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Serum Immunoglobulin G (IgG) Level

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

This test measures the amount of Immunoglobulin G (IgG) in your blood, a key protein that helps fight infections and supports immune function.

Quick summary

["IgG helps protect your body against diseases and supports long-term immunity."]

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

Key facts at a glance

LOINC
107007-7
Short code
T. pallidum Ab.IgG 47 Ser Ql IB
Synonyms
T. pallidum Ab.IgG 47 Ser Ql IB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
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 This Test Is Done

Your healthcare provider may order this test to check for low or high levels of IgG, which can occur due to immune system issues, certain medical conditions, or after treatments like chemotherapy. It may also be used to monitor immune response in conditions like HIV, autoimmune diseases, or after organ transplants.

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. The process usually takes a few minutes, and you can resume normal activities afterward.

What the Results Mean

Results are compared to a general reference range, but exact values can vary by lab. Low IgG levels may suggest weakened immunity, while very high levels could indicate overactive immune responses or certain diseases. Your doctor will interpret results in the context of your overall health.

Common Reasons for Testing

IgG testing is often done to diagnose or monitor conditions like recurrent infections, immunodeficiency disorders, or to check immune recovery after illness or treatment.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What does a low IgG level mean?
A low IgG level may indicate a weakened immune system, which can make you more prone to infections. This could be due to conditions like HIV/AIDS, certain autoimmune diseases, or genetic disorders affecting immunity.
What causes high IgG levels?
High IgG levels can result from chronic infections, autoimmune diseases, or certain cancers. In some cases, it may also be a normal variation or due to long-term exposure to allergens or environmental factors.
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 an ongoing condition affecting immunity.
  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