Protein Clearance and Icodextrin

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Objective To analyze the peritoneal transport of serum proteins during continuous ambulatory peritoneal dialysis (CAPD) with icodextrin. Design A comparison was made between CAPD with glucose-based dialysate and, in the same patients, 4 weeks after the instillation of icodextrin for the long night dwell, with icodextrin-based dialysate. Patients Ten stable CAPD patients, who participated in a large randomized multicenter study comparing icodextrin with glucose-based dialysate. Five patients used glucose 1.5% dialysate for the night dwell before its replacement by icodextrin (good ultrafiltration group), and 5 used glucose 4.25% (poor ultrafiltration group). Results The clearance of β2-microglobulin increased by 28% on icodextrin, due to increased convective transport. The clearances of the larger proteins -albumin, IgG, fibronectin, and α2-macroglobulin -remained unaltered, indicating transport of these proteins across the large pore system. The patients with poor ultrafiltration had a higher β2-microglobulin clearance on glucosebased dialysate than the high ultrafiltration group. This indicates that the ultrafiltration failure was caused by a large effective peritoneal surface area, leading to a rapid absorption of glucose. Icodextrin produced significantly more ultrafiltration in the poor ultrafiltration patients than in the high ultrafiltration group. A correlation was found for the β2-microglobulin clearance on glucose-based dialysate and the ultrafiltration produced by icodextrin. Conclusions Icodextrin causes ultrafiltration through the small pore system, whereas glucose-based dialysate has its effect on transcellular water transport. Therefore, the use of icodextrin causes an increased clearance of β2 microglobulin, but not of larger proteins. Icodextrin was especially useful in patients with a large effective surface area leading to ultrafiltration failure during treatment with glucose-based dialysate.