Evaluation of Residual Kidney Function during Once-Weekly Incremental Hemodialysis

Abstract

<b><i>Background:</i></b> The initial once-weekly administration of incremental hemodialysis to patients with residual kidney function (RKF) has recently attracted considerable interest. <b><i>Methods:</i></b> The aim of our study was to assess the performance of a series of different methods in measuring serum urea nitrogen and serum Cr (sCr) RKF in patients on once-weekly hemodialysis (1WHD). Evaluations were carried out by means of 24-h predialysis urine collection (Kr-24H) or 6-day inter-dialysis collection (Kr-IDI) and estimation of glomerular filtration rate based on (KrSUN + KrsCr)/2 for the purpose of identifying a simple reference calculation to be used in assessing RKF in patients on 1WHD dialysis. Ninety-five urine samples were collected from 12 1WHD patients. A solute solver urea and Cr kinetic modeling program was used to calculate residual urea and Cr clearances. Mann-Whitney U test, Pearson’s correlation coefficient (<i>R</i>), and linear determination coefficient (<i>R</i>²) were used for statistical analysis. <b><i>Results:</i></b> 1WHD patients displayed a mean KrSUN-IDI of 4.5 ± 1.2 mL/min, while KrSUN-24H corresponded to 4.1 ± 0.9 mL/min, mean KrsCr-IDI to 9.1 ± 4.0 mL/min, and KrsCr 24H to 8.9 ± 4.2 mL/min, with a high regression between IDI and 24-h clearances (for IDI had <i>R</i>² = 0.9149 and for 24H had <i>R</i>² = 0.9595). A good correlation was also observed between KrSUN-24H and (KrSUN + KrsCR/2) (<i>R</i>² = 0.7466, <i>p</i> &#x3c; 0.01. <b><i>Discussion:</i></b> Urine collection over a 24-h predialysis period yielded similar results for both KrSUN and KrsCr compared to collection over a longer interdialytic interval (KrSUN + KrsCr)/2 could be applied to reliably assess RKF in patients on 1WHD. <b><i>Conclusion:</i></b> The parameters evaluated are suitable for use as a routine daily method indicating the commencement and continued use of the 1WHD Incremental Program.