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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 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 providing protection against diseases."]

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

Key facts at a glance

LOINC
30505-2
Short code
Deprecated S pneum9 IgG sp1 Ser-mCnc
Synonyms
Deprecated S pneum9 IgG sp1 Ser-mCnc
Category
coagulation
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

Why This Test Might Be Ordered

Your healthcare provider may order this test to check for low or high levels of IgG, which can happen due to immune system issues, certain medical conditions, or after treatments like chemotherapy. It may also be used to monitor immune function in people with weakened immune systems, such as those with HIV/AIDS or after organ transplants.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for a few hours before the test if your blood is drawn early in the morning. Bring any medications you’re currently taking to your appointment.

What the Test Involves

A healthcare professional will draw blood from a vein, typically in your arm. The process is quick and usually causes only minor discomfort. The blood sample will be sent to a lab for analysis.

What the Results Mean

Results are compared to a reference range to determine if your IgG levels are within normal limits. Low IgG levels may indicate a weakened immune system, while very high levels might suggest certain autoimmune conditions or chronic infections. Your provider will discuss the results with you in the context of your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

What are the normal reference ranges for IgG?
Normal IgG levels vary slightly between labs, but they typically fall within the range of about 700 to 1,600 milligrams per deciliter (mg/dL) in adults. Your specific reference range will be provided by your healthcare provider based on your age, health, and other factors.
How often should I get this test?
The frequency of IgG testing depends on your medical condition and treatment plan. If you have a chronic illness or are undergoing immune-related treatments, your provider may recommend testing more often. Otherwise, this test is usually not part of routine check-ups unless symptoms suggest an issue with immunity.
Can lifestyle changes affect IgG levels?
Yes, certain lifestyle factors may influence IgG levels. A balanced diet rich in protein and vitamins, staying hydrated, and managing stress can support overall immune function. However, IgG levels are primarily influenced by your immune system’s response to infections and medical treatments, so lifestyle changes alone won’t significantly alter IgG levels unless they address underlying 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