Objective: This study describes a modified 4-hour peritoneal equilibration test (PET) for analyzing peritoneal transport characteristics of proteins with different molecular weights and predicting daily peritoneal protein losses in children on chronic peritoneal dialysis (PD).
Design: Cross-sectional study.
Setting: A single regional pediatric dialysis unit in a teaching hospital.
Patients: 9 stable pediatric dialysis patients; 4 were on continuous ambulatory PD, 5 were on continuous cycling PD.
Main outcome measures: Serum and dialysate concentrations of IgG, albumin, beta2-microglobulin, and transferrin were determined during a PET. Changes in dialysate-to-plasma (D/P) ratios were determined hourly. Agreement between PET-derived and measured daily peritoneal protein losses was examined.
Results: The D/P ratio decreased with increased molecular radius (p < 0.0001). Many children had low plasma levels of IgG, albumin, and transferrin, but elevated levels of beta2-microglobulin. The D/P ratio increased linearly during the PET for all measured proteins, regardless of molecular weight. There was close correlation between 4-hour PET protein losses and 24-hour losses during routine PD.
Conclusions: Proteins are lost through the peritoneum according to their size, demonstrating linear transport kinetics during a 4-hour PET. The PET-derived data predicted daily protein losses in children on chronic PD. This approach might help to eliminate inaccuracies due to incomplete dialysate collection.