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Serum Immunoglobulin G (IgG) Concentration

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

This test measures the amount of Immunoglobulin G (IgG), a key protein in your blood that helps fight infections and supports immune function.

Quick summary

["IgG helps protect your body from illness by identifying and neutralizing harmful substances."]

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

Key facts at a glance

LOINC
58967-1
Short code
GM3 IgM Ser IA-aCnc
Synonyms
GM3 IgM Ser IA-aCnc
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 Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. Antibodies are proteins that play a crucial role in your immune system by recognizing and fighting off bacteria, viruses, and other foreign invaders. IgG is particularly important for long-term immunity because it can stay in your body for years after an infection has passed.

Why Might You Need This Test?

Your doctor may order an IgG test to check for immune system health, diagnose conditions like immunodeficiency, evaluate responses to vaccines, or monitor chronic diseases such as lupus or rheumatoid arthritis.

How Is the Test Performed?

A small blood sample is drawn from a vein in your arm. The blood is then sent to a lab, where it is analyzed to measure IgG levels using a specialized immunoassay method.

What Does the Result Mean?

Results are typically reported as a concentration value (e.g., grams per liter). While reference ranges vary slightly by lab, lower than expected IgG levels may indicate weakened immunity, while higher levels could suggest conditions like multiple myeloma or chronic infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

Why was this test ordered?
Your doctor may have recommended this test to assess your immune response, diagnose a condition affecting antibodies, or monitor treatment progress for a disease linked to antibody function.
What are the typical reference ranges for IgG?
Reference ranges can vary by lab, but IgG levels are generally expressed in grams per liter (g/L). Your specific results will be compared to your lab’s standard values.
How often should I get this test?
Frequency depends on your health needs. Your doctor will determine how often to repeat this test based on your symptoms, diagnosis, or treatment plan.
  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