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Immunoglobulin G (IgG) in Serum

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody found in your blood. IgG helps protect your body from infections and diseases by fighting bacteria and viruses.

Quick summary

["IgG levels help assess your immune system’s strength and response to infections or vaccines."]

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

Key facts at a glance

LOINC
47339-7
Short code
Deprecated S pneum34 IgG Ser IA-mCnc
Synonyms
Deprecated S pneum34 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 Might This Test Be Done?

Your healthcare provider may order an IgG test to check for low or high levels, which can indicate conditions like immune deficiencies, infections, or responses to treatments such as vaccines or medications. It may also be used to monitor chronic illnesses or evaluate immune function in people with certain diseases or after organ transplants.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into a vein in your arm to collect a blood sample. The process usually takes a few minutes and is generally painless.

What to Expect During the Test

The blood sample will be sent to a lab for analysis. Results are typically available within a few days, depending on lab processing times.

Possible Results and Interpretation

Results can vary widely based on individual health, age, and other factors. Low IgG levels may suggest an immune disorder, while very high levels could indicate chronic infections or certain autoimmune conditions. Your healthcare provider will discuss the results with you in detail and determine if further testing or treatment is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

What does my IgG level mean for my health?
IgG levels are critical for diagnosing and managing conditions affecting the immune system. Low IgG levels can point to conditions like Common Variable Immunodeficiency (CVID) or other primary immune deficiencies, which may require lifelong monitoring or treatment. High IgG levels might suggest chronic infections, such as hepatitis or HIV, or could be a side effect of certain medications. Always discuss your results with your healthcare provider to understand their implications for your specific situation.
How often should I get this test?
The frequency of IgG testing depends on your medical history, symptoms, and treatment plan. If you have a known immune disorder or are undergoing treatment for an infection or disease, your provider may recommend regular monitoring. If you are healthy, this test may not be routinely recommended unless you have specific risk factors or concerns.
Can lifestyle changes affect my IgG levels?
While diet and lifestyle factors like stress and sleep can influence overall immune function, IgG levels are primarily determined by your body’s immune response. Certain foods rich in vitamins (like vitamin D and zinc) may support immune health, but they do not directly alter IgG concentrations. Always follow your healthcare provider’s advice regarding lifestyle adjustments related to your test results.
  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