title: Clinical significance of tubular and podocyte biomarkers in acute kidney injury.
abstract: BACKGROUND
  Acute kidney injury (AKI) is a common complication in critically ill patients. Urinary excretion of liver-type fatty acid-binding protein (L-FABP), which is expressed in the proximal tubules, reflects the presence of tubular injury. Urinary excretion of podocalyxin (PCX), a glycoprotein prominently expressed on podocytes, is associated with podocyte injury. Our aims were to evaluate the utility of urinary L-FABP for the early detection of AKI and to examine whether podocyte injury is present in AKI patients using the biomarker of urinary PCX.
  
  
  METHODS
  Patients admitted to the intensive care unit (ICU) were divided into the AKI group (n = 14) and non-AKI group (n = 11), according to the occurrence of AKI during hospitalization in the ICU. Changes in various biomarkers were evaluated.
  
  
  RESULTS
  In the AKI group, elevation of urinary L-FABP level [maximum value of L-FABP, 199.0 (92.5-433.6) μg/g creatinine, median (25-75% interquartile range)], which reflects tubular injury (area under the curve 0.95, cut-off value 44.1 μg/g Cr), occurred between -30 and 0 h before the occurrence of AKI (i.e., the time at which serum creatinine peaked), and elevation of urinary PCX level [maximum value of PCX, 389.5 (267.0-501.0) μg/g creatinine; upper limit of reference value, 160 μg/g creatinine] occurred during the time of recovery from AKI when serum creatinine levels were decreasing between 34.0 and 72.0 h after the occurrence of AKI. Furthermore, a parameter with the primary large AUC for predicting the onset of AKI was urinary L-FABP.
  
  
  CONCLUSIONS
  Our study suggests that L-FABP is a useful biomarker for early detection of AKI and that podocyte injury was induced during the recovery phase of AKI.
authors.affiliation: Department of Nephrology and Hypertension, Internal Medicine, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-Ku, Kawasaki, Kanagawa 216-8511, Japan.
authors.forename: Katsuomi
authors.initials: K
authors.lastname: Matsui
authors.forename: Atsuko
authors.initials: A
authors.lastname: Kamijo-Ikemori
authors.forename: Masanori
authors.initials: M
authors.lastname: Hara
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sugaya
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Kodama
authors.forename: Sigeki
authors.initials: S
authors.lastname: Fujitani
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Taira
authors.forename: Takashi
authors.initials: T
authors.lastname: Yasuda
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kimura
mesh_terms: D058186:Acute Kidney Injury / Q000652:urine*; D000293:Adolescent; D000328:Adult; D000369:Aged, 80 and over; D015415:Biomarkers / Q000652:urine*; D003404:Creatinine / Q000097:blood; D042241:Early Diagnosis; D050556:Fatty Acid-Binding Proteins / Q000652:urine*; D005260:Female; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D050199:Podocytes; D012795:Sialoglycoproteins / Q000652:urine*
chemical_list: D015415:Biomarkers; D050556:Fatty Acid-Binding Proteins; D012795:Sialoglycoproteins; C001643:podocalyxin; D003404:Creatinine