Serum Immunoglobulin G (IgG) concentration
This test measures the amount of Immunoglobulin G (IgG) in your blood. IgG is a type of antibody that helps your immune system fight infections and diseases.
["IgG helps protect your body against bacteria and viruses."]
Key facts at a glance
- LOINC
- 112201-9
- Short code
- Sheep Milk IgE Qn IA
- Synonyms
- Sheep Milk IgE Qn IA
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- ia
- 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 most common type of antibody in your blood. It plays a key role in defending against infections and chronic diseases. This test helps doctors assess your immune system’s ability to produce antibodies, which can be important for diagnosing or monitoring conditions like immune deficiencies, infections, or certain autoimmune diseases.
Why Might You Need This Test?
Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, unusual bruising, or prolonged healing of wounds. It can also be used to monitor immune-related conditions or check for immune responses after vaccination.
What to Expect Before the Test
No special preparation is usually needed for this blood test. You may be asked to fast for a few hours before the test if your doctor specifies it, but this is not always required for IgG levels. Bring a list of medications you’re taking to your appointment.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm using a small needle. The process is quick and typically causes only minor discomfort. The blood sample will be sent to a lab for analysis.
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), which increases susceptibility to infections. High IgG levels can sometimes suggest chronic inflammation, autoimmune conditions, or certain types of cancer. Monitoring IgG levels helps guide treatment decisions and manage long-term health risks.
Short name
IgG Level
Frequently asked questions
What Are Normal IgG Levels?
How Long Does It Take to Get Results?
Can Diet or Medications 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