Nephrotic syndrome (NS) can be caused by a variety of etiologies and is characterized by a group of clinical syndromes with increased glomerular basement membrane permeability, manifested by massive proteinuria, hypoproteinemia, high edema, and hyperlipidemia. 1. Infections Loss of IgG and complement components in the urine, decreased IgG synthesis to hypoimmune function; cellular immune dysfunction; protein malnutrition; edema; immunosuppressant application. Respiratory tract infections are the most common, followed by skin and urinary tract infections and primary peritonitis. Peritonitis is common in children with ascites, and the causative organisms are podococci (such as Streptococcus pneumoniae) and Escherichia coli, with clinical manifestations of fever, abdominal pain and abdominal distension, and abdominal muscle tension and rebound pain may not be significant. 2, electrolyte disorders hyponatremia: long-term salt prohibition, excessive application of diuretics, infection (increased secretion of stress antidiuretic hormone), diarrhea, vomiting, manifested as anorexia, weakness, laziness, drowsiness, decreased blood pressure, shock, convulsions. Hypokalemia: caused by diuretic application or hormonal diuresis, nausea, diarrhea and neglect of potassium supplementation. Hypocalcemia and osteoporosis: loss of vitamin D-binding protein from urine, reduced D levels, malabsorption of intestinal calcium, reduced sensitivity of bones to the regulatory effects of parathyroid hormone, hyperparathyroidism, etc., plus the application of hormones. 3, hypercoagulable state, thrombosis Causes: increased synthesis of coagulation factors by the liver; loss of anticoagulation factor III in the urine; hyperlipidemia blood viscosity, slow blood flow, increased platelet aggregation; activation of the endogenous coagulation system by infection or damage to the vessel wall; application of diuretics, reduced blood volume, blood concentration; hormone application to promote hypercoagulation, etc. Renal vein thrombosis is the most common: sudden back pain or abdominal pain, non-glomerular hematuria, oliguria, and even acute renal failure, with enlarged kidneys on one or both sides visible on ultrasound and thrombus visible in large vessels. In recent years, it is not uncommon to report pulmonary embolism, but also lower limb thrombosis and cerebral embolism. 4.Adrenal crisis Long-term application of large doses of hormones, the pituitary-adrenal cortex axis is inhibited, such as withdrawal of drugs too quickly, sudden interruption of medication, the occurrence of stress conditions and not timely increase the dose, the child can suddenly appear shock performance, if not timely rescue and easy to cure death. 5, acute renal failure The possible causes include: prerenal renal failure due to low blood volume; serious glomerular lesions, significant hyperplasia, GFR significantly decreased; severe interstitial edema, protein tubular obstruction of the renal tubules, resulting in the proximal tubules and the glomerular capsule hydrostatic pressure increased, resulting in a decrease in effective glomerular filtration.