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Immunoglobulin G (IgG) Subclass 1 (IgG1) Concentration

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

This test measures the amount of a specific type of antibody (IgG1) in your blood, which helps your immune system fight infections and diseases.

Quick summary

["IgG1 is a key part of your immune response and can be checked if you have immune-related conditions or concerns about antibody function."]

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

Key facts at a glance

LOINC
41874-9
Short code
White Birch IgE Qn
Synonyms
White Birch IgE Qn
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 to assess immune function, evaluate immune deficiencies, diagnose autoimmune diseases, or monitor treatment responses in conditions like HIV, lupus, or certain infections. It may also be used in research or specialized diagnostic scenarios.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw from a vein in your arm, similar to other routine blood tests. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results are compared to general population ranges, but individual values can vary based on age, health status, and other factors. Low levels may indicate immune system issues, while very high levels could suggest chronic inflammation or certain diseases.

Common Conditions Monitored

IgG1 levels are often checked in people with immune disorders (like immunodeficiency), autoimmune diseases (like rheumatoid arthritis), or those receiving immune-modifying treatments. It can also help track antibody responses in vaccines or infections.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance of IgG1 levels includes diagnosing or monitoring conditions affecting antibody production, guiding treatment plans for immune-related illnesses, and assessing immune recovery post-infection or post-transplant.

Short name

IgG1 Level

Frequently asked questions

What causes IgG1 levels to change?
IgG1 levels can fluctuate due to infections, chronic illnesses, immune system responses, medications (like steroids), or genetic factors. For example, severe infections or autoimmune diseases may temporarily lower IgG1, while certain treatments might raise it.
How often should I get this test?
Frequency depends on your health condition and treatment plan. Your provider will determine how often to check IgG1 levels, often as part of a broader immune evaluation (e.g., every few months for chronic conditions).
Can diet or lifestyle affect IgG1 levels?
While diet and lifestyle can influence overall immune health, IgG1 levels are primarily tied to immune system activity. However, maintaining a balanced diet and reducing stress may support general immune function, though direct dietary effects on IgG1 are not well-documented.
  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