Immunoglobulin G (IgG) in Serum, Mass 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 the most common type of antibody.
["IgG antibodies play a key role in long-term immunity and are often checked if you have recurring infections or immune-related conditions."]
Key facts at a glance
- LOINC
- 47495-7
- Short code
- Deprecated S pneum34 IgG sp1 Ser-mCnc
- Synonyms
- Deprecated S pneum34 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 IgG Antibodies Do in Your Body
IgG antibodies are part of your immune system’s defense. They help fight off bacteria and viruses by marking them for destruction by other immune cells. IgG is also found in breast milk, providing passive immunity to newborns. Levels of IgG can vary depending on your health, immune response, and exposure to infections.
Why Your Doctor Might Order This Test
Doctors may order an IgG test to diagnose or monitor conditions like immunodeficiency, autoimmune diseases, or infections. It can also help assess immune response after vaccination or treatment for infections.
Common Conditions Affecting IgG Levels
Low IgG levels may suggest a weakened immune system, potentially due to conditions like HIV/AIDS, certain cancers, or congenital immune deficiencies. High IgG levels can sometimes indicate chronic infections, inflammatory diseases, or overactive immune responses.
What to Expect During the Test
A blood sample is taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The sample is sent to a lab for testing.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG levels are critical for diagnosing and managing immune-related disorders. Abnormally low IgG can lead to frequent infections, while elevated levels may signal chronic inflammation or immune system overactivity. Monitoring IgG helps guide treatment plans for conditions like lupus, rheumatoid arthritis, or immune deficiencies.
Short name
IgG Level
Frequently asked questions
How often should I expect this test?
What do my IgG results mean?
Can diet or lifestyle affect IgG levels?
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