Nephrotic syndrome is a group of specific types of nephritis, with massive proteinuria, high edema, high cholesterol and low proteinemia (“three highs and one low”) as the main clinical manifestations, which can be caused by a variety of reasons. 1. Massive proteinuria: urine protein (3+C4+), 24-hour urine protein quantification greater than 50 mg per kg per day; 2. High edema: edema mostly starts in the eyelids and face and gradually spreads to the whole body, with depressed edema pressure, which may be accompanied by pleural fluid, ascites and scrotal edema. 3, hypercholesterolemia: serum cholesterol greater than 220 mg/dL, in infants greater than 200 mg/dL. 4, hypoproteinemia: serum albumin less than 30 g/L, in infants less than 25 g/L.