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Immunoglobulin G (IgG) concentration in serum/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 levels help assess immune function and detect deficiencies or excesses that may affect your health."]

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

Key facts at a glance

LOINC
96491-6
Short code
NIF IgG Titr CSF IF
Synonyms
NIF IgG Titr CSF IF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82977
SNOMED
3110003
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What Does IgG Measure?

IgG is the most abundant antibody in your blood, playing a key role in fighting infections and providing immunity. This test evaluates its concentration, which can vary depending on your immune status, health conditions, or medical treatments.

Why Might You Need This Test?

Your doctor may order an IgG test to check for immune system issues, such as low levels that could indicate conditions like HIV, certain cancers, or autoimmune diseases. It may also be used to monitor treatment responses or diagnose infections.

Common Reasons for Testing

Common reasons include evaluating immune function before vaccines, diagnosing or monitoring conditions like chronic infections, or assessing immune responses to treatments like chemotherapy.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to measure IgG levels using an immunoassay method, which detects the antibody concentration in your serum or plasma.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: csf

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What Are Normal IgG Levels?
Normal IgG levels can vary, but low levels may suggest immune deficiencies, while very high levels could indicate chronic infections, certain cancers, or overactive immune responses. Your doctor will interpret results in the context of your health history.
How Long Does It Take to Get Results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Follow-up with your healthcare provider to discuss any findings.
Can Diet or Medications Affect IgG Levels?
Dietary factors or certain medications may indirectly influence immune function, but IgG levels are primarily measured in blood and not directly affected by short-term diet changes. Always discuss medications with your doctor.
  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