Total IgG Subclass 1 (IgG1) Mass Concentration
This test measures the amount of Immunoglobulin G (IgG) subclass 1, a key part of your immune system that helps fight infections. IgG1 is one of the most abundant antibodies in your blood.
["IgG1 helps protect against bacteria and viruses by marking them for destruction."]
Key facts at a glance
- LOINC
- 99428-5
- Short code
- D microceras IgG4-mCnc
- Synonyms
- D microceras IgG4-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 Is IgG1 and Its Role in Immunity?
IgG1 is a type of antibody (immunoglobulin) produced by your immune system to defend against harmful pathogens like bacteria and viruses. It plays a critical role in long-term immunity by binding to antigens and signaling other immune cells to eliminate them. IgG1 is particularly important for protecting against respiratory and gastrointestinal infections.
Why Might Your Doctor Order This Test?
Your doctor may request this test if they suspect an immune system disorder, such as a condition affecting antibody production (e.g., hypogammaglobulinemia) or if you have symptoms like frequent infections, fatigue, or autoimmune reactions. It can also be part of monitoring for certain diseases like lupus or rheumatoid arthritis.
How Is This Test Performed?
A blood sample is taken from a vein in your arm. The blood is then processed to separate the serum or plasma, where the IgG1 antibody levels are measured using a specialized laboratory technique (likely immunoassay or nephelometry). The result is expressed as a mass concentration of IgG1.
What Do Results Mean?
Results may be compared to a reference range provided by your healthcare provider, though exact values can vary by lab. Low IgG1 levels might indicate immune deficiency, while higher levels could be seen in certain chronic infections or autoimmune conditions. Your doctor will interpret results in the context of your overall health and symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low IgG1 levels can signal an impaired immune response, increasing susceptibility to infections. Conversely, elevated IgG1 may be associated with chronic inflammation, autoimmune diseases, or certain infections. Monitoring IgG1 subclass levels helps diagnose or manage conditions affecting antibody function, such as primary immunodeficiency disorders or certain autoimmune diseases.
Short name
IgG1 Subclass Level
Frequently asked questions
What causes low IgG1 levels?
What are the symptoms of abnormal IgG1 levels?
How is IgG1 tested and monitored?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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