Journal Article

Estimating total urea removal and protein catabolic rate by monitoring UV absorbance in spent dialysate

Fredrik Uhlin, Ivo Fridolin, Lars-Göran Lindberg and Martin Magnusson

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 20, issue 11, pages 2458-2464
Published in print November 2005 | ISSN: 0931-0509
Published online August 2005 | e-ISSN: 1460-2385 | DOI:
Estimating total urea removal and protein catabolic rate by monitoring UV absorbance in spent dialysate

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Background. Dialysate-based, on-line measurements of Kt/V and protein catabolic rate (PCR) in dialysis patients have been considered more accurate compared with measurements on the blood side during dialysis. The primary aim of this study was to compare total removed urea (TRU) and PCR, normalized to body weight (nPCRw), obtained by three dialysate-based methods: (i) on-line ultraviolet (UV) absorbance of the spent dialysate; (ii) total dialysate collection (TDC), as reference method; and (iii) Urea Monitor 1000 (UM) from Baxter Healthcare Corp.

Methods. We studied 10 uraemic patients on chronic, thrice-weekly haemodialysis. We made absorption measurements (UV radiation) on-line with a spectrophotometer connected to the fluid outlet of the dialysis machine, with all spent dialysate passing through an optical cuvette for single-wavelength measurements. UV absorbance measurements were compared with TDC and the UM.

Results. nPCRw obtained with UV absorbance was 0.82±0.17, that from TDC 0.81±0.18, and that measured by UM 0.87±0.18, which was significantly higher than the results of the other methods. The difference between nPCRw calculated by TDC and by UM was −0.05±0.06, showing a slightly lower SD than the difference between nPCRw by TDC and UV absorbance, −0.01±0.07.

Conclusion. The study demonstrates that TRU, and consequently PCR, can be estimated by on-line measurement of the UV absorption in the spent dialysate.

Keywords: dialysis adequacy; haemodialysis monitoring; protein catabolic rate; total removed urea; urea; UV absorption

Journal Article.  3867 words.  Illustrated.

Subjects: Nephrology

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