Skip to content

Immunoassay for Human Immunoglobulin G (IgG) in Serum or Plasma

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody found 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 marking pathogens for destruction."]

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

Key facts at a glance

LOINC
69954-6
Short code
Hu2 IgG Ser Ql IA
Synonyms
Hu2 IgG Ser Ql IA
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 IgG Does in Your Body

IgG is the most abundant antibody in your blood and plays a key role in defending against bacteria and viruses. It helps your immune system remember past infections, providing long-term protection. Low levels may indicate immune deficiencies or certain medical conditions.

How the Test Works

This test uses an immunoassay method to detect and measure IgG in your blood. A small sample of your blood (serum or plasma) is taken and analyzed to determine your IgG concentration.

When You Might Need This Test

Doctors may order an IgG test to evaluate immune function, diagnose conditions like immunodeficiency, check for antibody responses after vaccination, or monitor immune-related diseases.

Possible Results and Next Steps

Results are typically reported as a concentration value (e.g., grams per liter). If your IgG level is lower than expected, your doctor may recommend further testing or treatments to address potential immune issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low IgG levels may suggest an immune system disorder, such as common variable immunodeficiency (CVID), or could indicate chronic illnesses like lupus or HIV. High levels may be seen in chronic infections, autoimmune diseases, or certain cancers. IgG testing helps guide treatment plans and monitor immune health.

Short name

IgG Level

Frequently asked questions

Why might my IgG test be ordered?
Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or if you’ve had a recent vaccination and don’t seem to have developed immunity.
What does it mean if my IgG level is low?
A low IgG level could mean your immune system isn’t producing enough antibodies to fight infections effectively. This may require further evaluation by a specialist to determine the cause and appropriate treatment.
How often should I get this test?
The frequency depends on your health condition and doctor’s recommendations. Some people with chronic immune issues may need regular monitoring, while others may only need it once or twice a year.
  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