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Total Serum Immunoglobulin G (IgG) Level

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

This test measures the amount of Immunoglobulin G (IgG) in your serum. IgG is the most common type of antibody in your blood and helps protect your body from infections.

Quick summary

["IgG antibodies help fight infections and support long-term immunity."]

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

Key facts at a glance

LOINC
103574-0
Short code
Epid Allerg Dog IgE pl SerPl
Synonyms
Epid Allerg Dog IgE pl SerPl
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 IgG Measure?

IgG is a type of antibody produced by your immune system. It plays a key role in defending against bacteria and viruses. Your body makes IgG in response to infections and vaccines to provide long-term immunity. This test helps doctors assess your immune system’s ability to produce these protective proteins.

Why Might You Need This Test?

Doctors may order an IgG test to check for immune system issues, such as low antibody levels that could make you more susceptible to infections. It’s also used in diagnosing conditions like HIV, certain autoimmune diseases, or to monitor treatment responses in patients with immune-related disorders.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The blood is then processed to separate the serum (the liquid part after clotting). This serum is sent to a lab for testing. You may feel a slight pinch when the needle is inserted, but the process is quick and usually not painful.

What to Expect Before the Test

No special preparation is needed for this test. You can eat, drink, or take medications as usual. If you’re on blood-thinning medications, let your healthcare provider know before the test, as it may affect your blood clotting.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What causes low IgG levels?
Low IgG levels can be caused by conditions that affect your immune system, such as HIV/AIDS, certain autoimmune diseases, or genetic disorders like Common Variable Immunodeficiency (CVID). It may also occur in people who have had a bone marrow transplant or are undergoing chemotherapy.
What are common symptoms of low IgG?
Symptoms of low IgG levels may include frequent or severe infections, such as pneumonia, sinus infections, or ear infections. You might also experience slow wound healing, frequent colds, or recurrent skin infections. Some people with low IgG may not have obvious symptoms at first.
How is IgG tested and interpreted?
IgG levels are measured in the serum using immunoassay methods, such as nephelometry or turbidimetry. Results are compared to standard reference ranges to determine if your levels are within normal limits, low, or high. Your healthcare provider will discuss the results in the context of your overall health and medical history.
  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