The etiology of chronic nephritis has now been clinically identified, usually as an autoimmune disease. There are also the following factors that lead to this autoimmune reaction: 1. Infection: Clinically common infections, especially repeated chronic infections, such as repeated upper respiratory tract infections or repeated gastrointestinal infections, diarrhea in patients, chronic hepatitis virus infections, etc. There are also some patients whose foci of infection are not obvious, but there is also an immune response in the body, which then causes an autoimmune response that can cause chronic nephritis. 2. Allergic reactions: some common causes, such as patients to food, certain drinks or to a certain component of the air caused an immune response, clinically common, such as allergic purpura, some patients can appear purpura nephritis. So, in summary, the causes of chronic nephritis are related to the autoimmune reaction in the body.