Serum cystatin C as a better marker of vancomycin clearance than serum creatinine in elderly patients.

Objectives: 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.