The S-IgG test checks the levels of antibodies called immunoglobulins in your bloodstream. Antibodies are proteins made by your immune cells to fight off pathogens like bacteria, viruses, mold, and even food proteins.
The immunoglobulin test can show whether there's a problem with your immune system. IgG is the most common antibody in your bodily fluids. It helps to protect you against infection and food proteins by remembering previous infections and food reactions.
Read more about the S-IgG blood test.