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The aim of this study is to compare analytical performance characteristics and also the patient results obtained from both Modified Jaffe’s kinetic and Enzymatic Trinder methods for serum creatinine so as to identify risk zone, if present, within the measurement range. Serum creatinine was measured on 206 left-over serum samples by Modified Jaffe’s kinetic and Enzymatic Trinder methods. For analytical performance comparisons, limit of detection(LOD), limit of quantification(LOQ), linearity, measuring range, intra and inter-assay CV were measured and compared. Statistical comparisons were done by Pearson‘s correlation coefficient and Bland-Altman tests. For Enzymatic Trinder and Modified Jaffe’s kinetic methods, LODs for serum creatinine were 0.01 & 0.02 mg/dl respectively; LOQs were 0.04 & 0.06 mg/dl respectively; linearity were upto 55 mg/dl & 30 mg/dl respectively. Correlation coefficient was high (r=0.99); intra and inter-assay CV measurements were acceptable. However, CV was lower for Enzymatic Trinder method. Bland-Altman plot showed that more than 95% data points lie within ± 1.96 SD limit of mean difference value (0.16). Average discrepancy (ie. bias) was 0.16 mg/dl across whole measurement range. However, at low concentrations, Modified Jaffe’s kinetic method gave higher values indicating systematic bias, thereby forming a “risk zone” in measurement range. Analytical performance requirements were met by both methods for routine use and good agreement exists between them. However, better performance was not shown by Modified Jaffe’s kinetic method at low concentrations. Such a “risk zone” needs to be identified by laboratories for accurate reporting of creatinine results.
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