title: [Value of creatinine clearance rate estimated based on serum cystatin C in patients with acute kidney injury].
abstract: OBJECTIVE
  To investigate diagnostic value of creatinine clearance rate (CCr) based on serum cystatin C (SCys C) in acute kidney injury (AKI), and whether it could predict the need for renal replacement therapy (RRT).
  
  
  METHODS
  The patients enrolled with the length of intensive care unit (ICU) stay over 3 days were collected from August 2010 to May 2011. According to the diagnosis of AKI during the ICU stay, patients were divided into the AKI group (n=21) and non-AKI group (n=30). After patients were admitted, the level of SCys C and creatinine (SCr) were measured so as to count CCr based on SCys C (SCys C-CCr) or on SCr (SCr-CCr) respectively, meanwhile urine volume and acute physiology and chronic health evaluation II (APACHE II) score were monitored. The value of CCr counted by SCys C and SCr on predict AKI and the correlations between RRT were compared.
  
  
  RESULTS
  SCr-CCr and SCys C-CCr in AKI group both were significantly lower than non-AKI group all the way through on admission, and 2 days and 1 day before AKI diagnosed and the day AKI diagnosed. The level of SCys C-CCr on 2 days prior to AKI diagnosed was significantly lower than the day admitted (70.6±8.4 ml×min(-1)×1.73 m(-2) vs. 114.8±15.8 ml×min(-1)×1.73 m(-2), P<0.01), whereas the level of SCr-CCr were not significantly changed (76.4±19.3 ml×min(-1)×1.73 m(-2) vs. 78.7±22.1 ml×min(-1)×1.73 m(-2), P>0.05). Receptor operative curve (ROC) analysis indicated that SCys C-CCr could predict AKI earlier than SCr-CCr, as the area under curve (AUC) of SCys C-CCr and SCr-CCr on 2 days prior to AKI diagnosed were 0.859 and 0.664, respectively, and the sensitivity were 90.5% and 47.6%, the specificity were 76.2% and 81.0%. In AKI group 6 patients were treated with RRT, the AKI patients receiving RRT had significantly higher APACHE II score on admission (29.6±4.5 vs. 17.0±5.6, P<0.05) and less urine volume within 24 hours (740±465 ml vs. 1780±1230 ml, P<0.05) than patients not received RRT, however, SCys C-CCr has no significant difference between the sub-group (50.4±11.2 ml×min(-1)×1.73 m(-2) vs. 53.0±8.4 ml×min(-1)×1.73 m(-2), P>0.05). SCys C-CCr did not predict the need of RRT on the day to diagnose AKI (AUC=0.65).
  
  
  CONCLUSIONS
  The sensitivity of SCys C-CCr were high, but its specificity not. The SCys C-CCr may be helpful for excluding diagnose of AKI in high risk patients. However, it could not predict the need for renal replacement therapy on the day AKI diagnosed.
authors.affiliation: Department of Critical Care Medicine, the First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi, China.
authors.forename: Jun-Tao
authors.initials: JT
authors.lastname: Hu
authors.forename: Xian-Long
authors.initials: XL
authors.lastname: Xie
authors.forename: Zhan-Hong
authors.initials: ZH
authors.lastname: Tang
authors.forename: Chao-Qian
authors.initials: CQ
authors.lastname: Li
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Zhou
mesh_terms: D018806:APACHE; D058186:Acute Kidney Injury / Q000378:metabolism*; D000328:Adult; D000368:Aged; D003404:Creatinine / Q000378:metabolism*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D017582:Renal Replacement Therapy; D012189:Retrospective Studies
chemical_list: D055316:Cystatin C; D003404:Creatinine