title: Preoperative nuclear renal scan underestimates renal function after radical nephrectomy.
abstract: OBJECTIVE
  To compare expected and actual renal function after nephrectomy. Nuclear renal scan estimates differential kidney function and is commonly used to calculate expected postoperative renal function after radical nephrectomy. However, the observed postoperative renal function is often different from the expected.
  
  
  METHODS
  A retrospective review was performed on 136 patients who underwent radical nephrectomy or nephroureterectomy and had a preoperative renal scan with calculated differential function.
  
  
  RESULTS
  Glomerular filtration rate (GFR) values, preoperative and postoperative, were calculated with the Modification of Diet in Renal Disease (MDRD) equation. The expected postoperative GFR based on renal scan was compared with the actual postoperative GFR. The average age of patients undergoing surgery was 58.6 years, and the indication for surgery was for benign causes in 59 (44%) patients and cancer in 76 (56%) patients. The average preoperative creatinine and estimated GFR were 1.0 mg/dL and 69.9 mL/min/1.73 m(2). At a median follow-up of 3.3 months, the actual postoperative GFR exceeded the expected GFR by an average of 12.1% (interquartile range, 2.6%-25.2%). When stratified by preoperative GFR >90, 60-90, and <60 mL/min/1.73 m(2), respectively, the observed GFR exceeded the expected GFR by 4.3%, 12.6%, and 14.9%, respectively (P = .16). This trend was maintained when GFR was plotted over time.
  
  
  CONCLUSIONS
  After nephrectomy, the remaining kidney exceeded the expected postoperative GFR by 12% in this cohort of patients with preoperative renal scans. Patients with existing renal insufficiency had the greatest compensatory response, and this was durable over time.
authors.affiliation: Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, IL.
authors.forename: Laurie
authors.initials: L
authors.lastname: Bachrach
authors.affiliation: Division of Urology, University of Chicago, Chicago, IL.
authors.forename: Edris
authors.initials: E
authors.lastname: Negron
authors.affiliation: Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, IL.
authors.forename: Joceline S
authors.initials: JS
authors.lastname: Liu
authors.affiliation: Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, IL.
authors.forename: Yu-Kai
authors.initials: YK
authors.lastname: Su
authors.affiliation: Department of Nephrology, Northwestern University Feinberg School of Medicine, Chicago, IL.
authors.forename: James J
authors.initials: JJ
authors.lastname: Paparello
authors.affiliation: Division of Urology, University of Chicago, Chicago, IL.
authors.forename: Scott
authors.initials: S
authors.lastname: Eggener
authors.affiliation: Department of Urology, Northwestern University Feinberg School of Medicine, Chicago, IL. Electronic address: skundu@nmff.org.
authors.forename: Shilajit D
authors.initials: SD
authors.lastname: Kundu
mesh_terms: D000368:Aged; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000601:surgery*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000009:adverse effects / Q000379:methods*; D011184:Postoperative Period; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D003404:Creatinine