Immunoglobulin G (IgG) mass concentration in serum/plasma
This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps protect your body from infections and diseases.
["IgG levels help assess immune function and detect potential immune deficiencies or infections."]
Key facts at a glance
- LOINC
- 63090-5
- Short code
- BLGIGG
- Synonyms
- B-Lactoglob IgG-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red top tube with clot activator
- Units
- N/A
- Ref low
- 0.35
- Ref high
- 0.5
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (e.g., ELISA, Fluorescence Enzyme Immunoassay)
- CPT
- 86001
- Specimen volume
- 0.5-1 mL serum
- Stability
- Stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below for up to 3 months. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What Is Immunoglobulin G (IgG)?
IgG, or Immunoglobulin G, is the primary antibody in your blood that fights off infections. It’s produced by your immune system in response to pathogens like bacteria and viruses. IgG also plays a role in long-term immunity by helping your body remember past infections.
Why Might You Need This Test?
Your doctor may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It can also be used to monitor conditions like HIV, lupus, or other autoimmune diseases.
Preparation for the Test
No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, and you can resume normal activities afterward.
What to Expect During the Test
The blood sample will be taken from a vein in your arm. You might feel a slight pinch, but it usually doesn’t cause significant discomfort. The test itself takes only a few minutes, and you’ll be able to leave right after.
Reference range
Negative: <0.35 mg/L; Equivocal: 0.35-0.5 mg/L; Positive: >0.5 mg/L. Reference ranges vary by assay manufacturer and laboratory.N/A
No fasting required. Patient should be informed that results should be interpreted in conjunction with clinical history and other diagnostic findings.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
IgG Level
Frequently asked questions
Low IgG levels may indicate an immune deficiency, such as common variable immunodeficiency (CVID), where your body struggles to produce enough antibodies. High IgG levels can sometimes suggest chronic infections, autoimmune conditions, or exposure to certain medications.
How long does it take to get results from this test?
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