Abstract
Objective
This study aimed to compare the correlations between KTN and creatinine clearance (Ccr) calculated by different methods and to determine and compare the correlations between KTN and Ccr.
Design
Nonrandomized, retrospective analysis of data.
Setting
Continuous ambulatory peritoneal dialysis (CAPD) outpatient clinic in a teaching hospital.
Patients
All patients were included for analysis if the data collection was complete for the calculations of KTN and Ccr using five different methods.
Interventions
Volume of distribution for urea (V) was estimated by four methods: Watson nomogram, ideal body weight (IBW), actual body weight, and total body surface area. Ccr was determined by five methods: Dialysate Ccr was calculated by creatinine (Cr) uncorrected and corrected for the presence of glucose; urinary Ccr was calculated using urinary Cr alone and the average urinary clearance of urea and Cr; and by the Cockcroft and Gault method.
Main Outcome Measures
Correlations between KTN and Ccr.
Results
Sixty-three data sets were collected from 52 CAPD patients. The correlations between weekly KTN and Ccr normalized to 1.73 m2 body surface area were found to be highly variable from one method to another (r2 = 0.012 -0.494). For obese patients (20% above IBW), KTN values obtained were more variable using the Watson nomogram compared to the IBW and BSA methods.
Conclusion
KT/V calculated using the Watson nomogram and the Ccr determined using average of urinary urea and creatinine clearance gave the best correlation (r2 = 0.49).
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