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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 important for long-term immunity.

Quick summary

["IgG helps fight infections and supports long-term immunity by identifying and neutralizing pathogens."]

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

Key facts at a glance

LOINC
61316-6
Short code
Goldenrod IgE/IgE total %
Synonyms
Goldenrod 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 the most abundant antibody in your blood and plays a key role in defending against bacteria and viruses. This test checks the concentration of IgG in your serum, which can help assess your immune system’s ability to respond to infections and vaccines.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow healing wounds, or if you’re being treated for conditions like lupus, HIV, or certain autoimmune diseases. It can also be used to monitor immune function in people receiving treatments that suppress the immune system.

How Is the Test Done?

A blood sample is drawn from a vein in your arm. The blood is then processed to separate the serum, which is sent to a lab for analysis. The test measures the total amount of IgG antibodies present in your serum.

What Are Possible Results?

Results may be compared to a reference range provided by your healthcare provider, though exact values can vary by lab. Low IgG levels may indicate an immune deficiency, while very high levels could suggest certain immune disorders or chronic infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: IgG Levels and Immune Health

Short name

IgG Level

Frequently asked questions

What Are Common Causes of Abnormal Results?
Low IgG levels can be caused by conditions like primary immunodeficiency, chronic liver disease, malnutrition, or certain medications that weaken the immune system. High IgG levels may be linked to chronic infections, autoimmune diseases, or certain cancers.
How Often Should This Test Be Done?
The frequency depends on your health condition. If you have a known immune disorder or are undergoing treatment that affects immunity, your doctor may recommend regular monitoring. Otherwise, this test is often done only when symptoms or concerns arise.
Can Diet or Lifestyle Affect IgG Levels?
Dietary factors like protein intake and overall nutrition can indirectly support immune function, but IgG levels are primarily influenced by your body’s immune response and underlying health conditions. Stress, poor sleep, and chronic illness may also impact immune function.
  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