Abstract: Objective　To research the changes of random urine total protein（TP)-to-creatinine（Cr）ratio in 1 d.   Methods　After being determined for 24 h urine protein，a total of 28 patients with renal inadequacy were enrolled. The endogenous creatinine clearance rate（Ccr）was ＞10mL/min. When collecting 24 h urine，about 1.5mL urine was taken out at different point as random urine specimen，and the others were put into the 24 h urine specimen quantitation collections. The values of TP，Cr and TP/Cr ratio in random and 24 h urine specimens were detected and calculated. The 24 h urine specimens with high，middle and low protein concentrations were used to analyze laboratory error [between-run coefficient of variation（CV）]. Results　The CV of TP and TP/Cr ratio with high，middle and low protein concentrations were ＜ 5% in the clinical acceptable range. In 11 of 28（40%）patients，the differentiation between the random urine TP/Cr ratio and 24 h urine TP/Cr ratio wasn′t significant in statistics （P＞0.05）. The 24 h urine protein can be calculated by random urine TP/Cr ratio. After calculating the maximum clinical acceptable range，there were 17（60%）patients whose TP/Cr ratio having a significant differentiation between the random urine TP/Cr ratio and 24 h urine TP/Cr ratio in statistics （P＜0.05）. The patients whose TP/Cr ratio of random urine specimens in 1 d had a highly significant differentiation，evenly reached 30 folds. It was hard to get right amount of 24 h urine protein through predicting random urine TP/Cr ratio. The determination of 24 h urine protein can not be replaced by random urine TP/Cr ratio. To many patients，the urine protein and TP/Cr ratio in random urine specimens showed negative results in some points，although the results of 24 h urine protein were abnormal obviously. Conclusions　These results show that random urine TP/Cr ratio in 1 d has significant changes for many patients. Therefore，24 h TP should be used as an alternative to analyze renal protein.

Key words: Total protein-to-creatinine ratio, Urine, 24 h urine, Random urine