title: Comparative Outcome Analysis of Children Who Underwent Pyeloplasty for Ureteropelvic Junction Obstruction Associated With or Without Supranormal Differential Renal Function.
abstract: OBJECTIVE
  To compare pyeloplasty outcomes in children with and without "supra-normal" differential renal function (SNDRF) defined as >55% differential renal function (DRF) in children with ureteropelvic junction obstruction.
  
  
  METHODS
  Our prospectively collected pyeloplasty database (2008-2015) was reviewed (n = 151). A total of 140/151 (93%) patients had preoperative renograms and 26/140 (19%) were found to have SNDRF (DRF ≥ 55%). Of 151 patients, 51 (34%) had pre- and postoperative renograms allowing determination of change ≥5% in function. After excluding 2 patients with solitary kidneys, a total of 49 patients defined the study group.
  
  
  RESULTS
  Of 49 patients, 12 had SNDRF and 37 did not. Baseline characteristics were similar including mean age at surgery (47.3 months vs 45.4 months) and time to surgery (8.7 months vs 9.8 months). Mean preoperative anteroposterior diameter was significantly different between groups (23.2 mm vs 31.0 mm; P = .04), but postoperative was similar (9.0 mm vs 12.1 mm; P = .14). Mean preoperative DRF was 60.2% in the SNDRF group vs 44.3% in the non-SNDRF. Mean postoperative DRF was 52.4% and 45.3%, respectively (P = .04). There were 9/12 (75%) SNDRF patients who experienced ≥5% loss in function compared to 2/37 (5%) in the non-SNDRF group (P < .01).
  
  
  CONCLUSIONS
  Three-quarters of SNDRF patients demonstrated a decline of ≥5%DRF postoperatively when compared to non-SNDRF. This finding may not reflect true elevated renal function, but rather hyperfiltration in the setting of obstruction, which-if unrecognized as such-could result in postponing an otherwise beneficial surgical intervention.
authors.affiliation: McMaster University/McMaster Children's Hospital, Hamilton, Ontario, Canada; Clinical Urology Research Enterprise (CURE) Program, McMaster Children's Hospital, Hamilton, Ontario, Canada.
authors.forename: Mandy
authors.initials: M
authors.lastname: Rickard
authors.affiliation: McMaster University/McMaster Children's Hospital, Hamilton, Ontario, Canada; Clinical Urology Research Enterprise (CURE) Program, McMaster Children's Hospital, Hamilton, Ontario, Canada; McMaster Pediatric Surgery Research Collaborative, Hamilton, Ontario, Canada. Electronic address: braga@mcmaster.ca.
authors.forename: Luis H
authors.initials: LH
authors.lastname: Braga
authors.affiliation: Clinical Urology Research Enterprise (CURE) Program, McMaster Children's Hospital, Hamilton, Ontario, Canada.
authors.forename: Shreyas
authors.initials: S
authors.lastname: Gandhi
authors.affiliation: Clinical Urology Research Enterprise (CURE) Program, McMaster Children's Hospital, Hamilton, Ontario, Canada.
authors.forename: John-Paul
authors.initials: JP
authors.lastname: Oliveria
authors.affiliation: McMaster University/McMaster Children's Hospital, Hamilton, Ontario, Canada; Clinical Urology Research Enterprise (CURE) Program, McMaster Children's Hospital, Hamilton, Ontario, Canada; McMaster Pediatric Surgery Research Collaborative, Hamilton, Ontario, Canada.
authors.forename: Jorge
authors.initials: J
authors.lastname: Demaria
authors.affiliation: Division of Urology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Armando J
authors.initials: AJ
authors.lastname: Lorenzo
mesh_terms: D002675:Child, Preschool; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007677:Kidney Function Tests; D007682:Kidney Pelvis / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D011184:Postoperative Period; D011866:Radioisotope Renography; D019651:Plastic Surgery Procedures / Q000379:methods*; D016896:Treatment Outcome; D014513:Ureter / Q000601:surgery; D014517:Ureteral Obstruction / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D014563:Urodynamics / Q000502:physiology; D013520:Urologic Surgical Procedures / Q000379:methods*