Immunoassay for Immunoglobulin G (IgG) Subclass 1 (IgG1) in Serum

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

This test measures the level of Immunoglobulin G1 (IgG1), one of the main types of antibodies in your blood. IgG1 helps protect your body from infections and plays a role in immune responses.

Quick summary

["IgG1 levels can help diagnose or monitor certain immune conditions or infections."]

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

Key facts at a glance

LOINC: 62458-5
Short code: C immitis IgM Ser Ql ID
Synonyms: C immitis IgM Ser Ql ID
Category: chemistry
Sample: serum
Container: Red-top tube (SST)
Units: N/A
Fasting: false
Population: adult
Sex: all
Age range: 18–65 years
Method: immune-diffusion
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), which is the most common antibody in your blood. This test specifically looks at the concentration of IgG1 antibodies. IgG1 is particularly important in fighting bacterial and viral infections and is involved in allergic reactions and immune responses.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms or conditions linked to abnormal IgG1 levels, such as chronic infections, autoimmune diseases, or certain immune deficiencies. It may also be used to monitor treatment responses in conditions like rheumatoid arthritis or other immune-related illnesses.

Sample Collection and Preparation

A blood sample is taken from a vein in your arm. The blood is processed to separate the serum (the liquid part without blood cells), which is then tested for IgG1 levels using an immunoassay method.

Common Reasons for Testing

This test might be recommended if you have recurrent infections, unexplained fatigue, or symptoms like joint pain, skin rashes, or frequent colds. It can also be part of a broader evaluation for conditions affecting the immune system.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG1 Subclass Test

Frequently asked questions

What Are Normal IgG1 Levels?

There are no specific reference ranges provided here as they can vary by lab and individual. Your results will be compared to your own baseline or to ranges relevant to your specific health condition.

How Does This Test Differ from Other Antibody Tests?

Unlike general IgG tests, this test focuses specifically on IgG1, which is one of four subclasses of IgG antibodies. Each subclass has distinct roles in immunity, and measuring IgG1 can give more targeted information about your immune response.

Can Diet or Supplements Affect IgG1 Levels?

Dietary factors or supplements may indirectly influence immune function, but they do not directly affect IgG1 levels. If you have concerns about your diet or supplements, talk to your healthcare provider.

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