Total Immunoglobulin G (IgG) Subclass 1 and 3 Antibody Concentration (Serum)

What Does This Test Measure?

IgG1 and IgG3 are two subclasses of Immunoglobulin G (IgG), a type of antibody in your blood. These subclasses have distinct roles in immune responses, including fighting bacteria, viruses, and other pathogens. The test quantifies their concentrations to help assess immune function or diagnose conditions like autoimmune diseases, infections, or immune deficiencies.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms or conditions linked to altered IgG subclass levels, such as recurrent infections, autoimmune diseases (e.g., lupus, rheumatoid arthritis), or immune system disorders. It may also be used in research or monitoring immune responses to treatments.

Sample Collection and Testing Process

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum (the liquid part after clotting). The test measures the concentration of IgG1 and IgG3 antibodies using a specialized immunoassay method, which detects and quantifies these proteins with high precision.

What Are Common Reasons for Abnormal Results?

Results may be abnormal if your immune system is overactive (e.g., producing too many antibodies) or underactive (e.g., producing too few). For example, low IgG1/IgG3 levels might suggest immune deficiency, while high levels could indicate chronic infections, autoimmune diseases, or certain medications affecting antibody production.