Abstract: PD30-06
Sources of Funding: none

Introduction

Percutaneous nephrolithotomy (PCNL) is a transparenchymal procedure that leads to nephron loss during tract access, dilation and instrumentation. Previous studies have demonstrated no significant difference in renal function during uncomplicated PNL. These studies used the Modification of Diet in Renal Disease (MDRD) equation to estimate GFR. This equation is limited in its accuracy for patients with glomerular filtration rates (GFR) > 60 ml/min/1.73 m2. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation provides an accurate estimation of renal function for patients with GFR both above and below 60.Here, we sought to examine factors that may influence changes in GFR as estimated by CKD-EPI. _x000D_

Methods

The last 100 patients that underwent PNL at our institution were reviewed (2014-2015). Pre- and post-operative GFR was calculated based upon both the MDRD and CKD-EPI formulas. Clinical and radiographic parameters were assessed. Statistical difference was determined using Student?s t-test. _x000D_

Results

100 patients were included in the study. All patients had one access tract. Dilation of a 30-French access tract was achieved with a balloon dilator. When using MDRD, 76 of 100 patients were unable to have GFR difference detected due as their GFR exceeded 60 ml/min/1.73 m2. In contrast, pre- and postoperative GFR was able to be compared with all patients using CKD-EPI. The average change in GFR for the entire cohort was +3.39 ml/min/1.73 m2. Patients with stones in three or more locations had a significant decrease in GFR compared with those in one or two locations (-5.7 versus +5.5 ml/min/1.73 m2, p < 0.001). Similarly, patients with stones larger than 4 cm had an average decrease in GFR, while GFR was noted to increase in patients with stones smaller than 4 cm (-4.1 versus +5.5 ml/min/1.73 m2, p = 0.009). In addition, patients with CKD Stage 1 or normal renal function, as well as patients with staghorn stones had a significant comparative decrease in GFR._x000D_

Conclusions

Overall, there was no significant change in GFR among patients that underwent PNL. However, treatment of stones in multiple locations, staghorn stones and treatment of larger stones resulted in a significant decrease in GFR.

Funding

none