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IgG Immunoglobulin (Serum) - Quantitative

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 diseases and supports long-term immunity."]

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

Key facts at a glance

LOINC
47327-2
Short code
Deprecated S pneum2 IgG Ser IA-mCnc
Synonyms
Deprecated S pneum2 IgG Ser IA-mCnc
Category
coagulation
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 This Test Might Be Ordered

Your healthcare provider may order this test to check for low or high IgG levels, which can occur in conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses or diagnose issues with antibody production.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood. The process takes about 5 minutes, and you may feel a brief pinch or slight discomfort. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

IgG levels vary depending on your health, age, and overall immune status. While reference ranges differ by lab, very low levels may suggest immune disorders, while very high levels could indicate chronic infections or certain diseases. Your provider will interpret results in the context of your medical history.

Common Conditions Linked to IgG Levels

Low IgG levels may be linked to primary immune deficiencies, HIV/AIDS, or conditions like celiac disease. High IgG levels can be seen in chronic infections, autoimmune diseases (e.g., lupus), or long-term inflammation. Your provider will discuss findings with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

What causes IgG levels to change?
IgG levels can change due to infections, immune system disorders, medications (e.g., steroids), or underlying health conditions like kidney disease or liver dysfunction. Age also plays a role—infants and young children have lower IgG levels than adults.
Can IgG levels be affected by diet?
Dietary factors like protein intake may indirectly affect IgG production, but they don’t directly alter test results. Focus on a balanced diet to support overall immune function, but discuss any concerns with your provider.
How often should IgG levels be checked?
Frequency depends on your health needs. If you have an immune disorder or chronic condition, your provider may recommend periodic monitoring. Otherwise, IgG tests are typically ordered only when symptoms or concerns arise.
  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