Background: Continuous exposure of the peritoneal membrane to dialysis solutions during long-term dialysis results in mesothelial cell loss, peritoneal membrane damage, and thereby, ultrafiltration (UF) failure, a major determinant of mortality in patients on continuous ambulatory peritoneal dialysis (CAPD). Unfortunately, none of tests available today can predict long-term UF decline. Here, we propose a new tool to predict such a change.
Patients and methods: Mesothelial cells from 8-hour overnight effluents (1.36% glucose dialysis solution) were harvested, co-stained with cytokeratin (a mesothelial marker) and TUNEL (an apoptotic marker), and were counted using flow cytometry in 48 patients recently started on CAPD. Adequacy of dialysis, UF, nutrition status, dialysate cancer antigen 125 (CA125), and a peritoneal equilibration test (3.86% glucose peritoneal dialysis solution) were simultaneously assessed and were re-evaluated 1 year later.
Results: The numbers of total and apoptotic mesothelial cells were 0.19 +/- 0.19 million and 0.08 +/- 0.12 million cells per bag, respectively. Both numbers correlated well with the levels of end dialysate-to-initial dialysate (D/D(0)) glucose, dialysate-to-plasma (D/P) creatinine, and sodium dipping. Notably, the counts of cells of both types in patients with diabetes or with high or high-average transport were significantly greater than the equivalent counts in nondiabetic patients or those with low or low-average transport. A cut-off of 0.06 million total mesothelial cells per bag had sensitivity of 1 and a specificity of 0.75 in predicting a further decline in D/D(0) glucose and a sensitivity of 0.86 and a specificity of 0.63 to predict a further decline in UF over a 1-year period. In contrast, dialysate CA125 and other measured parameters had low predictive values.
Conclusions: The greater the loss of exfoliated cells, the worse the expected decline in UF. The ability of a count of mesothelial cells to predict a future decline in UF warrants further investigation in clinical practice.