IgG Substance Concentration in Serum (Qualitative or Quantitative)
This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps fight infections and is important for long-term immunity.
["IgG levels help assess immune function and detect potential deficiencies or excesses."]
Key facts at a glance
- LOINC
- 27113-0
- Short code
- Deprecated S pneum8 IgG Ser-mCnc
- Synonyms
- Deprecated S pneum8 IgG Ser-mCnc
- Category
- coagulation
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 82784
- 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 IgG Tests Measure
IgG is the primary antibody produced by your immune system to defend against bacteria and viruses. This test evaluates its concentration in your blood, which can vary based on health conditions, immune responses, or genetic factors.
Why Your Doctor Might Order This Test
Doctors may request IgG testing to diagnose or monitor conditions like immunodeficiency, autoimmune diseases, infections, or to evaluate immune responses after vaccination.
Common Conditions Linked to IgG Levels
Low IgG levels may indicate weakened immunity, while high levels could suggest chronic infections, certain cancers, or overactive immune responses. This test isn’t used to diagnose specific conditions but supports broader immune health assessments.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate serum (the liquid part after clotting), which is then analyzed for IgG concentration. Results are typically reported as a qualitative (yes/no) or quantitative (specific concentration) measure.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
IgG levels are critical for diagnosing or managing conditions affecting immunity, such as primary immunodeficiency diseases, chronic infections (e.g., HIV, hepatitis), or autoimmune disorders (e.g., lupus). Elevated IgG can also be seen in some cancers or chronic inflammatory conditions. Always discuss results with your healthcare provider, as interpretation depends on your overall health and medical history.
Short name
IgG Level
Frequently asked questions
What does a low IgG level mean?
How often should I get this test?
Can diet or lifestyle 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