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Serum Immunoglobulin G (IgG) Level

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

This test measures the amount of Immunoglobulin G (IgG) in your blood. IgG is the most common type of antibody in your body and helps protect against infections.

Quick summary

["IgG antibodies play a key role in long-term immunity."]

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

Key facts at a glance

LOINC
106936-8
Short code
T palldm IgG+IgM SerPlBld Ql IA.rapid
Synonyms
T palldm IgG+IgM SerPlBld Ql IA.rapid
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia-rapid
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

Why This Test Is Done

Doctors may order an IgG test to check for immune system function, diagnose conditions like immunodeficiency, or monitor treatment for diseases such as HIV, lupus, or certain cancers. It can also help evaluate immune responses after vaccination.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood, which usually takes just a few minutes. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Results can vary based on age, health, and other factors. Low IgG levels may indicate weakened immunity, while very high levels could suggest chronic infections, autoimmune diseases, or certain cancers. Your doctor will interpret results in the context of your overall health.

Common Conditions Linked to IgG Levels

Abnormally low IgG levels may be linked to conditions like Common Variable Immunodeficiency (CVID), HIV/AIDS, or severe infections. High IgG levels can be seen in chronic infections, autoimmune diseases (e.g., rheumatoid arthritis), or long-term exposure to certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: IgG levels are critical for diagnosing and managing immune-related disorders. Low IgG is often associated with recurrent infections, while elevated IgG may indicate chronic inflammation or immune system overactivity. Monitoring IgG helps guide treatment for conditions like immunodeficiency, autoimmune diseases, or chronic infections.

Short name

IgG Level

Frequently asked questions

What causes IgG levels to be low?
Low IgG levels can result from immune system disorders (such as CVID), certain infections (like HIV), or conditions that affect antibody production (e.g., liver disease or malnutrition). It may also occur in newborns due to maternal antibodies waning.
What causes IgG levels to be high?
High IgG levels are often seen in chronic infections, autoimmune diseases (like lupus or rheumatoid arthritis), or as a reaction to certain vaccines or medications. In some cases, it may also be a normal variation in response to repeated exposures to antigens.
Can IgG levels change over time?
Yes, IgG levels can fluctuate due to infections, vaccinations, aging, or underlying health conditions. Regular monitoring may be needed if you have a condition that affects immunity, such as HIV or autoimmune disease.
  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