Skip to content

Mass concentration of immunoglobulin G (IgG) in serum or 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 helps protect your body from infections and diseases.

Quick summary

["IgG levels can help doctors assess immune function and identify conditions affecting antibodies."]

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

Key facts at a glance

LOINC
26814-4
Short code
M-IgG Ser-mCnc
Synonyms
M-IgG Ser-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 Does IgG Measure?

IgG is the most abundant antibody in your blood and plays a key role in long-term immunity. This test helps track how well your immune system is producing antibodies to fight infections or respond to vaccines.

Why Might You Need This Test?

Doctors may order an IgG test to diagnose or monitor conditions like immunodeficiency disorders, chronic infections, autoimmune diseases, or to check immune response after vaccination.

Sample Collection and Preparation

Blood is drawn from a vein, usually in your arm. The sample is sent to a lab where it is processed to separate serum or plasma for testing.

Test Results and Interpretation

Results are reported as a mass concentration (e.g., grams per liter). While reference ranges vary by lab, low levels may suggest weakened immunity, and high levels could indicate chronic infections or certain immune disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What causes IgG levels to be low?
Low IgG levels can result from conditions like HIV/AIDS, certain cancers, long-term use of steroids, or genetic immune disorders. It may also occur in people with malabsorption problems or those who have had severe infections.
What does it mean if my IgG levels are high?
Elevated IgG levels may signal chronic infections (e.g., hepatitis, tuberculosis), autoimmune diseases (e.g., rheumatoid arthritis), or certain cancers. In some cases, it can also be a normal response to repeated infections or vaccinations.
How often should I get this test?
Your doctor will determine how often you need this test based on your health condition, treatment plan, or symptoms. Regular monitoring may be needed if you have an immunodeficiency, chronic illness, or are receiving immune-modifying treatments.
  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