Skip to content

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 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 response to infections or treatments."]

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

Key facts at a glance

LOINC
78961-0
Short code
IgG/Alb clear Ur+SerPl-Rto
Synonyms
IgG/Alb clear Ur+SerPl-Rto
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 IgG Measure?

IgG is the most common type of antibody in your blood. It plays a key role in fighting off bacteria and viruses. Your body produces IgG in response to infections, vaccines, and other immune challenges. Levels can vary depending on your health, age, and immune status.

Why Might You Need This Test?

Doctors may order an IgG test to check for immune system issues, such as low immunity (immunodeficiency), infections, or responses to treatments like chemotherapy. It can also help diagnose conditions like lupus, HIV, or autoimmune diseases.

Sample Collection and Preparation

A blood sample is taken from a vein, usually in your arm. The blood is then separated into serum (liquid part after clotting) or plasma (liquid part after centrifugation). This sample is sent to a lab for testing.

What to Expect Before the Test

No special preparation is needed for this test. You can eat and drink normally, but let your doctor know if you’re on blood-thinning medications or have a history of bleeding disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels can provide important clues about your immune health. Low IgG levels may indicate a weakened immune system, while very high levels could suggest chronic infections, autoimmune diseases, or certain cancers. This test is often used alongside other tests to diagnose or monitor conditions like HIV, lupus, or immune deficiencies.

Short name

IgG Level

Frequently asked questions

When will I get my results?
Results are typically available within a few days to a week, depending on your lab. Your doctor will explain what the results mean in the context of your health.
What does a low or high IgG level mean?
Low IgG levels may mean your immune system isn’t working as well as it should, which can increase your risk of infections. High IgG levels can sometimes signal chronic infections, autoimmune diseases, or other health concerns. Your doctor will discuss these findings with you.
Can diet or supplements affect IgG levels?
Diet and supplements can indirectly support immune function, but they don’t directly change IgG levels. Focus on a balanced diet rich in vitamins, minerals, and proteins to help your immune system stay strong.
  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