IgA nephropathy can be divided into primary and secondary IgA nephropathy. Secondary IgA nephropathy includes, for example, lupus nephritis, allergic purpura nephritis, liver disease-related kidney damage, rheumatoid arthritis kidney damage, and so on. The etiology of primary IgA nephropathy is mainly due to the deposition of a type of immunoglobulin, IgA, in the mesangial area of the glomeruli, leading to a series of immune responses, which in turn cause inflammatory damage, resulting in a chronic glomerulonephritis. This form of IgA nephropathy is mainly related to mucosal immune defense, meaning it is linked to certain infectious factors. Additionally, some patients have high reactivity of their mucosa to certain food antigens, which leads to a series of immune-mediated inflammatory responses.