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Total 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 and is important for long-term immunity.

Quick summary

["IgG levels help assess immune function and identify potential immune deficiencies or infections."]

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

Key facts at a glance

LOINC
46198-8
Short code
M pneumo IgG Ser Ql
Synonyms
M pneumo IgG Ser Ql
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

Why This Test Might Be Ordered

Your healthcare provider may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It could also be done to monitor immune responses in conditions like autoimmune diseases or after certain treatments, such as chemotherapy or organ transplants.

What to Expect Before the Test

No special preparation is needed for this blood test. You may be asked to fast for 8–12 hours before the draw if your lab requires it, but this is not always the case. Bring your test list and any medications to the appointment.

How the Test Is Performed

A healthcare professional will insert a needle into a vein in your arm to draw a small amount of blood. The blood is then sent to a lab for analysis. The process usually takes a few minutes and may cause a brief pinch or discomfort.

What the Results Mean

Results are compared to standard ranges for IgG levels in healthy adults. Low levels may suggest immune system issues, while very high levels could indicate chronic infections, certain diseases, or overproduction of antibodies.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

How long does it take to get my IgG test results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your healthcare provider will discuss the findings with you during your follow-up visit.
Can I eat or drink before this test?
Most IgG tests do not require fasting, but always follow your lab’s specific instructions. If fasting is required, avoid caffeine or heavy meals 8–12 hours before the draw.
What does it mean if my IgG level is low?
A low IgG level may indicate an immune deficiency, such as a congenital disorder or acquired conditions like HIV/AIDS. Your provider may recommend further testing or adjustments to treatment based on the cause.
  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