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Immunoglobulin G (IgG) mass concentration in serum/plasma

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 important for fighting infections and providing long-term immunity.

Quick summary

["IgG helps protect your body from diseases by recognizing and neutralizing harmful substances."]

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

Key facts at a glance

LOINC
49099-5
Short code
Codfish IgG-mCnc
Synonyms
Codfish IgG-mCnc
Category
chemistry
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 Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. It plays a key role in defending against bacteria and viruses, helping your immune system remember past infections to fight them more effectively in the future. Levels of IgG can vary depending on your health, immune status, and certain medical conditions.

Why Might You Need This Test?

Your healthcare provider may order an IgG test to check for immune system issues, such as low immunity (hypogammaglobulinemia), infections, or conditions like HIV, lupus, or certain cancers. It can also be used to monitor treatment responses in people with immune-related disorders.

When Is This Test Done?

This test is typically performed by drawing blood from a vein in your arm. The blood sample is sent to a lab where it is analyzed to determine the IgG concentration. Results help assess immune function and guide medical decisions.

What Do the Results Mean?

Results are usually reported as a mass concentration (e.g., grams per liter). Low IgG levels may indicate weakened immunity, while high levels might suggest certain immune disorders or chronic infections. Your doctor will interpret the results in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

Could low IgG levels affect my health?
Yes, low IgG levels can weaken your immune system, making you more susceptible to infections like pneumonia, sinus infections, or urinary tract infections. It may also indicate conditions like common variable immunodeficiency (CVID) or other immune disorders that require medical attention.
Are there any risks or side effects from this blood test?
The most common side effect is mild bruising, swelling, or discomfort at the injection site. Rarely, there may be a slight reaction to the needle. Most people experience no serious side effects from this simple blood draw.
How often should I get this test?
Your doctor will determine the frequency based on your medical history, symptoms, and treatment needs. Some people may need this test annually or more often if they have an immune-related condition or are receiving treatment for one.
  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