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Total Immunoglobulin G (IgG) in Serum

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

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

Quick summary

["IgG antibodies play a key role in long-term immunity and are often checked if you have symptoms of immune system issues or recurrent infections."]

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

Key facts at a glance

LOINC
56958-2
Short code
M pneumo IgG sp1 Ser IA-aCnc
Synonyms
M pneumo IgG sp1 Ser IA-aCnc
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

Why Is This Test Done?

Your healthcare provider may order this test to evaluate your immune system function. Possible reasons include diagnosing or monitoring conditions like immunodeficiency, autoimmune diseases, or infections. It may also be used before certain vaccines to check baseline antibody levels.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re nervous, let your provider know—they can help make it more comfortable.

What Happens During the Test?

A healthcare professional will collect a blood sample from a vein in your arm. The sample is then sent to a lab for analysis. The results are usually available within a few days.

What the Results Mean

Results are compared to standard ranges for healthy adults. Low IgG levels may indicate weakened immunity, while very high levels could suggest certain immune disorders or chronic infections. Your provider will discuss these findings with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels help identify or monitor conditions affecting the immune system, such as primary immunodeficiency diseases (e.g., common variable immunodeficiency), autoimmune disorders (e.g., lupus), or chronic infections (e.g., HIV). It can also assess response to treatments like immunoglobulin therapy or vaccines.

Short name

IgG Level

Frequently asked questions

What causes low IgG levels?
Low IgG levels can result from conditions like severe immune deficiencies, chronic liver disease, malnutrition, or certain medications. It may also appear in people with long-term infections or those who have had a bone marrow transplant.
What causes high IgG levels?
High IgG levels are often seen in chronic infections, autoimmune diseases (e.g., rheumatoid arthritis), or certain cancers. Rarely, they can occur due to overactive immune responses or long-term exposure to certain substances.
How often should I get this test?
Your provider will determine the frequency based on your health status, symptoms, or treatment plan. Some people may need this test yearly, while others may only need it occasionally or as needed for monitoring.
  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