title: Cystatin C as marker of residual renal function in patients on peritoneal dialysis: relation with parameters of peritoneal function.
abstract: BACKGROUND
  Cystatin C (CysC) is a nonglycosylated protein of low molecular weight not influenced by age, sex or inflammation. The aim of this paper is to ascertain the usefulness of serum CysC level determination in peritoneal dialysis (PD) patients.
  
  
  METHODS
  CysC serum levels were determined in 80 PD patients. The mean age of patients was 53.7 +/- 15 years, with 15.3 +/- 25.8 months on PD. Thirty-three percent were on continuous ambulatory peritoneal dialysis (CAPD) and 66.3% on automated peritoneal dialysis (APD). Fourteen patients (17%) had no residual renal function (RRF).
  
  
  RESULTS
  Mean CysC levels were 5.8 +/- 1.4 mg/L, without differences between men (5.5 +/- 1.4 mg/L) and women (5.6 +/- 1.5 mg/L, NS). There was no correlation between CysC levels and age, weight, height or time on PD. Anuric patients had CysC levels significantly higher than non-anuric (6.7 +/- 1.4 vs. 5.3 +/- 1.3 mg/L, p<0.001). CysC levels showed an inverse correlation with RRF (r=-0.60, p<0.001) and residual urine volume (r=-0.58, p<0.001).
  
  
  CONCLUSIONS
  In conclusion, serum CysC levels had the same statistical significance as plasma creatinine levels, and they are not influenced by peritoneal transport in PD patients. Consequently, both parameters are valid RRF markers.
authors: Nephrology and Biochemistry Unit, University Hospital La Paz, Madrid, Spain. silviarr@universia.es
authors: Silvia
authors: S
authors: Ros
authors: Auxiliadora
authors: A
authors: Bajo
authors: Gloria
authors: G
authors: del Peso
authors: Auxiliadora
authors: A
authors: Garcia de Miguel
authors: Soledad
authors: S
authors: Santacruz
authors: Ernesto
authors: E
authors: Fernandez
authors: Raquel
authors: R
authors: de Garcia
authors: Rafael
authors: R
authors: Selgas
mesh_terms: D000368:Aged; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D051437:Renal Insufficiency / Q000175:diagnosis* / Q000503:physiopathology*
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins