Fluid status in CAPD patients is related to peritoneal transport and residual renal function: evidence from a longitudinal study.
BACKGROUND
Both peritoneal transport characteristics as well as residual renal function are related to outcome in patients treated with continuous ambulatory peritoneal dialysis (CAPD). It has been suggested that part of this relationship might be explained by an effect of both parameters on the fluid state in CAPD patients or by the relationship between inflammation and peritoneal transport.


METHODS
In the present study, the relationship between fluid state [extracellular water (ECW) (sodium bromide); total body water (TBW) (deuterium oxide)] with peritoneal transport characteristics (2.27% glucose dialysate/plasma creatinine [D/P (creat)] ratio), residual renal function (residual glomerular filtration rate [rGFR] by urine collection) and C-reactive protein (CRP) was assessed in 37 CAPD patients in a cross-sectional and longitudinal design, with 25 patients completing the study.


RESULTS
In the cross-sectional part ECW, corrected for height (ECW:height), was inversely related to rGFR (r=-0.40, P=0.016), whereas during the longitudinal part, D/P[creat] was related to the change in ECW (r=0.40, P=0.05). Neither D/P[creat] nor rGFR were related to CRP, whereas a significant relationship was observed between ECW:height and CRP (r=0.58, P=0.0001). Patients were dichotomized according to rGFR (<2 or >2 ml/min). Despite a higher daily peritoneal glucose prescription (216.3+/-60.0 vs 156.5+/-53.0 g/24 h; P=0.004) and peritoneal ultrafiltration volume (1856+/-644 vs 658+/-781 ml/24 h, respectively; P=0.0001), the patients with a rGFR <2 ml/min showed a higher ECW:height compared with the group with rGFR >2 ml/min (12.5+/-3.8 vs 9.2+/-2.2 l/m, respectively; P=0.003). Results for TBW were comparable.


CONCLUSIONS
Fluid state was significantly related to peritoneal transport characteristics and rGFR. The larger ECW:height in CAPD patients with a negligible rGFR existed despite a higher peritoneal ultrafiltration volume and higher peritoneal glucose prescription. These findings raise doubts as to whether fluid state in CAPD patients with a diminished rGFR can be adequately controlled on standard glucose solutions without an additional sodium and fluid restriction. The preliminary finding of a relationship between CRP and fluid state might suggest a relationship between overhydration and inflammation.
Konings
Constantijn J A M
CJ
Department of Internal Medicine and Nephrology, Academical Hospital Maastricht, The Netherlands.
Kooman
Jeroen P
JP
Schonck
Marc
M
Struijk
Dick G
DG
Gladziwa
Ulrich
U
Hoorntje
Steven J
SJ
van der Wall Bake
A Warmold
AW
van der Sande
Frank M
FM
Leunissen
Karel M L
KM
D001692:Biological Transport; D001834:Body Water; D001835:Body Weight; D003430:Cross-Sectional Studies; D015314:Dialysis Solutions / Q000493:pharmacokinetics*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000401:mortality / Q000628:therapy; D007677:Kidney Function Tests; D008137:Longitudinal Studies; D008297:Male; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D010539:Permeability; D011336:Probability; D011379:Prognosis; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D016019:Survival Analysis; D016896:Treatment Outcome; D014883:Water-Electrolyte Imbalance / Q000175:diagnosis* / Q000209:etiology
D015314:Dialysis Solutions