Plasma/Serum Immunoassay for Immunoglobulin G (IgG) Subclass 1 (IgG1) Concentration

What Does This Test Measure?

IgG1 is a subtype of Immunoglobulin G (IgG), an antibody that plays a critical role in defending against infections. This test specifically measures the concentration of IgG1 in your plasma or serum. IgG1 is often the most abundant IgG subclass and is important for long-term immunity.

Why Might You Need This Test?

Doctors may order an IgG1 test to evaluate immune function, diagnose or monitor conditions like immunodeficiency, autoimmune diseases, or certain infections. It can also help assess responses to treatments, such as vaccines or medications that affect antibody production.

Sample Collection and Preparation

For this test, a small amount of blood is drawn from a vein in your arm. The blood is then processed to separate plasma or serum, which is sent to the lab for analysis. No special preparation is needed, but fasting may not be required unless instructed by your healthcare provider.

What Does a Low or High IgG1 Level Mean?

Low IgG1 levels may suggest an immune deficiency, where your body struggles to produce enough antibodies to fight infections. Conversely, very high IgG1 levels could indicate chronic infections, certain autoimmune diseases, or overactive immune responses. Your doctor will interpret results in the context of your overall health and medical history.