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Total 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 in your blood. IgG helps protect your body from infections and is one of the most abundant antibodies in the bloodstream.

Quick summary

["IgG helps fight infections and supports immune function; low levels may indicate immune deficiency or chronic illness."]

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

Key facts at a glance

LOINC
50369-8
Short code
White Oak IgE/IgE total %
Synonyms
White Oak IgE/IgE total %
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Does This Test Measure?

IgG is a key component of your immune system. It’s produced by your immune cells in response to infections, vaccines, and other immune challenges. Measuring IgG helps doctors assess your immune response and identify potential issues with antibody production.

Why Might You Need This Test?

A doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It can also be used before vaccines to check if your body will respond effectively.

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 a blood sample. The test is quick and usually done in a doctor’s office or lab.

What the Results Mean

Results can vary based on your 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 doctor will discuss the results with you.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

How often should I get this test?
This test is typically ordered as needed, depending on your symptoms or medical condition. If you have a chronic illness or immune disorder, your doctor may recommend periodic testing to monitor your IgG levels over time.
What causes low IgG levels?
Low IgG levels can result from conditions like primary immunodeficiency, chronic liver disease, malnutrition, or certain autoimmune disorders. In infants, low IgG may indicate a genetic immune deficiency.
Can diet affect IgG levels?
Diet can influence overall immune function, but IgG levels are primarily determined by your body’s immune response. Eating a balanced diet rich in vitamins and minerals supports immune health, but it does not directly alter 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