| Abstrakt: |
BACKGROUND: Clinical management of peritoneal dialysis patients includes assessments of peritoneal and renal clearances of the low-molecular-weight endogenous solutes creatinine and urea. Cystatin C is a low-molecular-weight protein used as a glomerular filtration rate marker. We investigated whether serum cystatin C concentration is related to peritoneal and renal clearances of creatinine and urea. STUDY DESIGN: Cross-sectional study. SETTING & PARTICIPANTS: 119 patients undergoing peritoneal dialysis in a single dialysis unit. PREDICTOR: Peritoneal, renal, and total clearance of urea as Kt/V(urea) and creatinine as weekly creatinine clearance (C(Cr)). Residual renal function (RRF) as the average of renal clearances of urea and creatinine. OUTCOMES & MEASUREMENTS: Serum concentrations of cystatin C measured by using a particle-enhanced nephelometric immunoassay. RESULTS: Serum cystatin C concentration was related inversely to RRF (Spearman rank correlation coefficient [r(s)] = -0.65; P < 0.001), total weekly C(Cr) (r(s) = -0.52; P < 0.001), and total Kt/V(urea) (r(s) = -0.23; P = 0.01). In a multiple regression model, weight, normalized protein catabolic rate, and RRF had independent effects on serum cystatin C concentrations. Additional multiple regression models showed that only the renal components of Kt/V(urea) and weekly C(Cr) contributed to serum cystatin C concentrations. LIMITATIONS: Absence of reference GFR method. CONCLUSIONS: Serum cystatin C concentrations reflect predominantly renal, not peritoneal, clearance. Serum cystatin C measurement may be a simple and practical alternative to measurement of RRF. Copyright © 2008 National Kidney Foundation, Inc. [ABSTRACT FROM AUTHOR] |
