Skip to content

Immunoglobulin G (IgG) concentration in serum or plasma

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

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

Quick summary

["IgG levels help doctors assess your immune system’s strength and detect potential deficiencies or immune-related conditions."]

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

Key facts at a glance

LOINC
6781-9
Short code
IgG Ur IA-mCnc
Synonyms
IgG Ur IA-mCnc
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
CPT
82784
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Doctors may order an IgG test to check for immune system disorders, such as HIV, lupus, or other autoimmune diseases. It can also be used to evaluate immune function in newborns, people with chronic illnesses, or those receiving immune-suppressing treatments.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re concerned about needles, let your healthcare provider know in advance.

What the Results Mean

Results are compared to a general reference range, but your actual range may vary based on age, health, and other factors. Low IgG levels may indicate a weakened immune response, while very high levels could suggest certain immune disorders or infections.

Common Conditions Linked to IgG Levels

Low IgG levels can be linked to conditions like common variable immunodeficiency (CVID), HIV, or malnutrition. High levels may be seen in chronic infections, certain cancers, or autoimmune diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels play a critical role in immune defense, and abnormal results can signal underlying health concerns that need further medical evaluation.

Short name

IgG Level

Frequently asked questions

What causes IgG levels to be low?
Low IgG levels can result from immune system disorders, malnutrition, chronic illnesses, or certain medications that suppress the immune response. It’s important to discuss symptoms like frequent infections with your doctor.
How often should IgG levels be checked?
Your doctor will determine how often to check IgG levels based on your medical history, symptoms, and treatment plan. Regular monitoring may be needed if you have a known immune disorder or are undergoing treatment that affects immunity.
Can IgG levels change with age?
Yes, IgG levels can vary with age. Infants and young children may have lower IgG levels as their immune systems develop. In older adults, IgG levels may also fluctuate due to age-related immune changes or other health conditions.
  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