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Serum Immunoglobulin G (IgG) Substance Concentration

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 immune function."]

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

Key facts at a glance

LOINC
63236-4
Short code
dsDNA IgM Ser Ql IF
Synonyms
dsDNA IgM Ser Ql IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It may also be used to monitor conditions like certain autoimmune diseases, chronic infections, or after receiving certain treatments like chemotherapy or organ transplants.

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. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

IgG levels can vary based on your health, age, and overall immune status. Low levels may suggest immune deficiency, while very high levels might indicate chronic infections, certain diseases, or overactive immune responses. Your provider will discuss results in the context of your medical history.

Common Conditions Monitored

IgG testing is often used to diagnose or track conditions like HIV/AIDS, certain autoimmune diseases (e.g., lupus), chronic infections (e.g., hepatitis), or immune deficiencies (e.g., common variable immunodeficiency).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

IgG is the most abundant antibody in your blood and plays a critical role in defending against bacterial and viral infections. Low IgG levels can indicate an impaired immune response, increasing susceptibility to infections. High levels may signal chronic inflammation, immune activation, or underlying diseases requiring further evaluation. Your provider will interpret results alongside your symptoms and medical history to guide next steps.

Short name

IgG Level

Frequently asked questions

What causes IgG levels to be low?
Low IgG levels can result from immune system disorders (e.g., primary immunodeficiency), chronic illnesses (e.g., HIV, lupus), certain medications, or conditions that affect nutrient absorption (e.g., celiac disease). Rarely, it may be congenital or linked to premature birth.
What causes IgG levels to be high?
High IgG levels can occur with chronic infections (e.g., hepatitis, tuberculosis), autoimmune diseases (e.g., rheumatoid arthritis), or certain cancers (e.g., multiple myeloma). Some medications or immune-stimulating therapies may also elevate IgG.
How often should IgG levels be checked?
Frequency depends on your health condition. If you have a chronic illness, immune disorder, or are undergoing treatment (e.g., chemotherapy), your provider may recommend periodic testing. For routine screening, IgG is usually not checked unless symptoms suggest a need.
  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