Estimated Glomerular Filtration Rate using Creatinine Levels Determined by Enzymatic and Jaffe Kinetic Methods

Background and Objectives: The measurement of serum creatinine is important because it is being used as an indicator of renal function. The aims of this study were to compare the levels of creatinine, to evaluate the estimated glomerular filtration rate (eGFR) and to find the consistency between Jaffe kinetic and enzymatic method. Methods: One hundred and fifteen serum samples with either low or high creatinine levels, which analyzed by enzymatic method, were collected from both male and female patients at Clinical Chemistry Unit, Srinagarind hospital. The sera were further categorized by gender and creatinine level. Serum samples from females were classified by creatinine levels of ≤ 0.7 and >0.7 mg/dL and from male were classified by creatinine levels of ≤0.9 and >0.9 mg/dL. Results: We found a statistically significant of positive correlation between both methods.  In addition, the overall eGFR also showed an agreement of both methods. However, the level of eGFRs especially in females were found to be different between both methods with p value of 0.03 in the group with creatinine level < 0.7 mg/dL and p value of 0.02 in the group with creatinine level ≥ 0.7 mg/dL, but no significant difference were found in male with p value of 0.18 in the group with creatinine level < 0.9 mg/dL and p value of 0.23 in the group with creatinine level ≥ 0.9 mg/dL. Conclusion: Taken together, the measurement of creatinine level by enzymatic method and Jaffe kinetic showed a positive correlation and a strong agreement of both methods. However, the differences of eGFRs were still found particularly in female groups. Therefore, caution must be taken when interpreting the eGFRs results that analyzed by difference methods.