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Serum Immunoglobulin G (IgG) Substance Concentration

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody found in your blood. IgG helps protect your body from infections and diseases.

Quick summary

["IgG helps fight infections and supports immune function."]

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

Key facts at a glance

LOINC
110144-3
Short code
Stria Mus IgG Msmt Ser
Synonyms
Stria Mus IgG Msmt Ser
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 Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. It plays a key role in defending your body against bacteria and viruses. Your immune system produces IgG in response to infections or vaccines, helping to remember past illnesses and protect against future ones.

Why Might You Need This Test?

Doctors may order an IgG test to check for low or high levels, which can happen due to immune system issues, certain medical conditions, or after treatments like chemotherapy. It may also be used to monitor immune responses to vaccines or infections.

Common Reasons for Testing

Common reasons include diagnosing immune deficiencies, evaluating immune responses, checking for autoimmune diseases, or assessing conditions like HIV, hepatitis, or certain cancers.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if your blood is drawn early in the morning. Wear comfortable clothing and plan to stay near the testing site for a short time.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

How is this test done?
A healthcare provider will take a small blood sample from a vein in your arm using a needle. You may feel a slight pinch, but it usually doesn’t cause discomfort. The sample is then sent to a lab for analysis.
Will the test hurt?
Most people experience only mild discomfort or a brief pinch during the blood draw. Some may feel a slight bruise or swelling at the site, but this usually goes away quickly.
How long will I have to wait for results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss the findings with you during your follow-up visit.
  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