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Immunoglobulin G (IgG) in Serum

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.

Quick summary

["IgG antibodies are crucial for long-term immunity and are often checked if you have recurring infections or immune system concerns."]

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

Key facts at a glance

LOINC
32849-2
Short code
Deprecated S pneum18 IgG Ser IA-mCnc
Synonyms
Deprecated S pneum18 IgG Ser IA-mCnc
Category
coagulation
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

Why Might This Test Be Ordered?

Your healthcare provider may order this test to assess your immune system function. This could be due to concerns about low IgG levels, which might indicate conditions like immunodeficiency, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses in patients with immune-related conditions.

What Does a Low or High IgG Level Mean?

Low IgG levels may suggest weakened immunity, making you more susceptible to infections. High levels could be seen in conditions like multiple myeloma or certain autoimmune diseases, though this is less common. Your results will be compared to standard reference ranges provided by your lab.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum, which is tested for IgG levels using an immunoassay method. This process helps determine the concentration of IgG antibodies in your blood.

What Are Common Reasons for Testing?

Common reasons include diagnosing or monitoring immune system disorders, evaluating recurrent infections, assessing newborns for congenital immune deficiencies, and monitoring patients undergoing treatments that may affect immunity.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What are the normal IgG levels in blood?
Normal IgG levels vary by lab and age but generally fall within a specific range provided by your healthcare provider or lab. IgG is the most abundant antibody in the blood and plays a key role in defending against bacteria and viruses. Abnormal levels may indicate underlying health issues that need further investigation.
How often should I get this test?
The frequency of testing depends on your medical condition and healthcare provider’s recommendations. Some patients may need this test annually or more often if they have chronic health issues or are undergoing specific treatments.
Can lifestyle changes affect IgG levels?
While diet and overall health can influence immune function, IgG levels are primarily determined by your body’s immune response. Lifestyle changes like maintaining a balanced diet, staying hydrated, and managing stress can support general immune health but may not directly alter IgG levels.
  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