Skip to content

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

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

This test measures the amount of a specific type of antibody (IgG1) in your blood. Antibodies help your immune system fight infections and other diseases.

Quick summary

["IgG1 antibodies play a key role in defending against certain bacteria and viruses."]

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

Key facts at a glance

LOINC
60465-2
Short code
N men sg W135 IgG Ser IA-mCnc
Synonyms
N men sg W135 IgG Ser IA-mCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 one of four subclasses of Immunoglobulin G (IgG), the most common antibody in your blood. This test specifically looks at the concentration of IgG1, which can vary depending on your immune response or underlying health conditions.

Why Might You Need This Test?

Your healthcare provider may order this test to assess immune function, diagnose or monitor conditions like autoimmune diseases, infections, or certain immune deficiencies, or to evaluate responses to treatments that affect antibody levels.

How Is This Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate the serum, which is sent to a lab for analysis using a specialized immunoassay method to measure IgG1 levels.

What Are Possible Results?

Results are typically reported as a mass concentration value (e.g., grams per liter). Interpretation depends on clinical context, including your symptoms, medical history, and other test results.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG1 Subclass Level

Frequently asked questions

Why was this test ordered?
Your doctor may have ordered this test to investigate symptoms like frequent infections, unusual fatigue, or to monitor conditions such as lupus, rheumatoid arthritis, or other autoimmune diseases. IgG1 levels can also be checked in patients receiving treatments that influence antibody production.
What do abnormal IgG1 levels mean?
Elevated IgG1 levels might indicate an overactive immune response, such as in certain autoimmune conditions or chronic infections. Lower than expected levels could suggest immune deficiencies or conditions that impair antibody production, though results alone are not diagnostic and should be evaluated with other factors.
How often should I expect this test?
The frequency depends entirely on your healthcare provider’s recommendations. Some patients may need this test periodically to monitor their condition, while others may only require it once for diagnostic purposes.
  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