Total Immunoglobulin G (IgG) Level
This blood test measures the amount of Immunoglobulin G (IgG), a key antibody in your immune system that helps fight infections and diseases.
["IgG helps protect your body against infections and supports long-term immunity."]
Key facts at a glance
- LOINC
- 57914-4
- Short code
- BLG-IgE
- Synonyms
- B-Lactoglob IgE/IgE total %
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube without anticoagulant
- Units
- N/A
- Ref low
- 0.35
- Ref high
- 0.7
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Immunoassay (Fluorescent Enzyme Immunoassay / FEIA)
- CPT
- 86003
- SNOMED
- 395128004
- Specimen volume
- 1.0 mL serum (minimum 0.5 mL)
- Stability
- Serum stable at room temperature for 8 hours; refrigerated at 2-8°C for 7 days; frozen at -20°C or below for up to 1 month. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It could also be used to monitor conditions like HIV, autoimmune diseases, or after receiving certain vaccines or treatments that affect immunity.
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. The process usually takes a few minutes, and you can resume normal activities afterward.
What the Results Mean
IgG levels can vary depending on your overall health, age, and medical conditions. Low IgG levels might suggest an immune deficiency, while very high levels could indicate certain immune system disorders or chronic infections. Your healthcare provider will interpret the results in the context of your health history and symptoms.
Common Conditions Monitored
This test is often used to diagnose or monitor conditions like HIV/AIDS, certain autoimmune diseases (e.g., lupus), chronic infections, or after receiving immunosuppressive therapies. It can also help assess immune function in people with congenital immune deficiencies.
Reference range
Class 0: <0.35 kU/L (Negative), Class 1: 0.35-0.70 kU/L (Low), Class 2: 0.71-3.50 kU/L (Moderate), Class 3: 3.51-17.50 kU/L (High), Class 4: 17.51-50.00 kU/L (Very High), Class 5: 50.01-100.00 kU/L (Very High), Class 6: >100.00 kU/L (Very High)N/A
No special patient preparation is required. Patient should inform their healthcare provider of any medications (especially antihistamines or corticosteroids) that may affect results. Avoid sample collection during active allergic episodes when possible for baseline evaluation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Total
Frequently asked questions
What causes IgG levels to be low?
How long does it take to get results?
Can diet 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