title: Nature and fate of supranormal differential renal function: lessons from long-term follow-up after pyeloplasty.
abstract: OBJECTIVE
  To understand the nature and long-term fate of supranormal differential renal function (snDRF), analysis of a post-pyeloplasty database was performed.
  
  
  METHODS
  Preoperative diethylenetriaminepentaacetic acid (DTPA) diuretic renal scans (DRS) identified 33 children with snDRF (>55%). Postoperatively, all showed improved hydronephrosis in ultrasound imaging or normalized drainage pattern in DRS during more than 5 years of follow-up. The fate of snDRF was described, and the nature of snDRF was speculated by associating it with clinical and ultrasound-related variables.
  
  
  RESULTS
  Median age at operation was 22 months. Preoperative hydronephrosis was grade III in 27 patients (82%) and grade IV in 6 (18%). Hydronephrosis was normalized or improved, showing relief of obstruction. Overall fate of snDRF revealed significant reduction of DRF in 23 patients (70%), of whom 18 (81%) showed normalization during 5 years of follow-up. Stationary change of snDRF was seen in one-third of patients. Comparison of clinical and ultrasound-related variables revealed lower age, lower renal parenchyma thickness (RPT) increase, and higher preoperative DRF in the normalized group compared with the other group. The normalized group also showed a higher number in Society of Fetal Urology grade 4 hydronephrosis and lower RPT, although they reached borderline statistical significance.
  
  
  CONCLUSIONS
  Long-term follow-up revealed that 70% of snDRF significantly decreased and normalized in most patients. The normalized group was younger and showed more hydronephrotic changes. Hydronephrotic change is suggested as a possible cause of snDRF.
authors.affiliation: Department of Urology, Seoul Municipal Boramae Hospital, Seoul, Korea.
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Cho
authors.forename: In Sung
authors.initials: IS
authors.lastname: Kim
authors.forename: Seung-Bae
authors.initials: SB
authors.lastname: Lee
authors.forename: Hwang
authors.initials: H
authors.lastname: Choi
authors.forename: Kwanjin
authors.initials: K
authors.lastname: Park
mesh_terms: D002614:Chelating Agents; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006869:Hydronephrosis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery; D007223:Infant; D007668:Kidney / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007677:Kidney Function Tests; D008297:Male; D004369:Pentetic Acid; D011868:Radioisotopes; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D013667:Technetium; D013997:Time Factors; D014517:Ureteral Obstruction / Q000150:complications / Q000601:surgery
chemical_list: D002614:Chelating Agents; D011868:Radioisotopes; D013667:Technetium; D004369:Pentetic Acid