title: Calprotectin and neutrophil gelatinase-associated lipocalin in the differentiation of pre-renal and intrinsic acute kidney injury.
abstract: BACKGROUND
  Urinary calprotectin has recently been identified as a promising biomarker for the differentiation of pre-renal and intrinsic acute kidney injury (AKI). This study compares the diagnostic performance of calprotectin and neutrophil gelatinase-associated lipocalin (NGAL) in this differential diagnosis.
  
  
  METHODS
  Urinary calprotectin and NGAL concentrations were assessed in a study population of 87 subjects including 38 cases of intrinsic AKI, 24 cases of pre-renal AKI and 25 healthy controls. Urinary tract obstruction, renal transplantation and metastatic cancer were defined as exclusion criteria.
  
  
  RESULTS
  Mean calprotectin concentrations were significantly lower in pre-renal (190.2 ± 205.7 ng mL(-1) ) than in intrinsic AKI (6250.1 ± 7167.2 ng mL(-1) , P < 0.001). Receiver-operating characteristic (ROC) analysis provided an AUC of 0.99. Mean NGAL concentrations were significantly higher in intrinsic than in pre-renal AKI as well (458.1 ± 695.3 vs. 64.8 ± 62.1 ng mL(-1) , P = 0.001) providing an AUC of 0.82. A combination of the present study population with the cohort of the proof of concept study led to a population of 188 subjects (58 pre-renal AKI, 90 intrinsic AKI, 40 healthy controls). ROC analyses provided an AUC of 0.97 for calprotectin and 0.76 for NGAL yielding sensitivity and specificity values of 93.3 and 94.8% (calprotectin) vs. 75.3 and 72.4% (NGAL). Optimal cut-off values were 440 ng mL(-1) (calprotectin) and 52 ng mL(-1) (NGAL). Pyuria increased calprotectin concentrations independent of renal failure.
  
  
  CONCLUSIONS
  This study shows that both calprotectin and NGAL are able to differentiate between pre-renal and intrinsic AKI after exclusion of pyuria. In the present population, calprotectin presents a higher sensitivity and specificity than NGAL.
authors: Department of Nephrology, Charité - Campus Benjamin Franklin, Berlin, Germany.
authors: F S
authors: FS
authors: Seibert
authors: N
authors: N
authors: Pagonas
authors: R
authors: R
authors: Arndt
authors: F
authors: F
authors: Heller
authors: D
authors: D
authors: Dragun
authors: P
authors: P
authors: Persson
authors: K
authors: K
authors: Schmidt-Ott
authors: W
authors: W
authors: Zidek
authors: T H
authors: TH
authors: Westhoff
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis* / Q000473:pathology / Q000652:urine*; D000209:Acute-Phase Proteins / Q000652:urine*; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D015415:Biomarkers / Q000652:urine; D001706:Biopsy; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007668:Kidney / Q000378:metabolism* / Q000473:pathology; D039841:Leukocyte L1 Antigen Complex / Q000652:urine*; D000071068:Lipocalin-2; D054834:Lipocalins / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011518:Proto-Oncogene Proteins / Q000652:urine*; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; C489506:LCN2 protein, human; D039841:Leukocyte L1 Antigen Complex; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins