Estimating glucose absorption in peritoneal dialysis using peritoneal equilibration tests

To determine peritoneal dialysis patients' dietary energy requirements, the glucose absorbed from the dialysate needs to be quantified. The currently accepted method of estimating glucose absorption is based on the average glucose absorption of 7 continuous ambulatory peritoneal dialysis (CAPD) patients (Grodstein, 1981). Peritoneal equilibration test curves have shown that modality and transport characteristics affect glucose absorption. To test a more accurate procedure for estimating glucose absorption, we compared two different methods of determining the actual glucose absorption: Grodstein formula: (11.3 xa-10.9) liters of dialysate, where xa is the average glucose concentration, and the D/D0 formula: (1-D/D0)xi, where xi is the initial glucose instilled, using 4-hour D/D0 for CAPD and dwell time D/D0 for automated peritoneal dialysis (APD). Twenty-four-hour glucose absorption was measured in 50 CAPD patients and 17 APD patients. Absorption was calculated from the glucose remaining in the 24-hour spent dialysate. Wilcoxon sign rank statistical analysis showed the D/D0 formula results to be closer to actual glucose absorbed (CAPD: p = 0.0153; APD: p = 0.0001). The D/D0 formula is individualized for patients' modality and membrane characteristics and easy to calculate from readily available information.