Toward targets for initiation of chronic dialysis.
OBJECTIVE
To better define the targets for initiation of chronic dialysis, we compared the relationship between the normalized protein equivalent of nitrogen appearance (nPNA, g/kg standard weight/day) and weekly urea clearance (Kt) normalized to total body water (V) in predialysis chronic renal failure (CRF) patients and in patients on continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis (HD). We also studied the relationships of other nutritional parameters to weekly Kt/Vurea in CRF patients.


METHODS
This cross-sectional study was a prospective observational design meant to study each patient once.


METHODS
The University Hospital and Clinics and Harry S. Truman VA Medical Center, Columbia, Missouri.


METHODS
Forty-five consecutive predialysis CRF patients were enrolled and the results compared with patients on CAPD and HD.


RESULTS
In CRF, the nPNA calculated from urea appearance correlated with the weekly Kt/Vurea (r = 0.57, p < 0.0001) and, using exponential best-fit, nPNA = 1.217 x (1-e-0.769Kt/V). This exponential relationship was similar to that for CAPD and both were different from that in patients on HD. Likewise, nPNAs, calculated from Kjeldahl nitrogen output, and weekly Kt/Vurea were correlated (r = 0.37, p = 0.014) and, using exponential best-fit, nPNA = 1.102(1-e-0.867Kt/V), similar to the relationship in patients on CAPD. Evidence is presented that these relationships are not explained only by mathematical coupling. There was a significant correlation between the weekly Kt/Vurea and 24-hour urinary creatinine excretion.


CONCLUSIONS
The findings suggest that in CRF, as in CAPD, a weekly Kt/Vurea less than 2.0 is likely to be associated with a nPNA less than 0.9 g/kg standard weight. In CRF patients, initiation of chronic dialysis should be considered if weekly renal Kt/Vurea falls below 2.0 and a nPNA greater than 0.8 is desired.
Mehrotra
R
R
Department of Internal Medicine, University of Missouri-Columbia 65212, USA.
Saran
R
R
Moore
H L
HL
Prowant
B F
BF
Khanna
R
R
Twardowski
Z J
ZJ
Nolph
K D
KD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000503:physiopathology; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000378:metabolism; D009752:Nutritional Status; D010531:Peritoneal Dialysis, Continuous Ambulatory; D011446:Prospective Studies; D006435:Renal Dialysis; D013997:Time Factors; D014508:Urea / Q000378:metabolism
D014508:Urea; D009584:Nitrogen