title: Evolution and predictive power of serum cystatin C in acute renal failure.
abstract: OBJECTIVE
  The serum concentration of cystatin C has recently been proposed as a better indicator of glomerular filtration rate (GFR) than plasma creatinine. Little is known about cystatin C in critical illness. We assessed serum cystatin C as a marker of renal function in acute renal failure (ARF) and its power in predicting survival of ARF patients.
  
  
  METHODS
  202 consecutive adult patients admitted into the intensive care unit (ICU) during a period of 9 months.
  
  
  METHODS
  Serum cystatin C, plasma creatinine and plasma urea were measured on admission, daily during the first 3 days, and 5-7 times a week during the rest of the ICU stay. The patients with and without ARF were compared by the Mann-Whitney U-test. The correlation between different variables was calculated by Spearman's correlation. Forward stepwise multiple regression analysis was performed to test independent predictors of mortality. The positive predictive value of serum cystatin C and plasma creatinine for ARF and mortality was calculated by ROC analysis.
  
  
  RESULTS
  ARF occurred in 54 patients (27%). Serum cystatin C showed excellent positive predictive value for ARF in critical illness by ROC analysis. In acute renal dysfunction, abnormal values of serum cystatin C and plasma creatinine appeared equally quickly (median 3 days). The diagnosis of ARF, the day 1 Apache II score and admission plasma creatinine appeared as independent predictors of hospital mortality. ROC analysis showed only weak predictive power for serum cystatin C and plasma creatinine regarding hospital mortality.
  
  
  CONCLUSIONS
  Serum cystatin C was as good as plasma creatinine in detecting ARF in intensive care patients. Neither marker was clinically useful in predicting mortality.
authors.affiliation: Department of Surgery, Division of Anesthesiology and Intensive Care Medicine, Intensive Care Unit, Helsinki University Hospital, Helsinki, Finland. annika.ahlstrom@hus.fi
authors.forename: A
authors.initials: A
authors.lastname: Ahlström
authors.forename: M
authors.initials: M
authors.lastname: Tallgren
authors.forename: S
authors.initials: S
authors.lastname: Peltonen
authors.forename: V
authors.initials: V
authors.lastname: Pettilä
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000401:mortality*; D000328:Adult; D000368:Aged; D003404:Creatinine / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015996:Survival Rate; D014508:Urea / Q000097:blood
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D014508:Urea; D003404:Creatinine