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Serum Immunoglobulin G (IgG) Level

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 fight infections and is important for long-term immunity.

Quick summary

["IgG helps protect your body from infections and plays a key role in long-term immunity."]

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

Key facts at a glance

LOINC
110133-6
Short code
S pneum Da 14 IgG Msmt Ser
Synonyms
S pneum Da 14 IgG Msmt Ser
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

Why This Test Is Done

Doctors may order an IgG test to check for low or high levels, which can happen due to immune system issues, certain diseases, or after treatments like chemotherapy. It may also be used to monitor immune function in people with conditions like HIV, lupus, or after organ transplants.

What to Expect Before the Test

No special preparation is usually needed. You may have a small needle inserted into a vein (typically in your arm) to draw blood. This process is quick and often causes only minor discomfort.

What the Results Mean

Results are compared to a general reference range for healthy adults. Low IgG levels might suggest weakened immunity, while very high levels could indicate chronic infections, autoimmune diseases, or certain cancers. Your doctor will discuss your specific results with you.

Common Causes of Abnormal Results

Low IgG levels can occur due to immune deficiencies, chronic illnesses, malnutrition, or certain medications. High IgG levels may be linked to chronic infections, autoimmune disorders, or conditions like multiple myeloma.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

What symptoms might indicate you need this test?
Symptoms like frequent or severe infections, slow wound healing, or unexplained fatigue could prompt a doctor to check IgG levels. Children with recurrent infections may also be tested.
How often will I need this test?
The frequency depends on your health condition and treatment plan. Your doctor will determine how often to retest based on your medical history and symptoms.
Can diet affect IgG levels?
Diet can influence overall immune health, but IgG levels are primarily measured in blood and are influenced more by immune system function than diet alone. A balanced diet supports general health, which may indirectly support immune function.
  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