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Immunoglobulin G (IgG) mass concentration in serum/plasma

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

This test measures the amount of Immunoglobulin G (IgG), a key antibody protein in your blood that helps fight infections and supports immune function.

Quick summary

["IgG helps protect your body from illness by identifying and neutralizing harmful substances."]

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

Key facts at a glance

LOINC
27096-7
Short code
Deprecated S pneum3 IgG Ser-mCnc
Synonyms
Deprecated S pneum3 IgG Ser-mCnc
Category
coagulation
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

Why This Test Is Done

Your doctor may order an IgG test to check for low or high levels, which can indicate conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used during pregnancy to monitor fetal health or in research settings to assess immune responses.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re pregnant or have a history of bleeding disorders, let your healthcare provider know before the test.

How the Test Results Are Interpreted

Results are compared to standard reference ranges, though exact values can vary by lab. Low IgG levels may suggest immune system weakness, while very high levels could indicate chronic infections or certain cancers.

Common Conditions Affecting IgG Levels

Conditions like HIV/AIDS, certain cancers (e.g., multiple myeloma), or long-term infections (e.g., hepatitis) can alter IgG levels. Autoimmune diseases (e.g., lupus) may also lead to abnormal IgG production.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What does a low IgG level mean?
A low IgG level may indicate a weakened immune system, putting you at higher risk for infections. It could be due to conditions like primary immunodeficiency, chronic liver disease, or certain medications that suppress immune function.
What does a high IgG level mean?
High IgG levels can signal chronic infections, autoimmune disorders, or certain cancers. In some cases, it may also reflect a normal immune response to repeated or severe infections.
How often should I get this test?
Your doctor will determine the frequency based on your health status, symptoms, or treatment plan. Regular monitoring may be needed if you have an ongoing condition affecting IgG levels.
  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