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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.

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
8027-5
Short code
Deprecated S pneum14 IgG Ser IA-aCnc
Synonyms
Deprecated S pneum14 IgG Ser IA-aCnc
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 the most abundant antibody in your blood, produced by your immune system to fight infections. It helps remember past infections and provides long-term protection. This test checks the concentration of IgG in your serum, which can help doctors assess your immune response and identify potential deficiencies.

Why Might You Need This Test?

Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, slow wound healing, or unexplained fatigue. It can also be used to monitor conditions like HIV, certain autoimmune diseases, or after receiving certain treatments that affect the immune system.

What to Expect Before the Test

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

What to Expect During the Test

The blood sample will be sent to a lab for analysis. The results will be reviewed by a healthcare professional to determine if your IgG levels are within a normal range or if further evaluation is needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What Are Common Causes of Abnormal IgG Levels?
IgG levels can be lower than normal in people with immune deficiencies, such as severe combined immunodeficiency (SCID) or HIV/AIDS, or after certain treatments like chemotherapy. High levels may be seen in chronic infections, certain autoimmune diseases, or during pregnancy.
How Long Does It Take to Get Results?
Results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your doctor will discuss the results with you during your follow-up visit.
Can Diet or Lifestyle Affect IgG Levels?
Dietary factors like protein intake may indirectly support immune function, but they do not directly influence IgG levels. Stress, poor sleep, or chronic illness can sometimes impact immune responses, but IgG levels are primarily determined by your body’s immune system and medical conditions.
  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