An immunoglobulin test measures the level of types of antibodies in the blood. The immune system makes antibodies to protect the body from bacteria, viruses, and allergens. The body makes different antibodies, or immunoglobulins, to fight different things.
If your immunoglobulin level is high, it might be caused by: Allergies. Chronic infections. An autoimmune disorder that makes your immune system overreact, such as rheumatoid arthritis, lupus, or celiac disease