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Immunoassay for Immunoglobulin G (IgG) Substance Concentration in Serum/Plasma

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 levels help doctors check for immune system function and identify potential deficiencies or excesses."]

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

Key facts at a glance

LOINC
48419-6
Short code
IC IgG SerPl C1Q Bind-mCnc
Synonyms
IC IgG SerPl C1Q Bind-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
c-q-binding-assay
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 common antibody in your blood. It plays a key role in fighting off infections and helps your immune system remember past illnesses. This test helps determine how much IgG is present in your bloodstream.

Why Might You Need This Test?

Doctors may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It can also be used to monitor conditions like certain autoimmune diseases or after treatments that weaken the immune system, such as chemotherapy.

Sample Collection and Preparation

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

Common Reasons for Testing

IgG testing is often done to diagnose or monitor conditions affecting the immune system, such as infections, immune deficiencies, or autoimmune diseases. It can also be part of routine health checks for individuals at higher risk of immune-related issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level Test

Frequently asked questions

How is the test performed?
Blood is drawn from a vein, and the serum or plasma is analyzed using an immunoassay method to detect and quantify IgG antibodies.
What are the typical results or reference ranges?
There are no specific numeric reference ranges provided here since they can vary by lab and individual. Results are interpreted in relation to your clinical condition and overall health.
Can I eat or drink before this test?
No special preparation is needed, including no restrictions on food or drink before the 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