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Total Serum Immunoglobulin G (IgG) Level

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 by fighting off bacteria and viruses."]

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

Key facts at a glance

LOINC
47330-6
Short code
Deprecated S pneum2 IgG 2:1 Ser-Rto
Synonyms
Deprecated S pneum2 IgG 2:1 Ser-Rto
Category
coagulation
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 This Test Measure?

IgG is a type of protein (antibody) produced by your immune system. It’s found in your blood and helps defend against infections. This test checks the total amount of IgG in your serum, which can help doctors assess your immune system’s strength or identify conditions like low immunity or certain immune disorders.

Why Might You Need This Test?

Doctors may order this test if you have symptoms of a weakened immune system, such as frequent infections, unexplained fatigue, or if you’re receiving treatments that affect your immune response (e.g., chemotherapy, steroids). It can also be part of monitoring for conditions like HIV, lupus, or other autoimmune diseases.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into your arm to draw a blood sample. The process is quick and typically painless. If you’re on blood thinners, let your doctor know before the test.

What to Expect During the Test

You’ll sit comfortably while a healthcare provider collects a small amount of blood from your vein. The site may feel slightly sore afterward, but it usually heals quickly. The blood is sent to a lab for analysis.

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 results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing schedule. Your doctor will discuss the results with you during your follow-up visit.
What does a low or high IgG level mean?
A low IgG level might mean your immune system isn’t working as well as it should, which can increase your risk of infections. A high level could be due to chronic illness, certain immune disorders, or other underlying health issues. Your doctor will interpret the results in the context of your overall health and symptoms.
Can I eat or drink before this test?
You can eat and drink normally before this test unless instructed otherwise by your doctor. Avoiding food or fluids for a long time isn’t necessary for blood tests like this one.
  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