Both urea nitrogen and creatinine are more important indicators, both represent the function of the kidneys, especially creatinine. Urea nitrogen can be affected by eating large amounts of protein, i.e. urea nitrogen is related to diet. But creatinine can fully express the kidney function without being affected by diet. So although both are indicators reflecting the kidney, creatinine is not affected by diet, so it can usually reflect kidney function more accurately. If the above indicators are elevated, it usually indicates renal insufficiency, i.e. renal failure, which may have azotemia stage and uremia stage in advanced stage, and may need dialysis treatment as the condition develops, choosing peritoneal dialysis or hemodialysis, etc. Therefore, we should be highly alert to the elevated values of all the above indicators, whether there is renal insufficiency, but also to monitor the morphology of the kidneys, the size of the kidneys, the renal vasculature, blood pressure, etc.