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Immunoglobulin G (IgG) concentration, serum/plasma

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

This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps protect your body from infections and plays a role in long-term immunity.

Quick summary

["IgG antibodies help fight infections and support long-term immunity."]

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

Key facts at a glance

LOINC
76490-2
Short code
IgG Ur-sCnc
Synonyms
IgG Ur-sCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Does This Test Measure?

IgG is the primary antibody produced by your immune system in response to infections, vaccines, or other immune challenges. It circulates in your bloodstream and helps neutralize bacteria, viruses, and toxins. This test checks the concentration of IgG in your serum or plasma to assess your immune function.

Why Might You Need This Test?

Doctors may order an IgG test to evaluate your immune system’s ability to fight infections, diagnose conditions like immunodeficiency, monitor treatment responses in chronic diseases, or check for antibody deficiencies after certain medical treatments.

When Could You Expect Results?

Results are typically ready within 1–3 business days after your blood sample is drawn. Your healthcare provider will discuss the meaning of your results with you during your follow-up visit.

Common Reasons for Testing

Common reasons include recurrent infections, suspected immune disorders, pre- or post-transplant evaluations, or assessing immune response to vaccines. It may also be used in research or specialized diagnostic scenarios.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What Does a Low or High IgG Level Mean?
Low IgG levels may indicate an immune deficiency, where your body struggles to produce enough antibodies to fight infections. This can be congenital (present from birth) or acquired (due to illness, treatment, or aging). High IgG levels can sometimes signal chronic inflammation, autoimmune conditions, or exposure to repeated infections.
How Does This Test Relate to My Health?
IgG levels help doctors diagnose or monitor conditions like Common Variable Immunodeficiency (CVID), HIV/AIDS, or other immune-related disorders. They also guide treatment decisions, such as adjusting medications or planning vaccinations to boost immunity.
What If My Results Are Abnormal?
If your IgG level is outside the expected range, your healthcare provider will review your medical history and other test results to determine the cause. They may recommend further testing, lifestyle adjustments, or treatments to support your immune system.
  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