title: Do multiple ureteroscopies alter long-term renal function? A study using estimated glomerular filtration rate.
abstract: OBJECTIVE
  Although considered standard of care for symptomatic urolithiasis, few data are available that evaluate the effects of multiple ureteroscopies (URS) with laser lithotripsies on long-term renal function. We investigated this relationship in a population with preexisting mild to moderate kidney disease. Previous studies have been limited by estimates of glomerular filtration rate (eGFR) calculated from creatinine level during acute stone obstruction, and inclusion of patients with a history of other stone procedures, such as shockwave lithotripsy (SWL) or percutaneous nephrolithotomy (PCNL).
  
  
  METHODS
  Charts were reviewed for patients with a baseline eGFR below 90 mL/min/1.73 m(2) who underwent at least two URS for nephrolithiasis at our institution from 2004 to 2012. Patients undergoing SWL or PCNL at any point in their history were excluded. A total of 26 patients, with a mean of 2.3±0.6 URS procedures, were included. The eGFR was recorded at baseline before acute stone presentation and surgery, and at the last recorded follow-up visit. Stone location, total stone burden, and comorbidities were also recorded.
  
  
  RESULTS
  The mean eGFR changed from 68.0±13.3 to 75.4±23.0 mL/min/1.73m(2) (mean increase of 10.1±25.0%; mean annual increase of 3.8±15.3%) over a mean follow-up period of 28.1 months (range 5-75 mos). There was no significant difference in eGFR change between patients with stones treated in the kidney alone vs the ureter and kidney combined (12.1% vs 8.3% mean increase; P=0.74). Age, presence of diabetes mellitus or hypertension, baseline creatinine level, total stone burden, and number of URS performed were not significantly associated with change in eGFR.
  
  
  CONCLUSIONS
  Using eGFR measured before acute stone presentation, our results suggest that multiple ureteroscopies for stones are not detrimental to long-term renal function, even in patients with preexisting stage 2-3 chronic kidney disease.
authors.affiliation: 1 Department of Urology, University of Wisconsin School of Medicine and Public Health , Madison, Wisconsin.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Sninsky
authors.forename: R Allan
authors.initials: RA
authors.lastname: Jhagroo
authors.forename: Brad C
authors.initials: BC
authors.lastname: Astor
authors.forename: Stephen Y
authors.initials: SY
authors.lastname: Nakada
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D007669:Kidney Calculi / Q000150:complications / Q000503:physiopathology / Q000601:surgery*; D008096:Lithotripsy / Q000379:methods; D017602:Lithotripsy, Laser / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D051437:Renal Insufficiency / Q000209:etiology / Q000503:physiopathology*; D018666:Ureteroscopy / Q000009:adverse effects* / Q000379:methods