High urea is usually very much related to a high protein diet, and some of it is caused by a decrease in the detoxification ability of the kidneys. Urea is a product of protein metabolism, so when urea is elevated, first review whether it is a high protein diet recently, such as eating more meat, dairy, eggs, soy products recently, these foods will be metabolized into urea after entering the body, and urea nitrogen will naturally rise, but this situation will only lead to an increase in urea, while creatinine will not rise. If the kidney function test reveals that creatinine is also elevated, it should be considered that the kidney’s detoxification ability is reduced, not caused by diet. Decreased kidney detoxification ability is often called renal failure. There are many reasons for renal failure, such as the short-term application of a large number of nephrotoxic drugs such as non-steroidal anti-inflammatory drugs, or the gradual development of chronic kidney disease, which can lead to a decrease in the detoxification ability of the kidneys. In addition to considering the above factors, it is also necessary to consider the presence of decreased urine or intestinal bleeding.