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Immunoglobulin G (IgG) Subclass 1, Mass Concentration (Serum/Plasma)

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

This test measures the amount of Immunoglobulin G (IgG) subclass 1, a type of antibody in your blood. IgG1 is one of four subclasses of IgG, which play key roles in immune defense.

Quick summary

["IgG1 helps fight infections and is important for long-term immunity."]

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

Key facts at a glance

LOINC
63173-9
Short code
M perniciosa IgG-mCnc
Synonyms
M perniciosa IgG-mCnc
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

What Does This Test Measure?

IgG1 is a subtype of Immunoglobulin G (IgG), the most common antibody in your blood. It is primarily involved in neutralizing toxins and viruses, as well as marking pathogens for destruction by other immune cells. Levels of IgG1 can vary depending on immune response, health status, and certain medical conditions.

Why Might You Need This Test?

Doctors may order this test to evaluate immune function, assess responses to infections or vaccines, or investigate conditions affecting antibody production, such as certain autoimmune diseases or immunodeficiency disorders.

Common Reasons for Testing

This test may be recommended if you have symptoms like frequent infections, unusual fatigue, or if you’re being treated for conditions like lupus, rheumatoid arthritis, or HIV. It can also be part of a broader immune workup.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours if your blood is drawn early in the morning. Wear a loose shirt for easy access to your arm.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG1 Subclass

Frequently asked questions

How Does This Test Help Healthcare Providers?
Low IgG1 levels might suggest immune deficiencies or chronic illnesses that impair antibody production, while elevated levels could indicate certain infections, autoimmune responses, or overactive immune reactions. Monitoring IgG1 helps guide treatment plans for conditions like chronic infections or immune disorders.
What If My Results Are Abnormal?
If your IgG1 levels are outside the expected range, your doctor will discuss potential causes, such as infections, medications, or underlying health conditions. They may recommend further testing or adjustments to your treatment plan.
How Often Should I Get This Test?
The frequency depends on your medical needs. Some patients may need this test yearly or more often if they have chronic conditions like HIV, lupus, or other immune-related illnesses. Always follow your healthcare provider’s guidance.
  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