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Serum Immunoglobulin G (IgG) Level

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 by fighting bacteria and viruses.

Quick summary

["IgG antibodies play a key role in long-term immunity and are often checked if you have recurring infections or immune system concerns."]

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

Key facts at a glance

LOINC
17649-5
Short code
S pneum IgG 1:2 Ser IA-Rto
Synonyms
S pneum IgG 1:2 Ser IA-Rto
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 recommend this test if you have symptoms like frequent infections, low energy, or if they suspect an immune disorder. It can also be part of monitoring for conditions like HIV, lupus, or certain autoimmune diseases.

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 blood, which usually takes a few minutes. You can eat and drink normally before the test.

What the Results Mean

IgG levels can vary based on your health, age, and overall immune status. High levels might indicate a strong immune response, while very low levels could suggest immune deficiency or certain diseases. Your results will be discussed with your healthcare provider.

Common Reasons for Testing

IgG testing is often done to diagnose or monitor conditions like chronic infections, immune system disorders, or to check for antibodies in cases of exposure to diseases like HIV or hepatitis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What does an abnormal IgG level mean?
An abnormal IgG level can signal potential health issues. Low levels may point to an immune deficiency or chronic illness, while very high levels could indicate an overactive immune response or certain diseases. Your provider will review these results with you to determine the next steps.
How often should I get this test?
The frequency of this test depends on your medical condition and healthcare provider’s recommendations. Some people may need it yearly or more often if they have ongoing health concerns like frequent infections or an immune disorder.
Can diet or supplements affect IgG levels?
Diet and supplements can indirectly influence immune function, but they do not directly affect IgG levels. Focus on a balanced diet rich in vitamins and minerals to support overall immune health, but discuss any supplements with your provider first.
  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