OBJECTIVE: To evaluate the influence of glucose and creatinine concentrations on the determination of creatinine by Jaffe picrate reaction and specific enzymatic assay. MATERIAL AND METHOD: Unused dialysate with 4.25% dextrose was diluted to obtain seven glucose concentrations. Two series of dialysate were spiked with creatinine to yield concentrations of 5 and 10 mg/dl. Creatinine measurements were obtained by Jaffe method and enzymatic assay. RESULTS: In unused dialysate solution with glucose concentrations from 559 to 4,250 mg/dl, the creatinine values obtained by the Jaffe method were higher than the enzymatic assay (0.31 +/- 0.20 vs. 0.08 +/- 0.01 mg/dl, p < 0.05). The correlation coefficient between glucose and creatinine from the Jaffe method were 0.98 (p < 0.001) but showed no correlation with creatinine measured with the enzymatic assay. On the other hand, the mean values of creatinine in dialysate with creatinine concentrations of 5 and 10 mg/dl derived by Jaffe method were lower than enzymatic assay (5.74 +/- 0.12 vs. 6.16 +/- 0.36 mg/ dl and 11.56 +/- 0.17 vs. 12.69 +/- 0.66 mg/dl, respectively). At creatinine concentration of 10 mg/dl, the correlation between glucose concentration and creatinine from enzymatic assay was significant. In contrast, at creatinine concentration of 5 mg/ dl, the correlations obtained from both methods were significant. CONCLUSION: The patterns of glucose interference with creatinine obtained from Jaffe method and enzymatic assay were quite different. The magnitude of interference with enzymatic assay was greater at a higher creatinine concentration. Therefore, the enzymatic assay might not be appropriate for creatinine measurement in patients using dialysate with dextrose 4.25% and membrane characteristic of high solute transporter.
OBJECTIVE: To evaluate the influence of glucose and creatinine concentrations on the determination of creatinine by Jaffe picrate reaction and specific enzymatic assay. MATERIAL AND METHOD: Unused dialysate with 4.25% dextrose was diluted to obtain seven glucose concentrations. Two series of dialysate were spiked with creatinine to yield concentrations of 5 and 10 mg/dl. Creatinine measurements were obtained by Jaffe method and enzymatic assay. RESULTS: In unused dialysate solution with glucose concentrations from 559 to 4,250 mg/dl, the creatinine values obtained by the Jaffe method were higher than the enzymatic assay (0.31 +/- 0.20 vs. 0.08 +/- 0.01 mg/dl, p < 0.05). The correlation coefficient between glucose and creatinine from the Jaffe method were 0.98 (p < 0.001) but showed no correlation with creatinine measured with the enzymatic assay. On the other hand, the mean values of creatinine in dialysate with creatinine concentrations of 5 and 10 mg/dl derived by Jaffe method were lower than enzymatic assay (5.74 +/- 0.12 vs. 6.16 +/- 0.36 mg/ dl and 11.56 +/- 0.17 vs. 12.69 +/- 0.66 mg/dl, respectively). At creatinine concentration of 10 mg/dl, the correlation between glucose concentration and creatinine from enzymatic assay was significant. In contrast, at creatinine concentration of 5 mg/ dl, the correlations obtained from both methods were significant. CONCLUSION: The patterns of glucose interference with creatinine obtained from Jaffe method and enzymatic assay were quite different. The magnitude of interference with enzymatic assay was greater at a higher creatinine concentration. Therefore, the enzymatic assay might not be appropriate for creatinine measurement in patients using dialysate with dextrose 4.25% and membrane characteristic of high solute transporter.