Blood creatinine 400μmol/L is commonly found in acute and chronic kidney diseases, such as urinary tract obstruction, diarrhea, gastrointestinal bleeding and chronic glomerulonephritis, hypertensive nephropathy, etc. Whether it is caused by acute or chronic kidney disease, blood creatinine 400μmol/L is generally more serious. Serum creatinine value is an indicator reflecting the glomerular filtration function. Due to the strong compensatory ability of the kidneys, blood creatinine will be elevated only when the renal function is severely damaged. A higher elevation of blood creatinine 400 μmol/L suggests more serious kidney injury. If it is caused by acute kidney injury, common causes such as urinary tract obstruction, diarrhea, gastrointestinal bleeding, medication kidney injury, etc., the patient may appear in the short term oliguria, anuria, need to target treatment for specific causes, treatment is not timely, serious patients will even be life-threatening, so generally more serious. Chronic kidney diseases such as chronic glomerulonephritis, hypertensive nephropathy, diabetic nephropathy and other causes of blood creatinine 400 μmol / L, the patient may not have obvious symptoms, but if not actively treated, the patient may eventually lead to uremia, a serious impact on the patient’s life expectancy, and therefore also more serious. Once the blood creatinine 400μmol/L is found, you need to consult the nephrology department of the regular hospital immediately, complete the relevant examinations, and follow the doctor’s instructions for standardized treatment after a clear diagnosis.