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Immunoassay for Immunoglobulin G (IgG) Substance Concentration in Serum

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG helps protect your body from infections.

Quick summary

["IgG levels help diagnose and monitor immune system conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
99764-3
Short code
IGNF CSF-mCnc
Synonyms
IGNF CSF-mCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It may also be used to check for conditions like immunodeficiency, autoimmune diseases, or to monitor treatment responses in certain conditions.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into a vein in your arm to draw blood. It usually takes a few minutes and may cause a slight pinch or bruising.

What the Results Mean

IgG levels can vary based on age, overall health, and medical conditions. High levels might indicate overactive immune responses or certain infections. Low levels may suggest immune deficiencies or chronic diseases. Your healthcare provider will interpret the results in the context of your overall health and medical history.

Common Conditions Affecting IgG Levels

IgG levels can be affected by conditions like HIV/AIDS, certain autoimmune diseases (e.g., lupus), chronic infections, or genetic disorders. It is also important to note that IgG levels can change over time due to aging, pregnancy, or certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

What are the normal ranges for IgG levels?
Normal IgG levels can vary and are determined by your healthcare provider based on your age, overall health, and specific medical context. They won’t be provided here as they can change with different testing methods and reference ranges used by labs.
How often should I get this test?
Your healthcare provider will determine how often you need this test based on your medical condition and treatment plan. Regular monitoring may be necessary for chronic conditions or ongoing treatments.
Can diet or lifestyle affect IgG levels?
Diet and lifestyle factors like nutrition, stress, and overall health can influence immune function, potentially affecting IgG levels indirectly. However, IgG levels are primarily measured in blood and are not directly impacted by diet alone unless there is an underlying health condition that requires dietary changes.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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