Elevated blood creatinine decreased urea nitrogen may be caused by physiological reasons such as their own higher muscle content, or more exercise, etc., but also may be caused by pathological reasons such as renal insufficiency combined with impaired liver function and other diseases. Creatinine is the metabolic end product of creatine in muscle tissue and is closely related to muscle volume, muscle activity and diet. Urea nitrogen is the end product of protein metabolism, and its production depends on dietary protein intake, tissue proteolysis and liver function. When the blood creatinine increase urea nitrogen decrease can be seen in physiological reasons or pathological reasons. 1. Physiological reasons: some patients may have elevated creatinine and decreased urea nitrogen due to higher muscle content, more exercise and long-term low-protein diet, etc. If there is no abnormality in routine urinalysis and ultrasound of the urinary system, and the renal function can be restored to normal after adjusting the way of life, no special treatment is needed at this time. 2. Pathological causes: such as hypertensive renal damage, glomerulonephritis and other causes of renal function impairment, creatinine elevation, if the patient combined with impaired liver function and other causes of urea nitrogen metabolism, urea nitrogen level can be decreased. Blood creatinine elevation urea nitrogen decline may also have other reasons, it is recommended that patients go to the regular hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.