The medical term CKD refers to chronic kidney disease, a concept developed by the American Kidney Disease Foundation. Chronic kidney disease is defined as kidney damage or a glomerular filtration rate below 60 ml/min per body surface area for at least 3 months. Renal damage includes abnormalities in renal pathology and laboratory indicators of renal damage, such as blood, urine and imaging. According to the different clinical manifestations, chronic kidney disease can be divided into five stages: stage I is a period of relatively mild glomerular damage, when the glomerular filtration rate is greater than or equal to 90 ml/min; stage II lesions are relatively aggravated, with a glomerular filtration rate of 60-89 ml/min; stage III glomerular filtration rate is moderately reduced, mostly in the range of 30-59 ml/min; stage IV glomerular filtration rate decreases to 15-29 ml /min; end-stage renal disease, that is, chronic kidney disease stage V, glomerular filtration rate is less than 15ml/min, also known as the uremic phase.