Total Immunoglobulin G (IgG) in Serum
This test measures the total amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections and diseases.
["IgG levels help assess your immune system’s strength and detect potential immune deficiencies or infections."]
Key facts at a glance
- LOINC
- 45224-3
- Short code
- M pneumo IgG Ser Ql IA
- Synonyms
- M pneumo IgG Ser Ql IA
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- 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
Why This Test Is Done
Your doctor may order this test to check for immune system disorders, such as low IgG levels that could make you more susceptible to infections. It may also be used to monitor immune responses in conditions like HIV, lupus, or after certain treatments like chemotherapy. Sometimes, it’s part of a broader evaluation for recurrent infections or unexplained fatigue.
What to Expect Before the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. If you’re nervous, let your healthcare provider know—they can help make the process more comfortable.
What the Results Mean
Results are compared to a general reference range for healthy adults. Very high or very low levels might signal underlying health concerns, but your doctor will interpret results in the context of your medical history and other tests.
Common Conditions Linked to IgG Levels
Low IgG levels can indicate conditions like Common Variable Immunodeficiency (CVID), where the immune system doesn’t produce enough antibodies. High IgG levels might be seen in chronic infections, autoimmune diseases, or certain cancers.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG levels play a critical role in immune defense, and abnormal results can signal immune dysfunction. Your doctor will discuss findings with you and may recommend further testing or treatments if needed.
Short name
IgG Level
Frequently asked questions
What causes IgG levels to be low?
How often should IgG levels be checked?
Does diet 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