Abstract: Objective To investigate the difference of serum urea（UREA）,creatinine （CREA）and urea removal rate（URR）between urease rate method and dilution mode and its effect on the evaluation of dialysis adequacy. Methods one hundred and forty-eight inpatients（UREA level basically uniform covering linear range） in our hospital were enrolled as group A and one hundred and thirty-four dialytic patients were enrolled as group B. The level of UREA and CREA levels in group A were detected in original concentration and 5-fold dilution mode. The levels of UREA in serum of group B before and after dialysis were detected by original concentration,3-fold dilution mode and 5-fold dilution mode respectively. We calculated the URR of each patient and compared the difference of urea,URR and dialysis adequacy evaluation. Results The results of full-range UREA detected by dilution mode were significantly different from those of original mode,and the relative error was positively correlated with the level of UREA（r=0.57,P<0.05）,while the CREA level has no effect（P>0.05）. In group B,the levels of UREA and URR detected by dilution modes were significantly higher than those of original mode （P<0.05）.The percentage of dialysis adequacy evaluated by dilution modes were significantly higher than that of original mode（P<0.01）,and there was no significant difference among different dilution modes（P>0.05）. Conclusion Urease rate method in dilution mode affects the detection results of UREA,which leads to the increase of URR in dialysis patients and reduces the accuracy of dialysis adequacy evaluation.

Key words: UREA, Urea removal rate, Dialysis adequacy evaluation