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Serum/plasma concentration of immunoglobulin G (IgG) by nephelometry

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 supports immune defense and is vital for fighting infections over time."]

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

Key facts at a glance

LOINC
40679-3
Short code
T palldm IgG Ser Ql IB
Synonyms
T palldm IgG Ser Ql IB
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ib
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 Is This Test Done?

Your healthcare provider may order this test to check for low or high levels of IgG, which can happen due to immune system issues, certain medical conditions, or after treatments like chemotherapy. It’s also used to monitor immune function in people with weakened immune systems, such as those with HIV/AIDS, cancer, or after organ transplants.

What Does It Measure?

IgG is the most common type of antibody in your blood. It’s produced by your immune system to help fight off bacteria and viruses. Levels can vary based on your health, age, and medical history.

How Is the Sample Collected?

A blood sample is drawn from a vein in your arm. The blood is then sent to a lab for testing. The test measures the concentration of IgG in your serum or plasma.

What Are Possible Results?

Results are typically reported as a concentration value (e.g., grams per liter). While reference ranges can vary by lab, low IgG levels may suggest immune deficiencies, while very high levels could indicate certain autoimmune conditions or infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low IgG levels can indicate a weakened immune system, making you more susceptible to infections. This may be seen in conditions like common variable immunodeficiency (CVID), HIV/AIDS, or after treatments that suppress the immune system. High IgG levels can sometimes be linked to chronic infections, autoimmune diseases, or certain cancers, though they’re less common. Monitoring IgG helps healthcare providers manage immune-related conditions and guide treatment decisions.

Short name

IgG Level

Frequently asked questions

What Causes Low IgG Levels?
Low IgG levels can result from conditions that weaken the immune system, such as HIV/AIDS, certain cancers (like lymphoma), or long-term use of medications that suppress immunity (e.g., steroids). It may also occur in people with autoimmune diseases or those who have had organ transplants.
What Causes High IgG Levels?
High IgG levels are less common but can be linked to chronic infections (like tuberculosis or hepatitis), certain autoimmune diseases (such as rheumatoid arthritis), or some cancers. Rarely, it may also be a side effect of certain medications or immune system overactivity.
How Often Should I Get This Test?
The frequency depends on your medical condition and treatment plan. If you have an ongoing health issue affecting your immune system, your doctor may recommend regular monitoring. For routine health checks, this test is usually not part of standard screening unless symptoms suggest an immune issue.
  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