Immunoglobulin G (IgG) in Serum or Plasma
This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps fight infections and is important for long-term immunity.
["IgG levels help assess immune function and detect potential deficiencies or excesses."]
Key facts at a glance
- LOINC
- 97980-7
- Short code
- Hazelnut (rCor a) 14 IgG4-mCnc
- Synonyms
- Hazelnut (rCor a) 14 IgG4-mCnc
- 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 IgG Measure?
IgG is a type of antibody produced by your immune system to protect against bacteria and viruses. It plays a key role in defending against infections and helping your body remember past illnesses. This test specifically measures the concentration of IgG in your blood, which can vary depending on your health status, immune response, and other factors.
Why Might You Need This Test?
Doctors may order an IgG test to evaluate immune function, diagnose conditions like immunodeficiency, monitor treatment for autoimmune diseases, or check for infections. It can also be used in newborns to assess early immune development or in individuals with chronic illnesses.
Common Reasons for Testing
Common reasons include diagnosing conditions like common variable immunodeficiency (CVID), checking immune response after vaccination, or monitoring immune-related diseases. It may also be used in research or specialized clinical settings to study antibody levels.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood. Wear comfortable clothing and plan to stay near the testing site for a short time. Inform your healthcare provider about any medications or health conditions that could affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
IgG Level
Frequently asked questions
How Low or High IgG Levels Can Affect Health?
What Are Typical IgG Reference Ranges?
Can IgG Levels Change with Age?
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