Reduction in urea distribution volume over time in clinically stable dialysis patients.
We have previously shown that, assuming urea distribution volume (V) remains constant for 1 month, ionic dialysance (ID) allows the dialysis dose to be calculated without the need for blood sampling. The aim of this multicenter study was to verify whether the assumption of a constant V can be extended to 1 year. In clinically stable patients receiving thrice-weekly hemodialysis at 13 dialysis centers, V and Kt/V were assessed during three dialysis sessions at baseline and 1 year later using ID as dialyzer urea clearance and the single-pool urea kinetic model. Baseline albumin, hemoglobin, and C reactive protein were prespecified covariates for predicting the change in V over time. Of the 52 enrolled patients, 40 (25 males; age 63.0+/-13.5 years) completed the study. Baseline end-dialysis body weight (62.4+/-13.7 kg) showed a non-significant 1% reduction during follow-up (-0.6+/-2.8 kg; P=0.175), whereas V significantly decreased from 29.0+/-6.8 to 27.4+/-6.0 l (-1.6+/-3.0 l or 4.5%; P=0.002). The reduction in V was greater when baseline albumin was lower (P=0.001) and baseline V was higher (P=0.005). The single-pool K(t)/V calculated using baseline V underestimated the actual value by 0.07+/-0.16 (P=0.008). The slight underestimate of Kt/V during follow-up suggests that annual V evaluations may be sufficient for dialysis dose quantification as the only risk is underestimating the actually delivered dialysis dose. However, the relationship between baseline albumin and the reduction in V over time may have nutritional value, and suggests more frequent V evaluations.
Di Filippo
S
S
Department of Nephrology and Dialysis, Ospedale A. Manzoni, Lecco, Italy. s.difilippo@ospedale.lecco.it
Andrulli
S
S
Mangano
S
S
Baragetti
I
I
Masa
A
A
Di Filippo
G
G
Mura
C
C
Nachtigal
J
J
Baruffaldi
M
M
Barbisoni
F
F
Cravero
R
R
Agliata
S
S
Amar
K
K
Faranna
P
P
Locatelli
F
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000419:Albuminuria / Q000652:urine; D001835:Body Weight; D002097:C-Reactive Protein / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007668:Kidney / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009752:Nutritional Status; D011237:Predictive Value of Tests; D011446:Prospective Studies; D006435:Renal Dialysis; D013997:Time Factors; D014508:Urea / Q000652:urine*
D006454:Hemoglobins; D014508:Urea; D002097:C-Reactive Protein