Comparing the effect of delayed serum separation on Creatinine measurement by Jaffe and Sarcosine oxidase enzymatic methods with different time and temperature

Abstract

—Creatinine is a nitrogenous organic waste product and increased in serum under abnormal renal function. Commonly used methods for creatinine measurement are Jaffe and Sarcosine Oxidase enzymatic methods. Delays in serum separation may cause changes in serum creatinine level. This could lead to misclassification of the stages of Chronic Kidney Disease. The study was carried out in normal pooled serum to find the changes in the serum creatinine levels of normal individuals, if the blood is stored for different periods and the serum separation is delayed. Ten milliliters (10 mL) of blood from 3 healthy individuals were pooled, equally divided and were stored. Creatinine concentrations in the serum immediately separated from the blood samples which were stored for 2 and 6 hours & 1, 2 & 3 days, at room temperature (≈ 27 − 29◦C) & in a refrigerator were measured. The results indicated that the Sarcosine Oxidase enzymatic method gives more accurate values of serum creatinine level than the Jaffe method. Samples can be stored at room temperature for 6 h without significant change in creatinine concentration (p<0.5) and refrigerator is the best method for delayed serum separation (p<0.5).