Nephrotic syndrome (NS) is not an independent disease, but rather, it is a group of clinical syndromes caused by a variety of etiologies, mainly the following manifestations: ① large amount of proteinuria (24h urine protein quantification > 3.5 g). ② Hypoproteinemia (serum albumin <30g/L) ③ Hyperlipidemia. ④Oedema may be mild or severe, or even no edema. It is usually called "three highs and one low". There are various causes of nephrotic syndrome, which can be divided into primary nephrotic syndrome and secondary nephrotic syndrome. Primary nephrotic syndrome is more common in children and adolescents, and renal biopsies are mainly microscopic lesions, followed by focal segmental glomerulosclerosis, most of which are sensitive to hormone therapy, but are prone to relapse. In adults, the causes of the pathological types of nephrotic syndrome are more complex, and the primary pathological types are mostly membranous nephropathy, focal segmental glomerulosclerosis, etc. Most of them are not sensitive to hormone therapy.