Comparative study of serum creatinine measurement by Jaffe’s and enzymatic method in patient samples.

Background. Creatinine-based equations are used to calculate estimated Glomerular Filtration rate (eGFR) and to evaluate renal function. Accurate measurement of creatinine is thus of utmost importance to identify and classify kidney diseases. The two most used methods available currently for measuring creatinine are Jaffe method (Chemical based) and enzymatic methods have their inherent limitations. Methodology. Serum creatinine was measured in the serum sample of 100 patients using Jaffe’s and enzymatic methods. Estimated Glomerular Filtration Rate (eGFR) was calculated & compared using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for both sets of data. This data was used to assess the probability of misclassification of chronic kidney disease at various clinical decision limits. Results. A total of 100 paired data for serum creatinine levels measured by chemical & enzymatic method were obtained. The mean serum creatinine by Jaffe’s method was 0.914 mg/dL and by enzymatic method was 0.596 mg/dL. Of the total 100 patients, 63 patients (63) % were found to fall under the same CKD staging category irrespective of the method used. However, there were 37 patients (37%) that were falling into different CKD staging category. Conclusion. The serum creatinine assays needs careful interpretation of results considering the use of different methodologies (Chemical or enzymatic) used for analysis or for the data obtained from different laboratories. Since, creatinine value is used for eGFR calculation and subsequently for staging in CKD patients, any variability has the potential to affect the course of patient care. A good understanding of relative performance of various assays in routine biochemical analysis is imperative so that a right balance be struck between the cost and the accuracy of an assay.