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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 type of antibody in your blood. IgG helps fight infections and is the most common antibody in the body.

Quick summary

["IgG levels help diagnose and monitor conditions affecting your immune system."]

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

Key facts at a glance

LOINC
25293-2
Short code
Deprecated S pneum12 IgG sp2 Ser-aCnc
Synonyms
Deprecated S pneum12 IgG sp2 Ser-aCnc
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 Might Be Ordered

Your healthcare provider may order this test if you have symptoms of an immune system disorder, such as frequent infections, low resistance to illness, or unexplained fatigue. It may also be used to check for conditions like immunodeficiency, autoimmune diseases, or to monitor treatment responses in certain cases.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, which usually takes a few minutes. If you’re on blood thinners or have a history of bleeding issues, let your provider know.

What the Results Mean

IgG levels can vary based on age, overall health, and medical conditions. High levels might suggest an overactive immune response or certain infections. Low levels could indicate a weakened immune system, which may need further evaluation.

Common Conditions Monitored

IgG levels are often checked in people with suspected immunodeficiency (like Common Variable Immunodeficiency), autoimmune diseases (such as lupus or rheumatoid arthritis), or those recovering from severe infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

How long does it take to get my IgG test results?
Results are typically available within 1 to 3 business days, depending on your lab. Follow-up with your healthcare provider to discuss the meaning of your results.
Can I eat or drink before this test?
You can eat and drink normally before this test unless instructed otherwise. No fasting is required.
What are typical IgG reference ranges?
Reference ranges vary by lab and individual factors. Your provider will interpret results in the context of your health and medical history.
  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