REN and nephrotic syndrome: The treatment of IgAN children with nephrotic syndrome emphasizes the control and elimination of proteinuria, and the drugs for the treatment are mainly divided into two categories, including non-immunosuppressive drugs, such as the renin–angiotensin system inhibitors, calcium antagonists, and fish oil [30], whose clinical effect is not ideal, and immunosuppressants such as corticosteroid and cytotoxic drugs.