Complement and Immunoglobulin Tests

Complement and Immunoglobulin Tests help assess how effectively the immune system recognizes threats, produces antibodies, and activates complement proteins to control infection and inflammation. This category explains common and specialized blood tests in clear, practical language, including immunoglobulin panels for IgG, IgA, IgM, IgE, and IgG subclasses, as well as complement C3, C4, C1q, CH50, and AH50 testing. Explore what high, low, or abnormal results may mean in the context of recurrent infections, autoimmune disease, hereditary angioedema, kidney disorders, immune deficiency, allergy, and inflammatory conditions. Detailed guides also cover C1 esterase inhibitor antigen and function, terminal complement components, mannose-binding lectin, and primary immunodeficiency test panels. You will also find explanations of vaccine antibody titers, including pneumococcal, tetanus, and diphtheria antibodies, used to evaluate immune protection and vaccine response. For suspected plasma cell or antibody-production disorders, the category covers serum protein electrophoresis, immunofixation, free kappa and lambda light chains, and the kappa/lambda ratio. Each guide explains the test’s purpose, result patterns, limitations, related symptoms, and possible follow-up testing, while emphasizing that laboratory findings must be interpreted alongside medical history and clinical evaluation.