Low serum albumin in elderly continuous ambulatory peritoneal dialysis patients is attributable to high permeability of peritoneum.

Our study was carried out to investigate changes in nutrition and individual peritoneal membrane transport characteristics in elderly patients on continuous ambulatory peritoneal dialysis (CAPD), expressed as the personal dialysis capacity (PDC). We performed 376 PDC tests in 229 non diabetic patients who were undergoing CAPD from May 1995 to May 1999 in a multicenter study in Japan. We divided the patients into three groups: elderly (age > or = 65 years, n = 56), middle-aged (age 50-65 years, n = 150), and young (age < 50, n = 170). No significant differences were seen in duration of CAPD and incidence of peritonitis between the groups. We then compared the peritoneal function calculated by PDC test in the groups. Serum levels of albumin in elderly patients were significantly lower than those in middle-aged and young patients (elderly: 3.2 +/- 0.1; middle-aged: 3.4 +/- 0.1, p = 0.0447 vs elderly; young: 3.4 +/- 0.1, p = 0.0272 vs elderly). Plasma protein loss from the peritoneum in elderly patients was significantly higher than in middle-aged and young patients (elderly: 0.11 +/- 0.01; middle-aged: 0.09 +/- 0.01, p = 0.0136 vs elderly; young: 0.09 +/- 0.01, p = 0.0161 vs elderly). No significant differences in ultrafiltration volume and water permeability were seen between the groups. Peritoneal area in the elderly group was significantly higher than in the middle-aged and young groups. Peritoneal creatinine clearance (CCr) and Kt/V in elderly patients were significantly higher than in middle-aged and young patients. However, no significant difference in protein nitrogen appearance (PNA) or protein catabolic rate (PCR) was seen between the groups. Urea and creatinine generation rates in elderly patients were significantly lower than in the middle-aged and young patients. These data show that elderly patients receiving CAPD are well maintained from the perspective of urea and water metabolism, indicating that CAPD therapy for the elderly is more acceptable than expected. However, caution should be exercised, owing to the lower serum albumin seen in elderly patients.