Serum/plasma immunoglobulin G (IgG) concentration
This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps protect your body from infections and plays a role in immune response.
["IgG levels help assess your immune system’s strength and identify potential deficiencies."]
Key facts at a glance
- LOINC
- 43101-5
- Short code
- PS IgA+IgG+IgM Pnl Ser
- Synonyms
- PS IgA+IgG+IgM Pnl Ser
- Category
- chemistry
- 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 a type of protein (antibody) produced by your immune system to fight infections. It’s the most abundant antibody in your blood and helps your body remember past infections to fight them faster if you get sick again. This test checks how much IgG is present in your serum or plasma.
Why Might You Need This Test?
Your doctor may order this test if you have symptoms like frequent infections, slow wound healing, or if you’re at higher risk for infections due to conditions like HIV, cancer treatments, or certain immune disorders.
Common Reasons for Testing
Common reasons include diagnosing or monitoring immune system disorders, evaluating symptoms of recurrent infections, or checking for immune deficiencies before certain treatments (e.g., chemotherapy).
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum (liquid part without clots) or plasma (liquid with clots) for testing. This test is typically done using an immunoassay method to detect IgG levels accurately.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Level
Frequently asked questions
IgG levels can indicate whether your immune system is functioning normally. Low levels may suggest immune deficiencies, while very high levels could be linked to certain autoimmune diseases or chronic infections. Monitoring IgG is especially important for people undergoing treatments that weaken the immune system.
Normal IgG levels vary by age and health status. Your doctor will compare your results to what’s expected for your age and overall health. If results are outside the expected range, further tests or evaluation may be needed.
While diet and lifestyle can influence overall immune health, IgG levels are primarily determined by your immune system’s response. Certain foods rich in vitamins (like vitamin D and zinc) may support immune function, but they don’t directly change 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