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IgG Immunoglobulin (Serum) – Quantitative

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 long-term immunity."]

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

Key facts at a glance

LOINC
25292-4
Short code
Deprecated S pneum12 IgG sp1 Ser-aCnc
Synonyms
Deprecated S pneum12 IgG sp1 Ser-aCnc
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

What Is IgG Used For?

IgG levels are often checked to evaluate immune function, diagnose conditions like immunodeficiency, or monitor treatment responses in people with chronic illnesses. It can also help identify if you have enough antibodies to protect against certain infections.

Why Might You Need This Test?

Your doctor may order an IgG test if you have symptoms of a weakened immune system (such as frequent infections), if you’re being treated for an autoimmune disease, or if you’re planning to receive certain vaccines that require prior immunity.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw a blood sample. The process is quick and usually painless.

What to Expect During the Test

After your blood is drawn, you’ll likely rest for a few minutes. Most people experience only minor discomfort or bruising at the injection site.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

IgG Level

Frequently asked questions

Low IgG levels may indicate an immune deficiency, where your body struggles to fight infections effectively. High IgG levels could suggest chronic inflammation, autoimmune conditions, or exposure to certain infections.
IgG tests help doctors diagnose or monitor conditions like HIV, hepatitis, or other chronic illnesses. They can also guide decisions about vaccine safety or timing for people with immune disorders.
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. Your doctor will discuss the findings with you during your follow-up visit.
What does a high IgG level mean?
High IgG levels might indicate chronic inflammation, an autoimmune condition (like rheumatoid arthritis), or exposure to repeated infections. Your doctor will review your symptoms and other test results to understand the cause and recommend appropriate care.
  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