STONE DISEASE

Impact of percutaneous nephrolithotomy on estimated glomerular filtration rate in patients with chronic kidney disease
Bilen CY, Inci K, Kocak B, Tan B, Sarikaya S, Sahin A
Department of Urology, Hacettepe University School of Medicine, Ankara, Turkey
J Endourol. 2008; 22: 895-900

• Background and Purpose: We investigated the impact of percutaneous renal procedures on estimated glomerular filtration rate (GFR) of patients with chronic kidney disease (CKD).
• Patients and Methods: The GFRs of adult patients were calculated using the Modification of Diet in Renal Disease formula, and the patients were staged according to the Kidney Disease Outcome Quality Initiative CKD classification system. The study included 185 patients with preoperative GFR values less than 60 mL/min/1.73 m(2). The impact of percutaneous nephrolithotomy (PCNL) on GFR was analyzed by comparing the preoperative GFR with the GFR before discharge and at postoperative month 3.
• Results: Patients with CKD had a significant increase in the GFR after the procedure. In postoperative month 3, the mean GFR was more than 60 mL/min/1.73 m(2) in 25% of the patients with CKD and less than 60 mL/min/1.73 m(2) in 75%. While all patients with stage 5 CKD improved to better stages, some other patients’ conditions declined to stage 5 from better stages at the end of postoperative month 3. No patient needed dialysis. The presence of urinary tract infections tended to affect GFR negatively.
• Conclusion: Estimated GFR, as a better indicator of renal function, is significantly affected by the PCNL procedure. While significant improvement was observed in late-stage patients with CKD, unexpected deterioration could occur in patients at earlier stages.
  
  
• Editorial Comment
  The investigators studied a challenging patient population - the high rate of staghorn calculi and high rate of multiple accesses suggest a complex stone burden. This certainly may account for the high complication rates, specifically related to transfusion, sepsis and death. Alternatively, it is possible that the CKD could impact platelet function, baseline hemoglobin, cell-mediated immunity and humoral defenses. It is possible that the higher rate of urinary leak could be related to the thinned renal parenchyma in CKD. Interestingly, number of renal accesses or presence of a solitary kidney did not predict a negative outcome on GFR. Intuition would suggest that in these high risk patients, a greater reliance on flexible ureteroscopy and nephroscopy to decrease the need for multiple accesses might be warranted. One can conclude that GFR often improves after PCNL, however occasionally renal function will worsen. Patients should be counseled on the 25% chance of improvement and 4% risk of deterioration.

Dr. Manoj Monga
Professor, Department of Urology
University of Minnesota
Edina, Minnesota, USA
E-mail: endourol@yahoo.com