title: Serum cystatin C as a better marker of vancomycin clearance than serum creatinine in elderly patients.
abstract: OBJECTIVE
  The purpose of this study is to assess the usefulness of the concentration of cystatin C (Cys-C) in serum for predicting the clearance of vancomycin (CLvcm) compared with the serum concentration of creatinine (SCr) in the elderly.
  
  
  METHODS
  Thirty-nine serum samples were obtained from 24 elderly patients (65 years and older). Creatinine clearance (CLcr) and the glomerular filtration rate calculated from the concentration of Cys-C (GFRcys-c) were estimated using Cockcroft & Gault's formula and Larsson's formula, respectively.
  
  
  RESULTS
  The correlation constant for CLvcm and the reciprocal of Cys-C (p=0.883) was significantly higher than that for CLvcm and the reciprocal of SCr (p=0.575, p<0.005). GFRcys-c was strongly correlated with CLvcm (p=0.883) and the constant was significantly higher than that for the correlation between CLvcm and CLcr (p=0.684, p<0.05). These results suggest that the serum concentration of Cys-C is a more reliable marker for predicting CLvcm than is SCr in elderly patients.
authors.affiliation: Department of Clinical Pharmaceutics and Pharmacy Practice, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Okamoto
authors.forename: Tatsuichiro
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Midori
authors.initials: M
authors.lastname: Kimura
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ukishima
authors.forename: Akihiro
authors.initials: A
authors.lastname: Sonoda
authors.forename: Noriko
authors.initials: N
authors.lastname: Mori
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kato
authors.forename: Toshio
authors.initials: T
authors.lastname: Maeda
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kagawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics; D015415:Biomarkers / Q000097:blood*; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008657:Metabolic Clearance Rate; D014640:Vancomycin / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D000900:Anti-Bacterial Agents; D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D014640:Vancomycin; D003404:Creatinine