Creatinine value in renal failure is usually above 110umol/L. Since the testing method of each hospital is different, the values are more or less different, some are above 90umol/L, some are above 130umol/L. Therefore, to evaluate whether the creatinine value is high or low, it is necessary to combine the reference value of the test at the local hospital. In addition, there are some limitations in using creatinine value to evaluate kidney function. Because creatinine is a product of muscle metabolism, it is influenced by the patient’s age, gender, weight and other factors. So in order to exclude the influence of these factors, glomerular filtration rate is mostly used clinically to evaluate renal function, and glomerular filtration rate is a little more accurate than creatinine value. In general, if the glomerular filtration rate is lower than 90 ml/min, the presence of renal failure is considered, and the next step is to actively search for the cause of renal failure.