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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 type of antibody in your blood. IgG helps fight infections and is important for long-term immunity.

Quick summary

["IgG helps protect your body against infections and supports long-term immunity."]

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

Key facts at a glance

LOINC
14024-4
Short code
HTLV I+II p32 Ab Ser Ql IB
Synonyms
HTLV I+II p32 Ab Ser Ql IB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
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 harmful substances like bacteria and viruses. IgG provides long-term immunity by staying in your bloodstream for years, helping your body remember past infections to defend against future ones.

Why Might You Need This Test?

Your doctor may order an IgG test to check for low or high levels, which can happen in conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses in patients with conditions affecting antibody production.

When Is an IgG Test Performed?

This test is often done as part of a general blood workup, especially if you have symptoms like frequent infections, fatigue, or unexplained weight loss. It may also be ordered before receiving certain vaccines or during pregnancy to assess immune status.

What Does the Test Involve?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where it is analyzed to measure the amount of IgG antibodies present. The results help determine if your immune system is functioning normally or if there are issues that need further evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of IgG Levels

Short name

IgG Level

Frequently asked questions

What are the normal IgG levels?
IgG levels can vary based on age, overall health, and other medical conditions. While specific reference ranges are not provided here, your doctor will interpret the results in the context of your health history and symptoms. Low IgG levels may indicate a weakened immune system, while very high levels could be associated with certain autoimmune conditions or chronic infections.
How long does it take to get the results?
Test results are typically available within a few days to a week, depending on the lab and your healthcare provider’s workflow. Your doctor will contact you once the results are ready, either through a phone call or a follow-up appointment.
Can I eat or drink before the test?
You can usually eat and drink normally before this test unless your doctor specifies otherwise. For most blood tests, fasting is not required, but it’s always best to follow your healthcare provider’s instructions for the best accuracy of the results.
  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