Skip to content

Serum Immunoglobulin G (IgG) by Immunoassay

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 helps fight infections and supports immune function."]

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

Key facts at a glance

LOINC
66883-0
Short code
Skin IgG Titr Ser Monkey esoph
Synonyms
Skin IgG Titr Ser Monkey esoph
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Critical range
7.2 N/A – 7.6 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
monkey-esophagus-substrate
CPT
82977
SNOMED
3110003
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 type of antibody in your blood. It plays a key role in defending against bacteria and viruses. Your body produces IgG in response to infections or vaccines. Levels can vary depending on your immune health, age, and overall wellness.

Why Might You Need This Test?

Doctors may order an IgG test to check for immune system issues, such as low immunity (hypogammaglobulinemia), infections, or conditions like HIV, lupus, or certain autoimmune diseases. It’s also used in newborns to ensure they have enough antibodies from their mother.

When Might You Get This Test?

You might have this test if you have frequent infections, fatigue, or symptoms like frequent colds, pneumonia, or slow wound healing. It could also be part of a routine checkup for certain health conditions.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw a blood sample. This is usually quick and painless. If you’re nervous, let your doctor or nurse know.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels can help diagnose or monitor immune-related conditions. Low IgG levels may indicate a weakened immune system, while high levels could suggest chronic infections, inflammation, or certain immune disorders. Regular monitoring may be needed for ongoing health conditions.

Short name

IgG Level

Frequently asked questions

What Are Normal IgG Levels?
Normal IgG levels vary by age and can be checked with your doctor. They’re not always provided in test results unless needed for diagnosis.
How Long Does It Take to Get Results?
Results are typically available within a few days to a week, depending on your lab. Your doctor will discuss them with you.
Can I Eat or Drink Before the Test?
You can eat and drink normally before the test unless your doctor advises otherwise.
  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