The effect of normalization of ECW volume as a marker of hydration in peritoneal dialysis patients and controls.
OBJECTIVE
We measured extraceLlular water (ECW) and intracellular water (ICW) volumes in peritoneal dialysis (PD) patients and controls to determine the effect of ICW variation on ECW/ICW ratio and to compare alternative ratios of ECW to height, height2, weight, and body surface area (BSA).


METHODS
We measured body water compartments by deuterium oxide and bromide dilution in 29 PD patients (14 M, 15 F) and 31 controls (15 M, 16 F).


RESULTS
ECW was similar in PD patients (17.58 +/- 3.58 L) and controls (17.20 +/- 2.97 L), p = NS. ICW was nonsignificantly lowerin PD patients (17.58 +/- 4.88 L) than in controls (19.71 +/- 5.08 L), p = NS. ECW/ICW was greaterin PD patients (1.06 +/- 0.32) than in controls (0.92 +/- 0.25), p = 0.057, and was inversely correlated with ICW in PD patients (r = -0.733, p < 0.0001) and controls (r = -0.721, p < 0.0001). In contrast, ECW/height, ECW/height2, ECW/weight, and ECW/BSA were similar for the two groups.


CONCLUSIONS
ECW/ICW is affected by changes in ICW as well as by ECW varying with hydration. ECW/ICW ratio leads to the spurious impression of overhydration in subjects with smaller ICW volumes. ECW/ICW does not reflect hydration alone and other methods of expressing ECW as a measure of hydration need further evaluation.
Woodrow
Graham
G
Renal Unit, Leeds General Infirmary, United Kingdom. graham.woodrow@leedsth.nhs.uk
Oldroyd
Brian
B
Wright
Antony
A
Coward
W Andrew
WA
Truscott
John G
JG
D000293:Adolescent; D000328:Adult; D001824:Body Constitution; D045604:Extracellular Fluid / Q000502:physiology; D005260:Female; D006801:Humans; D007424:Intracellular Fluid / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D014882:Water-Electrolyte Balance / Q000502:physiology*