Whether creatinine 420μmol/L can be restored to normal depends on the cause of creatinine elevation, if it is caused by acute renal insufficiency, most of it can be restored to normal after active treatment, if the patient is chronic renal insufficiency, it is generally difficult to cure. Acute renal insufficiency is often caused by a sudden drop in glomerular filtration rate, if the patient corrects the reversible causes as soon as possible, the renal function can be restored to normal after active treatment, often using glucocorticoids such as prednisone, etc.; antibiotics such as amoxicillin and so on. However, there are some patients who are not treated in time, and the renal function damage is more serious and can not be restored to normal. When the blood creatinine of chronic renal insufficiency patients is 420μmol/L, it indicates that it has entered the period of renal failure, and it is often treated with diuretics and antihypertensive drugs, such as furosemide, enalapril, valsartan, etc., but it will not return to normal in general. If the blood creatinine level continues to rise, or even develops to uremia, it can only be treated by hemodialysis, peritoneal dialysis, kidney transplantation and so on. Patients are advised to take treatment as early as possible and take medication strictly according to the doctor’s prescription to avoid irreversible kidney damage.