Ultrafiltration and small solute transport at initiation of PD: questioning the paradigm of peritoneal function.
BACKGROUND
Human peritoneal function on commencing peritoneal dialysis (PD) is not yet adequately understood. The objective of this study was to determine peritoneal functional patterns on commencing PD.


METHODS
367 end-stage renal disease (ESRD) patients on PD for the first time were studied between their initial second to sixth weeks on PD. Urea and creatinine mass transfer area coefficients (MTAC) and standardized ultrafiltration (UF) capacity were determined.


RESULTS
Mean parametric values were MTAC urea 22.9 +/- 7.04 mL/min, MTAC creatinine 10.31 +/- 4.68 mL/min, and UF 896 +/- 344 mL. Gender, patient size, and diabetes or kidney disease did not affect these parameters. The relationship between values of MTAC creatinine and UF reached statistical significance, although with a low value for Pearson's coefficient (r = -0.30, p = 0.001). Age showed a significant inverse linear correlation with UF capacity (r = -0.15, p = 0.003) and MTAC urea (r = -0.11, p < 0.05). Logistic regression analysis demonstrated that UF below 400 mL was independently related to a high MTAC creatinine and older age. Diabetes was least frequent in patients with the lowest UF. However, in the analysis of MTAC creatinine quintiles, UF values did not follow the expected inverse pattern. The lack of differences in UF between the second and third to fourth MTAC creatinine quintiles is remarkable; MTAC creatinine ranged from 6.71 to 13.54.


CONCLUSIONS
The functional characteristics of human peritoneum varied markedly and there was a less intense than expected relationship between solute and water transports. This mild inverse relationship is intriguing and suggestive of the necessity of redefining some basic concepts. Age was associated with a lower peritoneal UF capacity, in part independently of small solute transport.
Selgas
Rafael
R
Servicio de Nefrología, Hospital Universitario La Princesa, Madrid, Spain. rselgas.hlpr@salud.madrid.org
Bajo
M Auxiliadora
MA
Cirugeda
Antonio
A
del Peso
Gloria
G
Valdés
Jorge
J
Castro
M José
MJ
Sánchez
Sonia
S
Fernández-Reyes
M José
MJ
Hevia
Covadonga
C
Gil
Fernando
F
Aguilera
Abelardo
A
Ortiz
Javier
J
Alegre
Laura
L
Alvarez
Vicente
V
Sánchez-Tomero
J Antonio
JA
D000328:Adult; D000368:Aged; D001692:Biological Transport; D003404:Creatinine / Q000378:metabolism; D015314:Dialysis Solutions / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000378:metabolism*; D012189:Retrospective Studies; D014462:Ultrafiltration; D014508:Urea / Q000378:metabolism
D015314:Dialysis Solutions; D014508:Urea; D003404:Creatinine