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Total Immunoglobulin G (IgG) in Serum

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 is the most common type of antibody in the bloodstream.

Quick summary

["IgG helps fight infections and supports long-term immunity by marking pathogens for destruction."]

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

Key facts at a glance

LOINC
24235-4
Short code
M pneumo IgG sp2 Ser-aCnc
Synonyms
M pneumo IgG sp2 Ser-aCnc
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 This Test Measure?

IgG is a key part of your immune system. It’s produced by your immune cells in response to infections, vaccines, or other triggers. High levels may indicate a strong immune response, while low levels could suggest immune deficiency or certain conditions.

Why Might You Need This Test?

Doctors may order an IgG test to check for immune system issues, monitor treatment for conditions like HIV, lupus, or other autoimmune diseases, or evaluate immune responses after vaccination.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or vein to draw blood. It usually takes a few minutes, and you may feel slight discomfort.

What to Expect After the Test

After the blood is drawn, a bandage will cover the site. You can return to your normal activities immediately. Rarely, you might experience bruising or mild soreness.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High IgG levels may be seen in chronic infections, some autoimmune diseases, or after vaccination. Low IgG levels can indicate immune system disorders, such as primary immunodeficiency, or conditions like HIV/AIDS that weaken immunity. Monitoring IgG helps guide treatment plans for long-term health.

Short name

IgG Level

Frequently asked questions

How long does it take to get results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time.
What does a low IgG level mean?
A low IgG level may suggest an immune deficiency or a condition that affects antibody production, such as HIV or certain autoimmune diseases. Your doctor will discuss further testing or treatment options based on your overall health.
Can I eat or drink before this test?
You can eat and drink normally before this test, as no special diet or fasting is required.
  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