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Total Serum Immunoglobulin G (IgG) Level

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 antibodies play a key role in fighting infections and maintaining immune function."]

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

Key facts at a glance

LOINC
9459-9
Short code
Deprecated S pneum4 IgG Ser IA-aCnc
Synonyms
Deprecated S pneum4 IgG Ser IA-aCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 occur 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

No special preparation is usually needed. You may have a small needle inserted into your arm or vein to draw blood. If you’re nervous, let your healthcare provider know—they can help make it more comfortable.

What the Test Results Mean

Results are compared to a general range of normal values for IgG. While specific ranges can vary by lab, low IgG might suggest immune issues, while very high levels could indicate chronic infections or certain diseases. Your provider will discuss these results with you.

Common Conditions Affecting IgG Levels

Low IgG levels may be linked to conditions like Common Variable Immunodeficiency (CVID), HIV/AIDS, or long-term infections. High IgG levels can appear in chronic infections, certain cancers, or autoimmune disorders like rheumatoid arthritis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

Why might my IgG levels be checked during pregnancy?
IgG is passed from mother to fetus during pregnancy, but some conditions (like infections or immune disorders) may affect maternal levels. Your provider might check IgG to assess risks for the baby or monitor your health.
How often should I get this test if I have a known immune condition?
Frequency depends on your condition. Some patients with chronic immune issues get IgG tests every few months to track changes. Your doctor will tailor this based on your treatment plan and symptoms.
Can diet or supplements affect IgG levels?
Dietary changes alone rarely alter IgG levels significantly, but certain supplements (like vitamin D or omega-3s) may indirectly support immune function. Always discuss supplements with your provider before use.
  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