Immunoassay for Immunoglobulin G (IgG) in Serum or Plasma
This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections and diseases.
["IgG levels help doctors assess immune function and diagnose conditions like low immunity or certain infections."]
Key facts at a glance
- LOINC
- 48997-1
- Short code
- IC IgG Fld C1Q Bind-mCnc
- Synonyms
- IC IgG Fld C1Q Bind-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- c-q-binding-assay
- 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 Might Be Ordered
Your doctor may recommend this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It could also be used to monitor immune responses during treatments like chemotherapy or if you have conditions like HIV, lupus, or other autoimmune diseases.
What to Expect Before the Test
No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw if your doctor specifies it, but this is not always required. Bring your medical records or any medications you’re currently taking.
What Happens During the Test
A healthcare provider will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample will be sent to a lab for analysis.
What the Results Mean
IgG levels vary depending on your health, age, and overall immune status. Your doctor will compare your results with your baseline or with standard reference ranges to determine if your levels are low, normal, or high. Low IgG levels may indicate an immune deficiency, while very high levels could suggest certain infections, chronic diseases, or overactive immune responses.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG is the most abundant antibody in your blood and plays a critical role in long-term immunity. Low IgG levels can lead to recurrent infections, delayed wound healing, or increased susceptibility to diseases like pneumonia or tuberculosis. Conversely, extremely high IgG levels may signal chronic infections, autoimmune disorders, or other systemic conditions. Monitoring IgG helps doctors diagnose and manage immune-related conditions effectively.
Short name
IgG Level
Frequently asked questions
What causes IgG levels to be low?
What are some common symptoms of low IgG?
How is IgG treated if it’s low?
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