Assessment of dialysis dose by measured clearance versus extrapolated data.
OBJECTIVE
To determine whether estimates of daily dialysis clearance of creatinine and urea, based on data from the 4-hour peritoneal equilibration test, correlate well with daily dialysis clearance measured by 24-hour dialysate collection in chronic ambulatory peritoneal dialysis patients.


METHODS
Prospective study in which each subject collected all dialysate from a 24-hour period and then immediately thereafter underwent a standard peritoneal equilibration test (PET). Daily clearances of creatinine and urea were calculated from 24-hour dialysate collections by standard methods and then were compared with several estimates of 24-hour clearance based on PET data.


METHODS
Single peritoneal dialysis unit of a university teaching hospital.


METHODS
Thirty-six stable patients on continuous ambulatory peritoneal dialysis (CAPD).


RESULTS
The estimated values for daily dialysis clearance both overestimated and underestimated the measured 24-hour clearance. The correlation coefficient between the extrapolations and the actual 24-hour clearances ranged from 0.63-0.68. The range of discordance for daily creatinine clearance was from -2530 mL/day to +2199 mL/day. For daily urea clearance, the range of discordance was from -2103 mL/day to +1940 mL/day. The peritoneal membrane transport characteristics of the individual patient did not predict whether the extrapolation overestimated or underestimated the measured daily clearance.


CONCLUSIONS
Extrapolation of PET data is not a reliable method to estimate the dose of dialysis delivered to the patient. A 24-hour collection of dialysis is necessary for this determination.
Burkart
J M
JM
Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina.
Jordan
J R
JR
Rocco
M V
MV
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000378:metabolism*; D015314:Dialysis Solutions / Q000008:administration & dosage / Q000737:chemistry; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010531:Peritoneal Dialysis, Continuous Ambulatory; D011446:Prospective Studies; D014508:Urea / Q000378:metabolism*
D015314:Dialysis Solutions; D014508:Urea; D003404:Creatinine