Differences in peritoneal equilibration test results in patients aged above or below 60 years

Peritoneal permeability, evaluated using the peritoneal equilibration test (PET), indicates that, in an adult population not selected for age, an increase in the transport rate of small solutes usually occurs in the course of peritoneal dialysis (PD) treatment. We evaluated the dialysate-to-plasma ratio of urea (D/P urea), the D/P creatinine, the ratio of dialysate glucose at a designated dwell time to dialysate glucose at 0 dwell time (D/D0 glucose), and the mass transfer-area coefficients (KBDs) of those solutes in PETs performed in patients aged above or below 60 years who were matched for sex, PD duration, and outcome. The single-center, retrospective study was carried out in a peritoneal dialysis unit in a university hospital. Two groups of PD patients were chosen. Mean age of patients in group I (n = 21; 9 women, 12 men) was 67.7 +/- 4.5 years; PD duration was 20.1 +/- 12.1 months. In group II, the patients (n = 21; 9 women, 12 men) had a mean age of 42.8 +/- 9.1 years, and had been treated with PD for 20.7 +/- 12.1 months. A standard PET was performed according to Twardowski et al every 3 months from PD start to PD end. The first results, the mean results representing the entire PD course, and the last results were compared between groups. In addition, the first and the last results were compared within each group. No significant differences were seen between the groups in peritoneal transport in the first PET. In the last PET, the curves for D/P urea and D/P creatinine, and the KBD for urea, were significantly lower in the older patients than the curves obtained at PD start. In consequence, a tendency toward lower D/P ratios or KBDs for urea and creatinine in the last and mean PETs was observed in group I as compared with group II. No significant changes were seen in the peritoneal transfer of glucose in the course of PD or between groups. Older patients may show a reduction in peritoneal permeability from the vascular to the mesothelial side of the membrane in the course of PD treatment; peritoneal transport in the opposite direction remains unchanged during approximately 20 months from the start of PD treatment. The patients under 60 years of age maintain stable bi-directional permeability under a comparable PD duration.