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Serum Immunoglobulin G (IgG) Level

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 harmful substances."]

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

Key facts at a glance

LOINC
51838-1
Short code
T palldm IgG Ser IA-aCnc
Synonyms
T palldm IgG Ser IA-aCnc
Category
chemistry
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

What Does This Test Measure?

IgG is one of the most common types of antibodies in your blood. It plays a key role in defending your body against bacteria and viruses. This test helps doctors assess your immune system’s ability to produce antibodies, which can be important for diagnosing or monitoring conditions like infections, autoimmune diseases, or immune deficiencies.

Why Might You Need This Test?

Your doctor may order an IgG test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or if you’re being treated for conditions like lupus, HIV, or certain cancers. It can also be used to monitor immune responses after vaccines or treatments.

How Is the Test Performed?

A small blood sample is taken from a vein in your arm. The blood is then sent to a lab where it’s analyzed to measure the IgG antibody levels. The test typically takes a few hours to complete, depending on lab processing times.

What Are Common Uses?

IgG testing is commonly used to diagnose or monitor conditions affecting the immune system, such as infections, autoimmune diseases, or immune-related cancers. It can also help evaluate immune function in people with chronic illnesses or those receiving immune-boosting treatments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What does an abnormal IgG level mean?
An abnormal IgG level may not have a single cause. Low IgG could mean your immune system isn’t producing enough antibodies, which might happen with certain genetic disorders, long-term illness, or treatments that weaken the immune system. High IgG levels might suggest chronic infections, autoimmune diseases, or other conditions that trigger an overactive immune response. Your doctor will consider your overall health and symptoms to interpret results.
How often should I get this test?
The frequency of IgG testing depends on your medical condition and why the test was ordered. If you have an ongoing health issue, your doctor may recommend testing at regular intervals to monitor changes in your immune function. For routine health checks, this test is usually not part of standard screening unless you have specific risk factors or symptoms.
Can lifestyle changes affect IgG levels?
While diet and lifestyle factors like stress, sleep, and exercise can influence overall immune health, they don’t directly change IgG levels. However, maintaining a balanced diet rich in vitamins and minerals, staying hydrated, and managing stress can support a healthy immune system, which may indirectly benefit antibody production.
  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