Urea nitrogen is high and creatinine is normal, mostly due to the recent high protein diet or low blood pressure caused by the following: the first situation is the recent consumption of high protein diet, urea nitrogen is the product of protein metabolism, if the patient’s recent intake of protein is more, such as eggs, duck eggs, lean meats, fish, soy products, etc., metabolized into a urea will be excreted through the kidneys, but more than the excretory capacity of the kidneys, urea nitrogen will be high. The urea nitrogen will be high. The second situation is the lowering of blood pressure, the possible causes are vomiting, diarrhea, excessive sweating or taking too much antihypertensive drugs, which will lead to renal artery constriction, renal perfusion is insufficient, the detoxification capacity of the kidneys will be reduced, and the excretion of urea will be reduced. For the first cause, only dietary control and dynamic review are needed, while for the second cause, the reason for the decrease in blood pressure needs to be clarified and corrected at the same time, and then the urea level should be reviewed dynamically.