High blood urea nitrogen and creatinine may be caused by physiological factors such as increased exercise, or pathologic factors such as acute kidney injury and chronic renal insufficiency. 1. Physiological factors: If the patient’s recent activity is large, the muscle produces more metabolites, or if the patient consumes more meat recently, it may cause the blood urea nitrogen and creatinine to be higher than the normal value. After resting or adjusting the diet structure of the patient can be restored to normal values, without special treatment. 2. Pathologic factors: (1) Acute kidney injury: acute kidney injury caused by various reasons, such as massive diarrhea, extensive burns, or trauma leading to blood volume insufficiency, may result in higher than normal urea nitrogen and creatinine. After correcting reversible causes, blood urea nitrogen and creatinine values may decrease or even return to normal. (2) Chronic renal insufficiency: such as chronic nephritis, chronic pyelonephritis and other diseases leading to chronic renal insufficiency, renal function progression, blood urea nitrogen and creatinine higher than normal values, at this time, we need to actively treat the primary pathology to delay the progression of renal function. If patients find that blood urea nitrogen and creatinine are high, it is recommended to go to regular hospitals in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.