title: Prediction of Cortical Defect Using C-Reactive Protein and Urine Sodium to Potassium Ratio in Infants with Febrile Urinary Tract Infection.
abstract: OBJECTIVE
  We investigated whether C-reactive protein (CRP) levels, urine protein-creatinine ratio (uProt/Cr), and urine electrolytes can be useful for discriminating acute pyelonephritis (APN) from other febrile illnesses or the presence of a cortical defect on 99mTc dimercaptosuccinic acid (DMSA) scanning (true APN) from its absence in infants with febrile urinary tract infection (UTI).
  
  
  METHODS
  We examined 150 infants experiencing their first febrile UTI and 100 controls with other febrile illnesses consecutively admitted to our hospital from January 2010 to December 2012. Blood (CRP, electrolytes, Cr) and urine tests [uProt/Cr, electrolytes, and sodium-potassium ratio (uNa/K)] were performed upon admission. All infants with UTI underwent DMSA scans during admission. All data were compared between infants with UTI and controls and between infants with or without a cortical defect on DMSA scans. Using multiple logistic regression analysis, the ability of the parameters to predict true APN was analyzed.
  
  
  RESULTS
  CRP levels and uProt/Cr were significantly higher in infants with true APN than in controls. uNa levels and uNa/K were significantly lower in infants with true APN than in controls. CRP levels and uNa/K were relevant factors for predicting true APN. The method using CRP levels, u-Prot/Cr, u-Na levels, and uNa/K had a sensitivity of 94%, specificity of 65%, positive predictive value of 60%, and negative predictive value of 95% for predicting true APN.
  
  
  CONCLUSIONS
  We conclude that these parameters are useful for discriminating APN from other febrile illnesses or discriminating true APN in infants with febrile UTI.
authors.affiliation: Department of Pediatrics, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Jung
authors.affiliation: Department of Pediatrics, CHA Bundang Medical Center, CHA University, Seongnam, Korea. naesusana@gmail.com.
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000208:Acute Disease; D002097:C-Reactive Protein / Q000032:analysis*; D016022:Case-Control Studies; D005334:Fever / Q000382:microbiology; D006801:Humans; D007223:Infant; D008297:Male; D011188:Potassium / Q000652:urine*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011507:Proteinuria / Q000175:diagnosis; D011704:Pyelonephritis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D012964:Sodium / Q000652:urine*; D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D014552:Urinary Tract Infections / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000382:microbiology
chemical_list: D019783:Technetium Tc 99m Dimercaptosuccinic Acid; D002097:C-Reactive Protein; D012964:Sodium; D011188:Potassium
keywords: C-reactive protein; Pyelonephritis; proteinuria; urine sodium-potassium ratio