Chronic kidney disease is defined as kidney damage or glomerular filtration rate (GFR) consistently <60 ml/min/1.73m²≥3 months as confirmed by renal biopsy or detection of markers of damage, according to the definition approach proposed by the American Kidney Foundation (NKF) K/DOQI working group. Markers of renal impairment include proteinuria, abnormal urine test strips or urine sedimentation, or abnormal renal imaging.GFR can be imputed by a formula based on serum creatinine and several other variables including age, sex, race, and body surface area. The staging of chronic renal insufficiency in China is usually divided into four stages according to the scoring criteria of the symposium on typing, treatment and efficacy determination of primary slow glomerular diseases held in Anwei Taiping in June 1992 by the Nephrology Specialty Group of the Editorial Committee of the Chinese Journal of Internal Medicine: Stage I: compensatory period of chronic renal insufficiency: when the renal unit damage does not exceed 50% of normal (GFR 50~80 ml/min) renal function Because it can compensate without metabolite retention such as urea nitrogen (BUN), blood creatinine (Scr) can maintain normal levels, (blood creatinine 133~177ummol/l,1.5~2.0mg/dl), clinically usually asymptomatic. The second stage: chronic renal insufficiency decompensation stage: renal unit damage remaining renal function is less than 50% of normal (GFR20~50ml/min) blood creatinine reaches 177~442umol/l (2~5mg/dl), urea nitrogen, rise more than 7.1mmol/l, (20mg/dl), clinical appear weakness, mild anemia, loss of appetite and other systemic symptoms. Stage 3: renal failure: blood creatinine reaches 442~707ummol/l (5~8mg/dl), creatinine clearance rate drops to 10~20ml/min, urea nitrogen rises to 17.9~28.6mmol (50~80mg/dl). Patients develop severe anemia, metabolic acidosis, disorders of calcium and phosphorus metabolism, disorders of water-electrolyte metabolism, etc. Stage 4: Uremic phase: blood creatinine reaches 707ummol/l (8mg/dl) or more, creatinine clearance is below 10ml/min, urea nitrogen is above 28.6mmol/l (80mg/dl), acidosis symptoms are obvious, and symptoms of all systems are severe. The American Kidney Disease Foundation usually divides chronic kidney disease into five stages according to glomerular filtration rate: CKD1 stage: renal damage, normal or elevated GFR, GFR ≥ 90 (ml/min/1.73m²) (hereinafter omitted); CKD2 stage: renal damage, mildly decreased GFR, GFR located at 60~80; CKD3 stage: moderately decreased GFR, GFR located at 30 ~59; CKD stage 4: moderate decrease in GFR, GFR located at 15-29; CKD stage 5: renal failure, GFR <15 or dialysis.