PLASMA IOHEXOL CLEARANCE IN AUTOMATED PERITONEAL-DIALYSIS - ITS ROLE IN ADEQUACY DETERMINATION

Objectives To compare the relationship of-plasma iohexol clearance to standard adequacy measures in an automated peritoneal dialysis (APD) p opulation. Design: Prospective, nonrandomized, open label, simultaneou s clearance studies of novel (iohexol) and traditional (urea and creat inine) markers of dialysis quantitation. Setting: Outpatient peritonea l dialysis units associated with tertiary care university hospitals. P atients: Eighteen stable patients, 13 undergoing continuous cycling pe ritoneal dialysis (CCPD) and 5 receiving intermittent dialysis, who un derwent 24-hour clearance studies were enrolled in and completed the s tudy. Interventions: Each subject received 15 mL of iohexol intravenou sly the morning of a scheduled dialysis night. Blood was obtained for determination of serum concentrations of urea nitrogen and creatinine, and plasma iohexol concentration. Dialysate and urine were collected over 24 hours. Main Outcome Measures: Urea and creatinine data from th e total pooled dialysate and from the 24-hour urine collection were us ed to calculate daily Kt/V-urea and normalized total daily creatinine clearance (CrCl). Total plasma iohexol clearance was calculated using a one-compartment model with the Brochner-Mortensen correction. Result s: Normalized [to 1.73 m(2) body surface area (BSA)] iohexol clearance correlated very well with normalized CrCl (r(2) = 0.777; p < 0.001). A weaker correlation was observed between Kt/V-urea and normalized ioh exol clearance (r(2) = 0.213; 0.05 < p < 0.1). When data are not norma lized using BSA or urea distribution volume, the regressions are impro ved for both creatinine (r(2) = 0.820) and urea (r(2) = 0.533). These results were comparable between those on CCPD and those on intermitten t therapy. Conclusion: Total plasma iohexol clearance provides a simpl e assessment for APD adequacy by eliminating collection problems inher ent to the methodologies currently employed. Such simplicity allows fo r more frequent assessments of delivered dialysis dose and efficacy of prescription changes.