title: Upper and lower urinary tract infections can be detected early but not be discriminated by urinary NGAL in adults.
abstract: OBJECTIVE
  We investigated whether the recently established biomarkers of acute kidney injury, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1), may help to diagnose acute urinary tract infections (UTI) in adults and are able to distinguish between upper or lower localization.
  
  
  METHODS
  NGAL levels were measured in blood and urine, and KIM-1 concentrations in urine of 97 subjects. We recruited age- and gender-matched groups of 30 patients with acute upper UTI and 29 patients with acute lower UTI as well as 38 healthy controls. NGAL and KIM-1 were determined by ELISA, serum and urine creatinine applying the Jaffé's method.
  
  
  RESULTS
  Urinary NGAL (uNGAL) was significantly increased in patients with upper as well as with lower UTI compared with the healthy controls (P < 0.01; P < 0.05). Accordingly, uNGAL normalized on urinary creatinine (uNGAL/uCrea) was markedly higher in patients with lower UTI compared with the control group (P < 0.05), and uNGAL/uCrea levels were still raised in patients with upper UTI, though not reaching statistical significance (P = 0.07). However, neither uNGAL nor uNGAL/uCrea levels displayed significant differences between patients with upper or lower UTI (P = 0.75; P = 0.97). uKIM-1 levels were close to the detection limit and too low to reliably reveal differences between the three groups.
  
  
  CONCLUSIONS
  While uKIM-1 seems not to serve as a helpful biomarker in this setting, increased levels of uNGAL indicate inflammatory processes in the urinary tract in adults. However, the determination of uNGAL levels does not allow to differentiate between upper and lower UTI.
authors.affiliation: Faculty of Medicine, Philipps-University Marburg, Baldinger Strasse, 35043, Marburg, Germany, anja.urbschat@staff.uni-marburg.de.
authors.forename: Anja
authors.initials: A
authors.lastname: Urbschat
authors.forename: Nicholas
authors.initials: N
authors.lastname: Obermüller
authors.forename: Patrick
authors.initials: P
authors.lastname: Paulus
authors.forename: Manuel
authors.initials: M
authors.lastname: Reissig
authors.forename: Peyman
authors.initials: P
authors.lastname: Hadji
authors.forename: Rainer
authors.initials: R
authors.lastname: Hofmann
authors.forename: Helmut
authors.initials: H
authors.lastname: Geiger
authors.forename: Stefan
authors.initials: S
authors.lastname: Gauer
mesh_terms: D000208:Acute Disease; D000209:Acute-Phase Proteins / Q000652:urine*; D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000652:urine; D003404:Creatinine / Q000097:blood / Q000652:urine; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D000072596:Hepatitis A Virus Cellular Receptor 1; D006801:Humans; D000071068:Lipocalin-2; D054834:Lipocalins / Q000097:blood* / Q000652:urine*; D008297:Male; D008562:Membrane Glycoproteins / Q000652:urine; D011518:Proto-Oncogene Proteins / Q000097:blood* / Q000652:urine*; D011991:Receptors, Virus; D014552:Urinary Tract Infections / Q000097:blood* / Q000652:urine*
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; C491143:HAVCR1 protein, human; D000072596:Hepatitis A Virus Cellular Receptor 1; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D011991:Receptors, Virus; D003404:Creatinine