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Serum Immunoglobulin G Substance Concentration (Total IgG)

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 supports your immune system’s defense against bacteria and viruses."]

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

Key facts at a glance

LOINC
110059-3
Short code
C immitis IgG Msmt Ser
Synonyms
C immitis IgG 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

What Does IgG Measure?

IgG is the primary antibody your immune system produces to fight off infections. It’s found in high levels in blood serum and plays a key role in long-term immunity. Your body produces IgG in response to pathogens like bacteria and viruses, helping to neutralize them and mark them for destruction by other immune cells.

Why Might You Need This Test?

Doctors may order an IgG test to check for immune system issues, such as low IgG levels that could indicate conditions like HIV, certain cancers, or immune deficiencies. It can also help diagnose or monitor autoimmune diseases, infections, or responses to vaccines.

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, which usually takes a few minutes. If you’re nervous, let your healthcare provider know so they can help make it more comfortable.

What to Expect After the Test

After the blood is drawn, you may feel a slight pinch or bruising at the site, but this usually goes away quickly. You can return to your normal activities right after. If you experience excessive bleeding or pain, contact your healthcare provider.

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 level be checked during pregnancy?
IgG levels can sometimes be checked during pregnancy to assess maternal immunity, especially if you’re at risk for infections or if you’ve had a recent illness. Low IgG might also be monitored in newborns to ensure they’re receiving adequate passive immunity from their mother.
What does it mean if my IgG level is lower than expected?
Lower-than-normal IgG levels may indicate an immune deficiency, chronic illness, or conditions like HIV/AIDS. It’s important to discuss your results with your doctor, as they may recommend further testing or treatments to address the underlying cause.
Can lifestyle changes affect my IgG levels?
While diet and lifestyle factors like stress or sleep can influence overall immune function, IgG levels are primarily determined by your body’s immune response. However, maintaining a balanced diet rich in vitamins and minerals may support immune health, but it won’t directly alter IgG levels.
  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