Skip to content

Total Immunoglobulin G (IgG) Concentration

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 diseases.

Quick summary

["IgG levels help assess immune function and identify potential immune deficiencies."]

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

Key facts at a glance

LOINC
64966-5
Short code
Wheat (rTri a) 14 IgE Qn
Synonyms
Wheat (rTri a) 14 IgE Qn
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 Is Immunoglobulin G (IgG)?

IgG is the most common type of antibody in your blood. It plays a key role in fighting off infections by helping your immune system recognize and neutralize harmful substances, such as bacteria and viruses. IgG is also important for long-term immunity, as it can stay in your body for years after an infection has passed.

Why Might You Need This Test?

Doctors may order an IgG 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 to monitor conditions like HIV, certain autoimmune diseases, or after receiving immune-boosting treatments like chemotherapy.

Sample Collection and Preparation

For this test, a small amount of blood is drawn from a vein in your arm. The blood sample is then sent to a lab for analysis. IgG levels are typically measured using an immunoassay method, which detects the presence and concentration of IgG antibodies in your blood.

What to Expect Before the Test

There are no special preparations needed for this test. However, if you are on certain medications that affect your immune system, your doctor may advise you to stop them temporarily or adjust your dosage before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of IgG Levels

Short name

IgG Level

Frequently asked questions

What does a low IgG level mean?
Low IgG levels may indicate an immune deficiency, which can make you more susceptible to infections. Conditions that can cause low IgG include certain genetic disorders, chronic illnesses, or treatments that suppress the immune system. Your doctor may recommend further testing or treatments to support your immune function.
What does a high IgG level mean?
High IgG levels can sometimes be a sign of an overactive immune response, such as in chronic infections, autoimmune diseases, or certain types of cancer. They may also be found in people with long-term inflammatory conditions. Your doctor will discuss the results with you and may recommend additional tests to understand the cause.
How often should I get this test?
The frequency of IgG testing depends on your health condition and medical history. If you have a known immune disorder, your doctor may recommend regular monitoring. Otherwise, this test is usually performed only when symptoms or concerns suggest it is needed.
  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