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Immunoglobulin G (IgG) in Serum or Plasma

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 long-term immunity and disease defense."]

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

Key facts at a glance

LOINC
96479-1
Short code
IgLON5 IgG CSF Ql IF
Synonyms
IgLON5 IgG CSF Ql IF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82784
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may order an IgG test to check for low or high levels, which can happen due to immune system issues, infections, or certain medical conditions. It may also be used to monitor treatment responses, such as in autoimmune diseases or after receiving certain vaccines.

What to Expect Before the Test

No special preparation is usually needed. You may have blood drawn from a vein in your arm, or a small sample of blood may be collected for testing. If you’re taking blood from your own arm at home, follow your healthcare provider’s instructions carefully.

What the Test Results Mean

Results are typically reported as a concentration of IgG in the blood. While reference ranges vary by lab, very low levels may suggest immune deficiencies, and very high levels could indicate chronic infections, certain cancers, or overactive immune responses.

Common Conditions Monitored

IgG tests are often used to diagnose or monitor conditions like HIV, hepatitis, certain autoimmune diseases (e.g., lupus), or to assess immune function in people with weakened immune systems, such as those with HIV/AIDS or after organ transplants.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What causes IgG levels to change?
IgG levels can drop due to immune system disorders, long-term infections, or certain medications that suppress the immune response. They may rise due to chronic infections, autoimmune diseases, or conditions like multiple myeloma. Stress, illness, or recent vaccinations can also temporarily affect IgG levels.
How long does it take to get IgG test results?
Results are usually available within 1–3 business days, depending on your lab and healthcare provider. Some labs may offer same-day or next-day results for urgent cases.
Can IgG levels be affected by diet or supplements?
Diet and supplements generally do not directly affect IgG levels, as IgG is produced by the immune system. However, maintaining a balanced diet supports overall immune function, which may indirectly influence antibody production.
  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