Serum Immunoglobulin G (IgG) concentration
This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections and plays a key role in long-term immunity.
["IgG helps fight infections and supports immune function."]
Key facts at a glance
- LOINC
- 40458-2
- Short code
- PT imm FVIII DP PPP
- Synonyms
- PT imm FVIII DP PPP
- Category
- chemistry
- Sample
- plasma
- Container
- Lavender-top (EDTA) or Green-top (Heparin)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- coag-tissue-factor-induced-factor-substitution-immediately-after-addition-of-factor-viii-depleted-plasma
- CPT
- 85610
- SNOMED
- 396252006
- 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 Is Done
Your healthcare provider may order this test to check for low or high levels of IgG, which can happen in conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses in patients with weakened immune systems, such as those with HIV/AIDS or after organ transplants.
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 blood, which usually causes only a brief pinch. If you’re nervous, let your provider know so they can help make you comfortable.
How the Test Results Are Interpreted
Results are compared to a general reference range for healthy adults. Low IgG levels may indicate an immune disorder, while very high levels could suggest conditions like multiple myeloma or chronic infections. Your provider will discuss the results in the context of your overall health.
Possible Causes of Abnormal Results
Low IgG levels can occur due to immune system disorders (e.g., common variable immunodeficiency), chronic illnesses (e.g., HIV), or medications that suppress the immune response. High IgG levels may be linked to overactive immune responses, such as in autoimmune diseases or certain cancers.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
IgG Level
Frequently asked questions
What does my IgG level tell me about my health?
Can I eat or drink before this test?
How long will it take to get my results?
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