Comparison of two methods in detecting serum creatinine

Objective: To analyze the correlation between creatinine enzyme and dry chemistry method in detection of blood plasma creatinine and to estimate the bias between the two methods.Methods: According to the guideline approved by the National Committee for Clinical Laboratory Standards(NCCLS),48 patients’ samples were analyzed in 6 operating days and each sample was analyzed in duplicate using both creatinine enzyme and dry chemistry methods.The dry chemistry method was evaluated with creatinine enzyme method acting as control.The duplicates were assessed with each method within the same run.The coefficient of correlation was calculated as well as the bias.Results: There was a significant difference between the enzyme and dry chemical method in blood creatinine determination(P<0.001),but they had a positive relativity;its linear equation was Ŷ=-3.449 4+0.929 6X and r²=(0.993 2).When the concentration of creatinine was 100 μmol/L,500 μmol/L and 900 μmol/L,the relative bias of dry chemistry method was 10.5%,7.7%,7.4%.Conclusions: The results were significantly different in detection of serum creatinine with the two different methods,but its correlation was good.The Laboratory must establish its own reference ranges for different methods or practice an emendation between the two methods.