ABSTRACT
Outcomes for pediatric peritoneal dialysis (PD) patients are closely related to dialysis adequacy and nutrition, which need to be measured frequently using a number of laboratory parameters. Although the critical meaning of adequacy and nutrition in the long-term prognosis of dialyzed children is well-documented, PD prescriptions are still largely empirical. Our objective was to evaluate nutritional and dialytic parameters in PD children (urea, creatinine, and albumin excretion in dialysate and urine, and daily protein intake); to measure peritoneal equilibration test (PET) results, Kt/V, normalized equivalent of protein nitrogen appearance (nPNA) and nitrogen balance; and to study the correlations between those variables. We performed 59 prospective laboratory measurements in 15 stable PD patients (7 boys; mean age: 6.7 years; age range: 1.1-14.8 years) during 6 months of follow-up. Creatinine, urea, total protein, and albumin were measured in plasma, urine, and dialysate. We calculated PET, Kt/V, daily dietary protein intake (DPI), protein catabolic rate (PCR), and nPNA. All statistical comparisons used the paired t-test, and correlations were calculated by two-way analysis of variance for repeated measures. A value of p < 0.05 was considered significant. The mean 4-hour dialysate-to-plasma ratio (D/P) of creatinine was 0.78 +/- 0.02 at month 0 and 0.74 +/- 0.13 at month 6 [p = nonsignificant (NS)]. The mean final-dialysate-to-initial-dialysate ratio (D/D0) of glucose was 0.35 +/- 0.11 and 0.34 +/- 0.08 at the same intervals (p = NS). The D/P creatinine showed an inverse correlation with patient age and body surface area, and the D/D0 glucose ratio showed a positive correlation with both of those parameters (p < 0.05). Weekly total and residual Kt/V urea were 3.41 +/- 0.86 and 1.49 +/- 1 respectively. The daily DPI was 3.32 +/- 1.05 g/kg, and the daily PCR was 1.32 +/- 0.47 g/kg, showing a positive net protein balance (DPI-PCR = +2 g/kg daily), which was negatively correlated with age and body surface area (p < 0.001). The mean daily nPNA was 0.94 +/- 0.33 g/kg, which was negatively correlated with age and body surface area (p < 0.05, r = -0.51), and positively correlated with daily DPI and total and residual Kt/V (p < 0.0001). Our patients could be classified as high-average transporters, with low-average ultrafiltration. The high transport state was associated with greater peritoneal albumin losses, a point of concern at younger ages. Total Kt/V and nPNA were higher for the youngest patients, suggesting a favorable nutrition status, but more studies are needed to determine the best value for both parameters in clinical practice.
