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Serum Immunoglobulin G (IgG) by Immunoassay

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody 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 marking pathogens for destruction."]

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

Key facts at a glance

LOINC
110030-4
Short code
A felis IgM Msmt Ser
Synonyms
A felis IgM Msmt Ser
Category
chemistry
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 in conditions like immune deficiencies, chronic infections, or certain autoimmune diseases. It may also be used to monitor treatment responses in patients with weakened immune systems.

What to Expect Before the Test

You can eat and drink normally before this test. No special preparation is needed unless instructed otherwise. Bring any medications you’re currently taking, as some may affect results.

How the Test Is Performed

A blood sample is drawn from a vein, usually in your arm, by a healthcare professional. The blood is processed to separate serum, which is then tested for IgG levels using an immunoassay method.

Possible Results and Their Meaning

Results may be below, within, or above normal reference ranges. Low IgG levels might suggest an immune deficiency, while high levels could indicate chronic infections, certain cancers, or other conditions. Your provider will discuss results with you in the context of your health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What does my IgG level tell me about my health?
IgG levels help assess your immune system’s ability to fight infections. Low levels may indicate a condition like Common Variable Immunodeficiency (CVID) or HIV, while high levels could signal chronic infections, autoimmune diseases, or certain cancers. Always discuss your results with your healthcare provider.
How often should I get this test?
Your provider will determine how often you need this test based on your medical history, symptoms, and treatment plan. Regular monitoring may be needed if you have an immune disorder or are undergoing treatment for one.
Can I eat or drink anything before this test?
You can eat and drink normally before this test unless your provider gives specific instructions. Avoid alcohol or certain medications that might affect blood test results.
  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