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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), a type of antibody in your blood. IgG helps protect your body from infections and diseases.

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
57678-5
Short code
M pneumo IgG sp2 Ser Ql IA
Synonyms
M pneumo IgG sp2 Ser Ql IA
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
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 the most abundant antibody in your blood. It helps fight off bacteria and viruses by marking them for destruction by other immune cells. Levels can vary depending on your immune response, overall health, and exposure to infections.

Why Might You Need This Test?

Your doctor may order this test to check for immune system function, diagnose conditions like immunodeficiency, evaluate treatment responses for autoimmune diseases, or assess immune status in newborns or individuals with chronic illnesses.

How Is the Sample Collected?

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch when the needle is inserted, but it typically only takes a few minutes. The blood is then sent to a lab for testing.

What Are Common Reasons for Testing?

Common reasons include monitoring immune health, diagnosing conditions like HIV, lupus, or other autoimmune diseases, evaluating newborns for congenital immune deficiencies, or checking for infections where IgG levels might be abnormal.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

Why do I need this test?
Your doctor may recommend this test to better understand your immune system’s ability to fight infections, to diagnose or monitor conditions affecting antibodies, or to guide treatment plans for chronic illnesses.
What do my IgG levels mean?
IgG levels can be lower than normal in people with weakened immune systems (e.g., due to certain genetic conditions, HIV/AIDS, or long-term illness), or higher than normal in some autoimmune diseases or chronic infections. Your doctor will interpret results in the context of your overall health.
How long will it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your doctor will discuss the findings with you during your follow-up visit.
  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