Modification of the Glucose Correction Factor by Peritoneal Dialysis Solution Type in the Peritoneal Equilibration Test

The peritoneal equilibration test (PET) is the most widely used measure of peritoneal membrane transport status in peritoneal dialysis (PD) patients (1). Central to this assessment is measurement of dialysate and plasma creatinine. The Jaffe reaction continues to be the most widely used method of creatinine determination (2,3). The presence of substances such as ascorbate, bili-rubin, cephalosporin antibiotics, and glucose results in interference in the measurement of creatinine by this reaction (4). Using the Jaffe method, Tam et al. con-firmed a positive linear relationship between glucose concentration and spurious creatinine concentrations sampled from unused PD solution of various glucose con-centrations (5). The linear relationship allows for a math-ematical adjustment of a center-specif ic glucose correction factor for dialysate creatinine determination by taking an average of the ratios of the “measured” creatinine concentration and the measured glucose con-centration from samples of unused PD solution of a fixed glucose concentration. Application of the glucose correction factor allows for a more accurate assessment of peritoneal membrane transport characteristics during a routine PET. Further-more, in recent years, the switch from a 2.5 % PET to a modified 4.25 % PET, as suggested by current guidelines to better discriminate and characterize ultrafiltration failure, has the potential to further spuriously elevate peritoneal membrane transport status (dialysate-to-plasma ratio of creatinine higher than it actually is) if the glucose correction factor is not applied (6). Despite increased interest and use of novel, neutral pH, low glucose degradation product (GDP), glucose-based PD solutions, little is known regarding the impact of other constituents of these solutions (including bi-carbonate and a lower GDP content) on the relationship between glucose concentration and the measured creat-inine concentration determined from the Jaffe reaction. Here, we sought to determine whether the glucose cor-rection factor required modification in the presence of a commercially available low GDP, neutral pH, PD solution