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Immunoglobulin G (IgG) in Serum

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.

Quick summary

["IgG antibodies play a key role in long-term immunity."]

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

Key facts at a glance

LOINC
110728-3
Short code
L mexicana IgM Msmt Ser
Synonyms
L mexicana 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
86038
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 Is This Test Done?

Your healthcare provider may order this test to check for low or high levels of IgG, which can indicate conditions like immune deficiencies, infections, or certain autoimmune diseases. It may also be used to monitor treatment responses in people with chronic illnesses.

What Does the Test Involve?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab where it is processed to measure IgG levels using an immunoassay method.

What Do Results Mean?

Results are compared to standard ranges to determine if your IgG levels are within normal limits, lower than expected, or higher than expected. Interpretation depends on your overall health and medical history.

What Are Possible Causes of Abnormal Results?

Low IgG levels might suggest an immune system disorder, such as common variable hypogammaglobulinemia, or conditions that affect absorption in the gut. High IgG levels could be linked to chronic infections, certain cancers, or autoimmune diseases.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG levels can help diagnose or monitor conditions affecting immunity, infections, or autoimmune responses. For example, low IgG may indicate a need for immune support, while high IgG might prompt further investigation into underlying causes like chronic inflammation or malignancy.

Short name

IgG Level

Frequently asked questions

Why might my IgG test be done regularly if I have a chronic condition like lupus or HIV?
Regular IgG testing may be recommended to monitor how your immune system is responding to treatment, track changes in your condition, or ensure your immune support remains effective over time.
What should I do if my IgG test results are abnormal?
If your results are outside the normal range, your healthcare provider will discuss next steps, which may include additional tests, changes in treatment, or further evaluation of your health condition.
Can diet or supplements affect IgG levels?
Dietary changes or supplements may indirectly influence immune function, but they do not directly alter IgG levels. Always follow your healthcare provider’s advice regarding dietary or supplement 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