Relationship of serum cystatin C to peritoneal and renal clearance measures in peritoneal dialysis: a cross-sectional study

Am J Kidney Dis. 2008 Feb;51(2):278-84. doi: 10.1053/j.ajkd.2007.08.018.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Ascitic Fluid / metabolism*
  • Biomarkers / metabolism
  • Cohort Studies
  • Creatinine / metabolism*
  • Creatinine / urine
  • Cross-Sectional Studies
  • Cystatin C
  • Cystatins / blood*
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Kidney / metabolism*
  • Linear Models
  • Male
  • Middle Aged
  • Peritoneal Dialysis*
  • Predictive Value of Tests
  • Research Design
  • Urea / metabolism*
  • Urea / urine


  • Biomarkers
  • CST3 protein, human
  • Cystatin C
  • Cystatins
  • Urea
  • Creatinine