Comparison of Serum Creatinine Measurements among Roche Modular D, Cobas 8000 c702, and Beckman Coulter AU5800, by Jaffe and Enzymatic Methods

0.99, slope: 0.965 and 0.955). When Modular D and Cobas 8000c 702 were compared, the slope and y-intercept were 0.9928 (95% confidence interval [CI]: 0.9802 to 1.000) and -0.0156 (95% CI: −0.0200 to −0.0054), respectively. The slope and y-intercept were 0.9811 (95% CI: 0.9570 to 0.9951) and -0.0484 (95% CI: −0.0638 to −0.0297) when Modular D and Au5800 were compared. Serum Cr measured by Cobas 8000 c702 and AU5800 using the Jaffe method were 3.2% and 6.9% lower than the values measured by Modular D, respectively. Both Modular D and Cobas 8000 c702 showed acceptable accuracies.CONCLUSIONS: Serum Cr measurements using Cobas 8000 c702 and AU5800 were comparable to those measured by Modular D, and showed satisfactory precision and linearity; thus, these techniques could be useful for clinical laboratories.

Creatinine Interference dependent on Glucose and Creatinine Concentrations / 임상검사와정도관리

BACKGROUND: In peritoneal dialysis patients, measurement of creatinine is an important marker of kidney function and gives an information for assessment of dialytic adequacy. High glucose concentration in peritoneal dialysis fluid is known to interfere with creatinine measurement. Creatininine interference with kinetic Jaffe method for glucose and creatinine concentration must be considerated for giving accurate informations about the assessment of dialytic adequacy. METHODS: 10% dextrose fluid (Daihan Pharm Co., Korea) was diluted to prepare specimens with seven different glucose concentrations. Creatinine solutions with seven different concentrations were made with creatinine powder (Sigma-Aldrich Co., USA) and distilled water. The prepared specimens were mixed with equal volume to make total 49 specimens of different glucose and creatinine concentrations. The glucose concentrations of specimens were ranging from 200 mg/dL to 5,000 mg/dL and the creatinine concentrations of specimens were ranging from 0 mg/dL to 10 mg/dL. The specimens were assayed for creatinine with two automated chemistry analysers, Hitachi 7600-110 (Hitachi, Japan) and Unicel DXC 800 (Beckman Coulter Inc., USA). Creatinine HR reagent (Wako Pure Chemical Industries, Japan) and CREA reagent (Roche Diagnostics, Germany) were used in Hitachi 7600-110 analyser, and CREm reagent (Beckman Coulter Inc., Ireland) was used in Unicel DXC 800. RESULTS: Interference of creatinine measurement varied with both glucose and creatinine concentrations to different extent in different analytical systems and reagents. It was observed that creatinine interference increased with increasing glucose concentration in all the systems and reagents. At constant glucose concentration, creatinine interference showd a downward tendency with increasing creatinine concentration among the three reagents. CONCLUSIONS: High glucose concentration and creatinine concentrations provoked the interference of creatinine measurement and the aspect of creatinine interference varied according to the analytic systems and reagents. Each center performing creatinine assay should allow for the creatinine interference and give an accurate results to clinicians.