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Immunoassay for Immunoglobulin G (IgG) 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 is important for long-term immunity.

Quick summary

["IgG levels help assess immune function and detect deficiencies or excesses that may affect your health."]

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

Key facts at a glance

LOINC
87440-4
Short code
DENV1+2+3+4 IgA+IgG+IgM Spec IA-Imp
Synonyms
DENV1+2+3+4 IgA+IgG+IgM Spec IA-Imp
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 help your immune system recognize and fight off infections, such as bacteria and viruses. IgG is particularly important because it can cross the placenta to provide passive immunity to your baby during pregnancy.

Why Might You Need This Test?

Your doctor 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 autoimmune diseases, certain infections, or after receiving immune-boosting treatments.

How Is the Test Performed?

A blood sample is taken from a vein in your arm. The blood is then processed to separate the serum or plasma, which is sent to a lab for testing using an immunoassay method. This method detects the presence and concentration of IgG antibodies in your sample.

What Are Possible Results?

Results can vary depending on your health status. Low IgG levels may indicate an immune deficiency, while high levels could suggest certain infections, chronic diseases, or overactive immune responses. Your doctor will interpret the results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

What could my IgG test results mean for my health?
Low IgG levels may signal an immune system disorder, such as primary immunodeficiency, which can make you more susceptible to infections. High IgG levels might indicate chronic infections, autoimmune diseases, or other conditions that trigger an overproduction of antibodies. Your doctor will discuss these findings with you and may recommend further testing or treatments if needed.
How often should I get this test?
The frequency of IgG testing depends on your medical condition and symptoms. If you have a known immune deficiency or chronic illness, your doctor may recommend regular monitoring. Otherwise, this test is typically ordered only when symptoms or concerns suggest it is necessary.
Can lifestyle changes affect my IgG levels?
While diet and overall health can influence immune function, IgG levels are primarily determined by your body’s immune response. Certain medications, infections, or immune therapies may also impact IgG levels, so it’s best to discuss any changes with your healthcare provider.
  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