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Total Immunoglobulin G (IgG) Level

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG is the most common antibody and plays a key role in fighting infections.

Quick summary

["IgG helps your immune system defend against bacteria and viruses."]

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

Key facts at a glance

LOINC
42923-3
Short code
Firebush IgE/IgE total %
Synonyms
Firebush IgE/IgE total %
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Does This Test Measure?

IgG is a protein produced by your immune system to help fight infections. It’s the most abundant antibody in your blood and is essential for long-term immunity. This test helps doctors assess your immune response, especially after vaccination or infection.

Why Might You Need This Test?

Your doctor may order this test to evaluate your immune system, check for conditions like immunodeficiency, monitor immune responses after treatments (such as chemotherapy), or assess immune function in chronic illnesses.

How Is the Test Performed?

A small blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for analysis using an immunoassay method to measure IgG levels.

What Are Common Uses?

IgG testing is often used in diagnosing or monitoring conditions like HIV, autoimmune diseases, or congenital immunodeficiency disorders. It can also help determine if vaccines are working properly.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels can be low in people with weakened immune systems, chronic illnesses, or certain genetic disorders. High levels may indicate chronic infections, certain cancers, or autoimmune reactions. Always discuss results with your healthcare provider.

Short name

IgG Total

Frequently asked questions

What does a low IgG level mean?
A low IgG level may suggest an immune system that isn’t working as well as it should, which could increase your risk of infections. Your doctor may recommend further testing or treatments to support your immune function.
How often should I get this test?
The frequency depends on your health condition. Some people need this test yearly, while others may need it more often if they have ongoing medical concerns or treatments affecting their immune system.
Can diet or supplements affect IgG levels?
Diet and supplements can indirectly support immune function, but they don’t directly change IgG levels. Focus on a balanced diet rich in vitamins and minerals to help your immune system stay strong.
  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