Inclusion Criteria:  (1) Pathological changes of IgAN were confirmed by renal biopsy (2) Age ≥16 years (3) IgA deposition caused by secondary factors such as non-purpura glomerulonephritis, liver cirrhosis, SLE, HIV infection and hepatitis B virus associated nephritis (4) No antibiotics and/or functional foods (probiotics and/or prebiotics) for at least one month prior to sampling (5) No hormone or immunosuppressant treatment in the six months prior to sampling (6) No significant changes in diet or medication for at least one month (7) No other immune or autoimmune diseases, such as systemic lupus erythematosus (8) Signed informed consent  Exclusion Criteria:  Type I or type II diabetes Pregnancy and menstrual period Mental illness and inability to assess follow-up Medically diagnosed intestinal diseases such as irritable bowel syndrome and inflammatory bowel disease Viral hepatitis or other infectious diseases One month before specimen collection, use laxatives including but not limited to polyethylene glycol electrolyte dispersant, enema and other laxatives