Peritoneal protein losses in children with steroid-resistant nephrotic syndrome on continuous-cycler peritoneal dialysis

Glomerular protein permeability rises in nephrotic syndrome and may result from the effect of an unidentified "circulating factor." The effect of this "circulating factor" on the permeability of other body membranes is unknown. In this study we examine the peritoneal membrane protein permeability in patients with nephrotic syndrome on chronic-cycler peritoneal dialysis. We conducted a retrospective study of peritoneal protein losses in the dialysate effluent of 60 pediatric peritoneal dialysis patients (ages 5.1-22 years) over a 6-year period (January 1997-December 2002). Nineteen patients had steroid-resistant nephrotic syndrome (SRNS), while 41 had other non-nephrotic etiologies of renal failure. Total and normalized peritoneal protein losses are higher in SRNS than in non-nephrotic patients (12,603±5,403 mg/day vs 4,475±469 mg/day, P<0.05; 297.8±79.3 mg/kg per day vs 156.8±16.0 mg/kg per day, P<0.05; 9,614.6±3,253.4 mg/ m² per day vs 4,168.3±367.3 mg/m² per day, P<0.05). The ratio of total protein in dialysate to plasma, a measure of peritoneal membrane protein permeability, was higher in SRNS patients (3.50±1.00% vs 0.68±0.06%, P<0.001). Serum albumin concentration was lower in SRNS patients (3.09±0.13 mg/dl vs 3.52±0.07 mg/dl, P<0.01). There were no differences between the two groups with regard to duration of peritoneal dialysis, dialysis prescription, numbers of peritonitis episodes, catheter replacements, or hospitalizations. In summary, these results demonstrate that peritoneal protein losses in patients with SRNS are twice as great as in those without nephrotic syndrome. These results are consistent with the systemic effect of a "circulating factor" in SRNS and underscore the importance of adequate protein intake in patients on peritoneal dialysis.