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Serum/plasma mass concentration of immunoglobulin G (IgG) by immunoassay

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

This test measures the amount of Immunoglobulin G (IgG), the most common type of antibody in your blood. IgG helps protect your body from infections and diseases.

Quick summary

["IgG helps fight infections and supports immune function; levels may indicate immune health or response to treatments."]

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

Key facts at a glance

LOINC
58031-6
Short code
T palldm IgG CSF Ql
Synonyms
T palldm IgG CSF Ql
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What Is Immunoglobulin G (IgG)?

IgG is a type of antibody produced by your immune system to help defend against bacteria and viruses. It’s the most abundant antibody in your blood and plays a key role in long-term immunity. Your body produces IgG in response to infections, vaccines, and other immune challenges.

Why Might You Need This Test?

Your doctor may order an IgG test to assess your immune system’s ability to fight infections, evaluate conditions like immunodeficiency, monitor treatment responses (e.g., for autoimmune diseases or cancer), or check for signs of malnutrition or liver disease.

When Could You Expect Results?

Test results typically arrive within 1–3 business days, depending on your lab’s processing time. Your doctor will discuss the results with you during your follow-up visit.

What Does a Low or High IgG Level Mean?

Low IgG levels may suggest a weakened immune system, conditions like HIV/AIDS, or certain genetic disorders. High IgG levels could indicate chronic infections, autoimmune diseases, or overproduction of antibodies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels are crucial for diagnosing or monitoring conditions affecting immunity, such as primary immunodeficiency diseases, chronic infections, or immune-related disorders. Abnormal results may prompt further testing or treatment adjustments to address underlying causes.

Short name

IgG Level

Frequently asked questions

How is this test performed?
A blood sample is drawn from a vein in your arm. The blood is processed to separate serum or plasma, which is then tested for IgG using an immunoassay method to detect and measure antibody levels.
Is there any preparation needed?
No special preparation is required. You may eat or drink normally before your test, but avoid heavy exercise or stress that day.
Will the test hurt?
You may feel a slight pinch when the needle is inserted, but the procedure is quick and usually not painful. Most people experience minimal discomfort afterward.
  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