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Total 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 plays a key role in long-term immunity.

Quick summary

["IgG helps fight infections and supports long-term immunity by identifying and neutralizing harmful substances."]

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

Key facts at a glance

LOINC
24030-9
Short code
T canis IgM Ser Ql
Synonyms
T canis IgM Ser Ql
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 the most abundant antibody in your blood and is crucial for defending against bacteria and viruses. It circulates in your serum (liquid part of blood after clotting) and helps your immune system remember past infections to protect against future ones.

Why Might You Need This Test?

Doctors may order this test to check for immune system function, diagnose conditions like immunodeficiency, evaluate responses to vaccines, or monitor treatment for diseases affecting antibodies.

Common Reasons for Testing

Common reasons include assessing immune health, diagnosing conditions like HIV, lupus, or other autoimmune diseases, evaluating immune responses after vaccination, or monitoring immune-related treatments.

Sample Collection and Preparation

A blood sample is taken from a vein, usually in your arm. The blood is then processed to separate serum (the liquid part) for testing. This test does not require fasting.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What Are Normal IgG Levels?
Normal IgG levels vary by age and health status, so your doctor will compare your result to your specific baseline or reference ranges relevant to your situation.
How Long Does It Take to Get Results?
Results are typically available within 1–3 business days, depending on lab processing times and your healthcare provider’s workflow.
Can I Eat or Drink Before This Test?
No special preparation is needed. You can eat and drink normally before your blood draw.
  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