Serum Immunoglobulin G (IgG) Level
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 detect potential deficiencies or abnormalities."]
Key facts at a glance
- LOINC
- 109042-2
- Short code
- S pneum Da 6A IgG Msmt Ser
- Synonyms
- S pneum Da 6A IgG Msmt Ser
- 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 Does IgG Measure?
IgG is the most common type of antibody in your blood. It plays a key role in fighting off infections by helping your immune system recognize and remember pathogens like bacteria and viruses. IgG also helps transfer immunity from mother to baby during pregnancy.
Why Might You Need This Test?
Doctors may order an IgG test to check for immune system issues, such as low levels that could indicate conditions like HIV, certain cancers, or autoimmune diseases. It may also be used to monitor immune responses after vaccination or treatment for infections.
Sample Collection and Preparation
This test requires a blood sample drawn from a vein in your arm. After drawing blood, it is sent to a lab where it is processed to separate the serum (the liquid part without clots). The serum is then analyzed to measure IgG levels.
What to Expect Before the Test
No special preparation is needed for this test. You can eat and drink normally on the day of your appointment. If you are on blood-thinning medication, let your healthcare provider know before the test.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low IgG levels may suggest an immune deficiency, chronic illness, or conditions like celiac disease or malabsorption syndromes. High IgG levels can sometimes indicate chronic infections, inflammatory conditions, or certain cancers. Monitoring IgG levels helps guide treatment decisions and manage long-term health.
Short name
IgG Level
Frequently asked questions
How long does it take to get results?
What does a low IgG level mean?
Can IgG levels change over time?
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