Skip to content

Immunoglobulin G (IgG) in Serum, Mass Concentration

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody in your blood serum. IgG is the most common antibody in the body and plays a key role in fighting infections and diseases.

Quick summary

["IgG helps your immune system defend against germs and helps your body remember past infections for faster protection in the future."]

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

Key facts at a glance

LOINC
47485-8
Short code
Deprecated S pneum17 IgG sp1 Ser-mCnc
Synonyms
Deprecated S pneum17 IgG sp1 Ser-mCnc
Category
coagulation
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 Is Immunoglobulin G (IgG)?

IgG, or Immunoglobulin G, is the most abundant antibody in your blood. It’s produced by your immune system to protect you from infections, including bacteria and viruses. IgG antibodies are also involved in fighting chronic infections and diseases like cancer. Your body produces IgG in response to exposure to pathogens (such as bacteria or viruses) or vaccines.

Why Might You Need This Test?

Your doctor may order an IgG test to check for low or high levels, which can indicate underlying health conditions. Low IgG levels might suggest weakened immunity, while high levels could be due to chronic infections, certain autoimmune diseases, or overproduction of antibodies.

When Is an IgG Test Performed?

This test is often done when you have symptoms of immune system issues, such as frequent infections, slow wound healing, or unexplained fatigue. It may also be part of a broader evaluation for conditions like lupus, HIV, or other immune disorders.

How Is the Test Done?

A small amount of blood is drawn from a vein in your arm. The blood is then sent to a lab, where it is analyzed to measure the concentration of IgG antibodies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What does an abnormal IgG level mean?
An abnormal IgG level may not have obvious symptoms, but it can indicate an underlying health issue. Low IgG levels might mean your immune system isn’t working as well as it should, while high levels could point to conditions like chronic infections or certain autoimmune diseases. Your doctor will interpret the results in the context of your overall health and symptoms.
How often should I get this test?
The frequency of IgG testing depends on your health condition and medical needs. If you have a known immune disorder, your doctor may recommend regular monitoring. Otherwise, this test is usually done only when symptoms or concerns suggest it’s needed.
Can lifestyle changes affect IgG levels?
While diet and lifestyle factors like stress or sleep can influence immune function, they don’t directly change IgG levels. However, maintaining good overall health—such as eating a balanced diet, staying hydrated, and managing stress—can help support your immune system’s ability to produce antibodies like IgG.
  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