Serum Immunoglobulin G (IgG) concentration
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 helps fight infections and supports long-term immunity."]
Key facts at a glance
- LOINC
- 77211-1
- Short code
- CA6IgA
- Synonyms
- CA6 IgA Ser IA-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube without anticoagulant
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay
- CPT
- 83520 (Immunoassay for analyte other than infectious agent antibody, quantitative, not otherwise specified)
- Specimen volume
- 1 mL serum (minimum 0.5 mL)
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–168 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 harmful substances like bacteria and viruses. IgG is particularly important for providing long-term protection against infections.
Why Might You Need This Test?
Your doctor may order an IgG test to check for low or high levels, which can indicate conditions like immune deficiencies, certain infections, or autoimmune diseases. It’s also used in monitoring treatments for conditions affecting the immune system.
When Is an IgG Test Performed?
This test is often done when you have symptoms of weakened immunity, such as frequent infections, slow healing wounds, or unexplained fatigue. It may also be part of routine testing for certain medical conditions or before receiving certain vaccines or treatments.
What Does the Test Involve?
A blood sample is taken from a vein in your arm. The blood is then sent to a lab, where it is analyzed to measure the concentration of IgG antibodies. The results help determine if your immune system is functioning as expected.
Reference range
Reference values are laboratory-specific; consult your reporting laboratory for established reference ranges. Results should be interpreted in conjunction with clinical findings and other diagnostic parameters.N/A
No special patient preparation is required. Fasting is not necessary prior to specimen collection for this test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low IgG levels may suggest an immune deficiency, such as common variable immunodeficiency (CVID), which can make you more prone to infections. High IgG levels might be seen in chronic infections, autoimmune diseases, or certain types of cancer. Your doctor will interpret the results in the context of your overall health and symptoms.
Short name
IgG Level
Frequently asked questions
What Are Normal IgG Levels?
How Long Does It Take to Get Results?
Can I Eat or Drink Before the 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