Immunoglobulin G (IgG) in Serum – Mass Concentration
This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG is the most common antibody in the body and plays a key role in protecting against infections.
["IgG helps fight infections and supports long-term immunity."]
Key facts at a glance
- LOINC
- 30494-9
- Short code
- Deprecated S pneum23 IgG sp1 Ser-mCnc
- Synonyms
- Deprecated S pneum23 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 Does This Test Measure?
IgG is the primary antibody produced by your immune system in response to infections, vaccines, and other immune challenges. It circulates in your bloodstream and provides broad protection against pathogens like bacteria and viruses. This test helps assess your overall immune function and identify potential deficiencies.
Why Might You Need This Test?
Doctors may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or recurrent illnesses. It can also be used to monitor immune responses after treatments like chemotherapy or bone marrow transplants.
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 to Expect After the Test
After the blood is drawn, you may feel a slight pinch or bruising at the site. Apply gentle pressure to stop any bleeding. Most people return to normal activities immediately. If you experience excessive bruising or pain, contact your provider.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low IgG levels may indicate an immune deficiency, such as common variable immunodeficiency (CVID) or other congenital or acquired immune disorders. High IgG levels can sometimes signal chronic infections, autoimmune conditions, or certain cancers. Monitoring IgG helps guide treatment decisions for immune-related conditions.
Short name
IgG Level
Frequently asked questions
What causes low IgG levels?
What are the symptoms of low IgG?
How is IgG tested?
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