Complement is usually an anti-inflammatory factor that occurs in response to inflammation, so the most common cause of increased total complement is infectious factors. Whether the body is infected by bacteria, viruses, fungi or other pathogens such as mycoplasma and chlamydia, there will be an increase in the body’s inflammatory factors, such as leukotrienes, bradykinin, prostacyclin, tumor necrosis factor, etc., and also stimulate the increase in the total complement, so the most common reason for the increase in total complement is the production of inflammatory factors and inflammatory reactions in the body. In addition, in non-infectious inflammatory reactions, there will also be increased complement, immune inflammatory diseases such as rheumatoid arthritis, rheumatoid arthritis, dermatomyositis, or connective tissue inflammation, such as systemic lupus erythematosus, desiccation syndrome and other immune system disorders, there will be an increase in the total complement. Specific rare diseases such as AIDS, tumors, and severe anemia can also lead to increased total complement.