Immunoglobulin G (IgG) in Serum or Plasma
This test measures the amount of Immunoglobulin G (IgG), a type of antibody found in your blood. IgG helps protect your body from infections and is the most common antibody in the immune system.
["IgG helps fight infections and supports long-term immunity."]
Key facts at a glance
- LOINC
- 102328-2
- Short code
- Goat Milk IgE RAST
- Synonyms
- Goat Milk IgE RAST
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- rast
- CPT
- 84484
- SNOMED
- 302774002
- 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 healthcare provider may order an IgG test to check for low or high levels, which can occur due to immune system issues, certain medical conditions, or after treatments like chemotherapy. It may also be used to monitor immune response during recovery or after vaccination.
What to Expect Before the Test
No special preparation is needed for this test. You may have blood drawn from a vein in your arm, or if testing urine or saliva, follow any specific instructions your provider gives you. The process is quick and usually painless.
What the Results Mean
Results are compared to standard reference ranges for IgG levels. Low IgG levels might indicate weakened immunity, while very high levels could suggest certain immune disorders or chronic infections. Your provider will interpret the results in the context of your overall health.
Common Conditions Affecting IgG Levels
IgG levels can be affected by conditions like HIV/AIDS, certain autoimmune diseases (e.g., lupus), chronic infections, or after treatments that suppress the immune system. Pregnancy, malnutrition, or certain medications can also influence IgG levels.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Level
Frequently asked questions
What questions might you have about this test?
How long will it take to get my results?
Can I eat or drink before this test?
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 17, 2026. · Read our editorial policy