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Serum Immunoglobulin G (IgG) with qualitative or semi-quantitative measurement

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

This test measures the amount of Immunoglobulin G (IgG) in your blood. IgG is one of the key proteins in your immune system that helps fight infections.

Quick summary

["IgG helps protect your body against diseases and infections by identifying and neutralizing harmful substances."]

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

Key facts at a glance

LOINC
98221-5
Short code
T palldm IgG bands Ser IB
Synonyms
T palldm IgG bands Ser IB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
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

What IgG Does in Your Body

IgG, or Immunoglobulin G, is the most abundant antibody in your blood. It plays a critical role in long-term immunity by helping your body remember past infections and respond more effectively if you encounter the same pathogen again. IgG antibodies are produced in response to infections and vaccines, providing broad protection against a wide range of pathogens.

Why This Test Might Be Ordered

Your healthcare provider may order an IgG test to evaluate your immune system function. This could be done to diagnose or monitor conditions like immunodeficiency, autoimmune diseases, chronic infections, or to check immune response after vaccination.

When to Expect Results

Results for IgG tests are typically available within a few days to a week after your blood sample is drawn. Your doctor will discuss the results with you during your follow-up visit.

What to Expect During the Test

You will have a small needle inserted into your arm to draw blood. This process usually takes a few minutes. You may feel a slight pinch or discomfort, but it is generally well-tolerated. No special preparation is needed for this test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of IgG Levels

Short name

IgG Level

Frequently asked questions

How long does it take for IgG levels to change after a vaccination?
IgG levels can take several weeks to months to fully develop after vaccination. The exact timeline depends on the vaccine and your immune response. Your doctor may recommend follow-up testing if needed to monitor your immune response.
Can IgG levels be affected by diet?
Diet can indirectly influence immune function, but it does not directly affect IgG levels. A balanced diet rich in vitamins, minerals, and proteins supports overall immune health, which may indirectly support antibody production.
What conditions might cause low or high IgG levels?
Low IgG levels may be associated with conditions like primary immunodeficiency, chronic liver disease, or certain autoimmune diseases. High IgG levels can sometimes be seen in chronic infections, certain cancers, or as a reaction to vaccines or medications.
  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