OBJECTIVE: This study aimed to compare the correlations between KT/V and creatinine clearance (Ccr) calculated by different methods and to determine and compare the correlations between KT/V 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 KT/V 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 KT/V and Ccr. RESULTS: Sixty-three data sets were collected from 52 CAPD patients. The correlations between weekly KT/V 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), KT/V 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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