Kidney function mainly looks at creatinine and urea nitrogen. The indicators of kidney function generally include three creatinine, urea nitrogen and uric acid, and the first two are the main indicators. Creatinine is a product of muscle metabolism, while urea nitrogen is a product of protein metabolism. These two substances have a common feature, that is, they are filtered through the kidneys, while very little is reabsorbed through the kidneys, so they can reflect the detoxification ability of the kidneys. If these two indicators are reduced, generally speaking, and the diet is too controlled, poor nutrition, there is a very big relationship, the clinical significance is not very big, we are generally not very concerned. If these two indicators are elevated, the clinical significance will be greater, indicating renal failure. Of course, renal failure is caused by acute factors and chronic factors, and the prognosis of these two diseases is different. Therefore, when elevated creatinine and urea nitrogen are found, it is recommended to continue to improve the relevant tests to clarify the underlying causes and treat them from the etiology, which can prevent or delay the entry into the uremic phase.