title: Performance of serum cystatin C versus serum creatinine as a marker of glomerular filtration rate as measured by inulin renal clearance.
abstract: BACKGROUND
  Serum cystatin C was recently proposed as an alternative marker of glomerular filtration rate (GFR), with a suggested better performance than creatinine. However, detailed studies are limited. We evaluated the performance of cystatin C as a GFR marker.
  
  
  METHODS
  GFR was measured by inulin clearance in 763 Japanese subjects. Factors other than GFR influencing serum cystatin C or serum creatinine were analyzed by multivariate analyses.
  
  
  RESULTS
  After adjustment for GFR, the value of serum creatinine was 25.2% lower in females than males, and decreased by 5.2% for every 20 years of age. Serum cystatin C was 8.2% lower in females, and did not change significantly with aging. Creatinine but not cystatin C was significantly affected by body weight, height and body mass index after adjustment for GFR, gender and age. The correlation coefficient between GFR and 1/cystatin C was significantly higher than that of 1/creatinine in total subjects (0.866 and 0.810, respectively, p < 0.001). Unlike serum creatinine, serum cystatin C did not increase in association with the reduction of GFR in subjects with very low GFR. The regression line of 1/cystatin C against GFR showed a significantly negative intercept of about -8 ml/min/1.73 m(2).
  
  
  CONCLUSIONS
  The performance of serum cystatin C was not good in the subjects with very low GFR. Non-renal elimination of cystatin C may contribute to the result. The correlation between reciprocal cystatin C and GFR suggested its superiority in predicting GFR compared to creatinine in subjects with normal and mildly reduced GFR.
authors.affiliation: Department of Functional Diagnostic Science, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan. horio@sahs.med.osaka-u.ac.jp
authors.forename: Masaru
authors.initials: M
authors.lastname: Horio
authors.forename: Enyu
authors.initials: E
authors.lastname: Imai
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Yasuda
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Seiichi
authors.initials: S
authors.lastname: Matsuo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007444:Inulin; D007564:Japan; D007668:Kidney / Q000503:physiopathology*; D007674:Kidney Diseases / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D055815:Young Adult
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D007444:Inulin; D003404:Creatinine