Serum/Plasma Substance Concentration for Immunoglobulin G (IgG) by Immunoassay
This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections and is important for long-term immunity.
["IgG levels help assess immune function and identify potential immune deficiencies or infections."]
Key facts at a glance
- LOINC
- 33565-3
- Short code
- ENA SM IgG Ser IB-aCnc
- Synonyms
- ENA SM IgG Ser IB-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ib
- 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 fight infections and diseases. IgG is particularly important because it can cross the placenta to protect a developing fetus and provides long-term immunity after an infection has cleared.
Why Might You Need This Test?
Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow healing wounds, or unexplained fatigue. It can also be used to monitor immune responses in conditions like autoimmune diseases or after certain treatments.
Sample Collection and Preparation
A blood sample is taken from a vein in your arm. The blood is then processed to separate the serum or plasma, which is sent to a lab for testing. This test does not require fasting.
What Does the Test Measure?
The test measures the concentration of IgG in your blood using an immunoassay method. This method detects the presence of IgG antibodies by identifying their specific binding to other substances.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low IgG levels may indicate an immune deficiency, where your body struggles to produce enough antibodies to fight infections. This can be due to genetic conditions, certain medications, or conditions like HIV/AIDS. High IgG levels can sometimes be seen in chronic infections, autoimmune diseases, or certain types of cancer, though this is less common and requires further evaluation.
Short name
IgG Level
Frequently asked questions
What are normal IgG levels?
How long does it take to get the results?
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.
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