Comparison between IDMS-traceable Jaffe and enzymatic creatinine assays for estimation of glomerular filtration rate by the CKD-EPI equation in healthy and diabetic subjects.

Objectives: The aim of this paper was to compare the agreement between creatinine measured by Jaffe and enzymatic methods and their putative influence on eGFR as calculated by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation in healthy and diabetic individuals.

Design And Methods: Cross-sectional study conducted in 123 adult southern Brazilians with GFR>60 mL/min/1.73 m² (53 patients with type 2 diabetes, 70 healthy volunteers). Mean age was 49±16 years (range of 19-86). Most were female (55%) and white (83%). Creatinine was measured by a traceable Jaffe method (Modular P, Roche Diagnostic) and by an enzymatic method (CREA plus, Roche/Hitachi 917). GFR was measured by the ⁵¹Cr-EDTA single-injection method.

Results: Serum creatinine measured by the Jaffe and enzymatic methods was similar in healthy subjects (0.79±0.16 vs. 0.79±0.15 mg/dL, respectively, P=0.76), and diabetic patients (0.96±0.22 vs. 0.92±0.29 mg/dL, respectively, P=0.17). However, the correlation between the two methods was higher in the healthy group (r=0.90 vs. 0.76, P<0.001). The difference between Jaffe creatinine and enzymatic creatinine was <10% in 63% of cases in the healthy group and 40% of cases in the diabetes group (P=0.018). In the subset of patients with diabetes, eGFR based on enzymatic assay results showed better agreement with measured GFR than did eGFR based on Jaffe results.

Conclusion: Jaffe and enzymatic creatinine methods show adequate agreement in healthy subjects, but in the presence of diabetes, the enzymatic method performed slightly better.