Immunoglobulin G (IgG) Substance Concentration in Serum/Plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of Immunoglobulin G (IgG), a type of antibody found in your blood. IgG helps protect your body from infections and is the most common antibody in your immune system.

Quick summary

["IgG levels help assess your immune system's strength and detect potential deficiencies or excesses."]

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

Key facts at a glance

LOINC: 42207-1
Short code: IgG CSF/SerPl
Synonyms: IgG CSF/SerPl
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 like frequent infections, unexplained illnesses, or if you’re being evaluated for conditions like immunodeficiency, chronic infections, or certain autoimmune diseases. It may also be checked before certain treatments, such as chemotherapy, to ensure your immune system is functioning properly.

What to Expect Before the Test

No special preparation is needed for this test. You may have a blood draw from a vein in your arm. If you’re on blood thinners, let your provider know beforehand to avoid unusual bleeding.

What the Results Mean

IgG levels can vary based on age, overall health, and medical conditions. Low levels may indicate a weakened immune system, while very high levels could suggest chronic infections, certain cancers, or other health issues. Your provider will discuss the results with you in the context of your health history.

Low IgG levels can be linked to conditions like Common Variable Immunodeficiency (CVID), HIV/AIDS, or other immune deficiencies. High IgG levels may be seen in chronic infections (e.g., hepatitis, tuberculosis), certain cancers (e.g., multiple myeloma), or autoimmune diseases like lupus.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Level

Frequently asked questions

How often will I need this test?

The frequency depends on your health condition and treatment plan. If you have an ongoing medical issue, your provider may recommend regular monitoring. If this test is part of routine check-ups, it may be done less often, such as every few years.

What if my IgG level is outside the normal range?

If your IgG level is low, your provider may recommend additional tests to check for underlying causes, such as immune system disorders. If it’s high, further evaluation might be needed to determine if it’s due to infection, disease, or another factor. Your provider will guide you on next steps based on your results.

Can diet or lifestyle affect IgG levels?

Diet and lifestyle factors like nutrition, stress, and overall health can influence immune function, but they don’t directly affect IgG levels. Maintaining a balanced diet and managing stress can support your immune system, though this test measures IgG specifically in your bloodstream.

Sources

1
MedlinePlus — Laboratory TestsSource
2
Lab Tests OnlineSource
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