Detection of decreased glomerular filtration rate in intensive care units: serum cystatin C versus serum creatinine

BACKGROUND: Detecting impaired glomerular filtration rate (GFR) is important in intensive care units (ICU) in order to diagnose acute kidney injuries and adjust the dose of renally excreted drugs. Whether serum Cystatin C (SCysC) may better reflect glomerular filtration rate than serum creatinine (SCr) in the context of intensive care medicine is uncertain. METHODS: We compared the performance of SCysC and SCr as biomarkers of GFR in 47 critically ill patients (median SOFA (Sepsis-related Organ Failure Assessment) score of 5) for whom GFR was measured by a reference method (urinary clearance of iohexol). RESULTS: Mean Iohexol clearance averaged 96 ± 54 mL/min and was under 60 mL/min in 28% of patients. Mean SCr and SCysC concentrations were 0.70 ± 0.33 mg/dL and 1.26 ± 0.61 mg/L, respectively. Area under the ROC curve for a GFR threshold of 60 mL/min was 0.799 and 0.942 for SCr and SCysC, respectively (p = 0.014). CONCLUSIONS: We conclude that ScysC significantly outperfoms SCr for the detection of an impaired GFR in critically ill patients. TRIAL REGISTRATION: ClinicalTrials.gov: B7072006347