Cystatin C as marker of residual renal function in patients on peritoneal dialysis: relation with parameters of peritoneal function.
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.
Ros
Silvia
S
Nephrology and Biochemistry Unit, University Hospital La Paz, Madrid, Spain. silviarr@universia.es
Bajo
Auxiliadora
A
del Peso
Gloria
G
Garcia de Miguel
Auxiliadora
A
Santacruz
Soledad
S
Fernandez
Ernesto
E
de Garcia
Raquel
R
Selgas
Rafael
R
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*
C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins