title: Prognostic value of tubular proteinuria and enzymuria in nonoliguric acute tubular necrosis.
abstract: BACKGROUND
  Acute tubular necrosis (ATN) has high mortality, especially in patients who require renal replacement therapy (RRT). We prospectively studied the diagnostic accuracy of the urinary excretion of low-molecular-weight proteins and enzymes as predictors of a need for RRT in ATN.
  
  
  METHODS
  In 73 consecutive patients with initially nonoliguric ATN, we measured urinary excretion of alpha(1)- and beta(2)-microglobulin, cystatin C, retinol-binding protein, alpha-glutathione S-transferase, gamma-glutamyltransferase, lactate dehydrogenase, and N-acetyl-beta-D-glucosaminidase early in the course of ATN.
  
  
  RESULTS
  Twenty-six patients (36%) required RRT a median of 4 (interquartile range, 2-6) days after detection of proteinuria and enzymuria. Patients who required RRT had higher urinary cystatin C and alpha(1)-microglobulin [median (interquartile range), 1.7 (1.2-4.1) and 34.5 (26.6-45.1) g/mol of creatinine] than patients who did not require RRT [0.1 (0.02-0.5) and 8.0 (5.0-17.5) g/mol of creatinine]. Urinary excretion of cystatin C and alpha(1)-microglobulin had the highest diagnostic accuracies in identifying patients requiring RRT as indicated by the largest areas under the ROC curves: 0.92 (95% confidence interval, 0.86-0.96) and 0.86 (0.78-0.92), respectively. Sensitivity and specificity were 92% (95% confidence interval, 83-96%) and 83% (73-90%), respectively, for urinary cystatin C >1 g/mol of creatinine, and 88% (78-93%) and 81% (70-88%) for urinary alpha(1)-microglobulin >20 g/mol of creatinine.
  
  
  CONCLUSIONS
  In nonoliguric ATN, increased urinary excretion of cystatin C and alpha(1)-microglobulin may predict an unfavorable outcome, as reflected by the requirement for RRT.
authors.affiliation: Department of Nephrology, University Hospital, Essen, Germany. stefan.herget-rosenthal@uni-essen.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Herget-Rosenthal
authors.forename: Dennis
authors.initials: D
authors.lastname: Poppen
authors.forename: Johannes
authors.initials: J
authors.lastname: Hüsing
authors.forename: Günter
authors.initials: G
authors.lastname: Marggraf
authors.forename: Frank
authors.initials: F
authors.lastname: Pietruck
authors.forename: Heinz-Günther
authors.initials: HG
authors.lastname: Jakob
authors.forename: Thomas
authors.initials: T
authors.lastname: Philipp
authors.forename: Andreas
authors.initials: A
authors.lastname: Kribben
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000652:urine; D004798:Enzymes / Q000652:urine*; D005260:Female; D006801:Humans; D007683:Kidney Tubular Necrosis, Acute / Q000175:diagnosis* / Q000628:therapy / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011507:Proteinuria / Q000175:diagnosis* / Q000628:therapy / Q000652:urine*; D017582:Renal Replacement Therapy; D012189:Retrospective Studies
chemical_list: D015415:Biomarkers; D004798:Enzymes