infections you’ve already encountered.
Why Might You Need This Test?
Doctors may order an IgG test to evaluate your immune system function. This could be done if you have symptoms of a weakened immune system, such as frequent infections, slow healing wounds, or unexplained fatigue. It may also be used to monitor conditions like autoimmune diseases, certain infections, or to check for immune deficiencies before or after treatments like chemotherapy.
When Could You Expect Results?
The results of your IgG test are typically available within a few days after your blood sample is drawn. Your healthcare provider will discuss the results with you and explain what they mean in the context of your health.
What Can Affect IgG Levels?
Several factors can influence IgG levels, including your overall health, immune status, diet, and certain medications. Chronic illnesses, infections, or autoimmune conditions can sometimes lead to lower IgG levels, while certain treatments or nutritional deficiencies may affect production.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG levels can provide important clues about your immune health. Low IgG levels may indicate an immune deficiency or a condition that affects antibody production, such as HIV/AIDS, certain cancers, or long-term use of immunosuppressive medications. High IgG levels might be seen in chronic infections, autoimmune diseases, or certain allergic reactions. Your doctor will use these results along with other factors to guide diagnosis and treatment.
Short name
IgG Level
Frequently asked questions
How is this test typically performed?
Will this test hurt?
Can I eat or drink before this test?
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.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy