Urea nitrogen and blood creatinine are both high, if belongs to physiological increase, generally not serious; if belongs to the pathologic increase in acute kidney injury caused by the elevation, generally not serious, if chronic elevation, it is more serious. 1. Physiological elevation: generally not serious and no special treatment is needed. Such as after strenuous exercise, eating a lot of meat food, emotional stress and anxiety, etc., may lead to high creatinine and urea nitrogen, but physiological factors caused by high creatinine and urea nitrogen will not affect the renal function and renal excretion, so it is not serious, and it is recommended to have regular review to assess the renal function. 2. Pathological increase (1) If creatinine and urea nitrogen are pathologically elevated, the excretion of renal function has been changed. If the increase is acute, such as diarrhea, infection and other causes of blood creatinine, urea nitrogen transient increase, after removing the cause and symptomatic treatment, generally can be recovered, so it is not serious. However, some of them can not be fully recovered, leaving behind chronic renal insufficiency, which is relatively more serious. (2) If the elevation of creatinine and urea nitrogen is chronic, i.e. chronic renal failure, it will be more serious, and if it is not treated in time, the condition will be further aggravated and may develop into uremia. If creatinine and urea nitrogen are found to be high, it is recommended to go to the hospital regularly to check the renal function, to know the damage of renal function, and once abnormalities are found, standardized treatments should be strictly followed by doctors’ instructions.