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Immunoglobulin G (IgG) in Serum, Mass Concentration (Total)

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

This test measures the total amount of Immunoglobulin G (IgG), a type of antibody in your blood. IgG is the most common antibody and plays a key role in protecting you from infections.

Quick summary

["IgG helps fight bacteria and viruses, and is important for long-term immunity."]

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

Key facts at a glance

LOINC
25288-2
Short code
Deprecated S pneum19 IgG sp2 Ser-aCnc
Synonyms
Deprecated S pneum19 IgG sp2 Ser-aCnc
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 Does IgG Serve in the Body?

IgG antibodies are produced by your immune system in response to infections or vaccines. They help neutralize toxins and pathogens, providing long-lasting protection. IgG is also the primary antibody passed from mother to fetus during pregnancy to protect the newborn.

Why Might You Need This Test?

Your doctor may order an IgG test to check for immune system function, diagnose conditions like immunodeficiency, monitor treatment for diseases like lupus or multiple sclerosis, or evaluate immune responses to vaccines or infections.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate the serum, which is tested for IgG levels using a specialized immunoassay method.

What Are Common Results and Their Meanings?

Results are compared to standard ranges for healthy adults. Low IgG levels may indicate weakened immunity, while very high levels could suggest chronic infections, autoimmune conditions, or other health issues. Your doctor will interpret results in the context of your overall health and medical history.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: IgG Levels and Health Conditions

Short name

IgG Serum

Frequently asked questions

Why might my IgG levels be checked during pregnancy?
IgG levels are often monitored during pregnancy to ensure the fetus receives adequate antibodies from the mother. Low IgG in newborns can indicate potential immune deficiencies that may require further evaluation.
What conditions could cause IgG levels to be too low?
Low IgG levels can be associated with primary immunodeficiency diseases, chronic liver disease, malnutrition, or certain autoimmune conditions. Severe infections or prolonged illness may also deplete IgG reserves.
How do IgG levels change with age?
IgG levels naturally decline with age, which is why older adults may have lower baseline IgG. However, this decline can sometimes be accelerated by chronic illnesses or reduced immune function.
  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