NDT Advance Access published online on July 1, 2009
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfp319
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Categorization of sodium sieving by 2.27% and 3.86% peritoneal equilibration tests—a comparative analysis in the clinical setting
1 Division of Nephrology, Complejo Hospitalario Universitario de A Coruña 2 Department of Medicine, Health Sciences Institute, University of A Coruña, Spain
Correspondence and offprint requests to: Ana Marta Gomes; E-mail: ampgomes{at}gmail.com
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Abstract |
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Background. Analysis of the dialysate sodium concentration during a peritoneal equilibration test (PET) provides information on the rates of water and solute transport through different membrane pathways. A hypertonic (3.86%) glucose-based dialysate may enhance the accuracy of analysis. There are still gaps in our knowledge regarding this question, in the clinical setting.
Objective. The aim of this study was to compare the categorization of the sodium sieving effect in peritoneal dialysis (PD) patients by 2.27% and 3.86% PETs, and to disclose clinical correlates of this phenomenon.
Method. Ninety PD patients underwent prospectively 2.27% and 3.86% modified (dialysate samples at 0, 60, 90, 120 and 240 min) PETs, in a random order. We searched for differences in the time profiles of sodium sieving and its categorization. We correlated sodium sieving with ultrafiltration (UF) and solute transport capacity, as also with selected clinical and demographic variables, using a multivariate approach.
Results. The maximum dip in the dialysate sodium concentration (11.1 mM/L, 3.86% versus 7.1 mM/L, 2.27%, P < 0.001) was most common after 90 min in the 3.86% PET, with the 2.27% test somewhere between 60 and 90 min. Low sodium sieving (defined by a dip <5 mM/L at 60 min) was observed in 8.9% of the patients in the 3.86% test. The same limit categorized 34.4% of the patients as low sieving in the 2.27% test (100.0% sensitivity and 72.0% specificity, using 3.86% as a reference). UF and D/P240 min creatinine were independent predictors of the sodium sieving effect in both tests. Moreover, multivariate analysis disclosed a consistent inverse correlation between GFR and sodium sieving in both the 2.27% (B = –0.23, 95% CI –0.40, –0.07, P = 0.006) and 3.86% PET (B = –0.46, 95% CI –0.65, –0.26, P < 0.0005).
Conclusions. The standard 2.27% PET permits some categorization of sodium sieving in PD patients. However, the information provided by this test lacks the discriminatory capacity of the 3.86% PET, which should be considered the one for reference for this purpose. GFR keeps a consistent inverse correlation with the intensity of sodium sieving in both the 2.27% and 3.86% PET.
Keywords: peritoneal equilibration test; residual renal function; sodium sieving; ultrafiltration
Received for publication: 22.12.08
Accepted in revised form: 5. 6.09