Immunoglobulin G (IgG) in Serum
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 helps fight infections and supports long-term immunity."]
Key facts at a glance
- LOINC
- 47340-5
- Short code
- Deprecated S pneum34 IgG sp2 Ser IA-mCnc
- Synonyms
- Deprecated S pneum34 IgG sp2 Ser IA-mCnc
- Category
- coagulation
- 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
What Is Immunoglobulin G (IgG)?
IgG is the most common type of antibody in your blood. Antibodies are proteins that help your immune system recognize and fight off harmful substances like bacteria and viruses. IgG is particularly important for providing long-term immunity after you recover from an infection or receive a vaccine.
Why Might You Need This Test?
Doctors may order an IgG test to check for low or high levels, which can indicate conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses in patients with immune-related conditions.
Common Reasons for Testing
Common reasons include diagnosing or monitoring immune system disorders, assessing immune response after vaccination, evaluating chronic illnesses (e.g., HIV, hepatitis), or checking for signs of malnutrition or malabsorption.
What to Expect Before the Test
No special preparation is usually needed. You may have a small needle inserted into your arm to draw blood. If you’re nervous, let your healthcare provider know so they can help.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low IgG levels may suggest an immune deficiency, chronic infections, or conditions like celiac disease or malabsorption. High IgG levels can sometimes indicate chronic infections, autoimmune disorders, or certain cancers. Monitoring IgG levels helps guide treatment decisions for immune-related conditions.
Short name
IgG Level
Frequently asked questions
What does an abnormal IgG result mean?
How often should I get this test?
Can diet or lifestyle 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