MP51-17 IMPACT OF PERCUTANEOUS NEPHROLITHOTRIPSY ON EARLY AND LONG-TERM RENAL FUNCTION IN PATIENTS WITH A SOLITARY KIDNEY

Abstract

INTRODUCTION AND OBJECTIVES: The impact of percutaneous nephrolithotripsy (PCNL) on renal function is an especially important consideration in stone formers with solitary kidneys. The objectives of this study were to evaluate the effect of PCNL on kidney function and further characterize patient demographics and perioperative outcomes of this unique cohort. METHODS: A retrospective review of medical records was performed on patients with a solitary or single functioning renal unit who underwent PCNL at a single institution between 1990 and 2013. Data on early and long-term post-operative renal function were collected and analyzed. Patient demographics and perioperative factors were compared to our larger cohort of PCNL patients and evaluated as potential predictors of post-operative renal function. RESULTS: Of 2318 patients, there were 76 PCNL events for patients with a solitary renal unit (40 female and 36 male). Long-term data (over 2 years post-operatively) was available for 48 PCNL events (24 female and 24 male). Estimated glomerular function (eGFR) slightly worsened in the early post-operative period, from 51 2.9 to 47 2.7 ml/min/1.73m2 (p <0.01). In the long-term however, eGFR improved, from 48 3.7 to 57 5.9 ml/min/1.73m2 (p <0.02). Predominant stone compositions included 19.7% cysteine, 19.7% calcium oxalate monohydrate and 11.8% and struvite. Compared to the larger cohort of PCNL patients, age, sex, complications, and stone free rates were consistent. Patients with solitary kidneys had more medical co-morbidities (64.7% vs 45%), with higher rates of diabetes (18.4% vs 13%) and pre-existing renal impairment (18.4% vs 3%). Univariate analyses of patient age, sex, comorbidities, stone composition, stone size, number of tracts and stone free rates were unable to identify a significant predictor of early and long-term postoperative renal function. CONCLUSIONS: These results show that while in the early post-operative period renal function slightly declines, it recovers in the long-term post PCNL for patients with solitary kidneys. Based on these findings, PCNL correlates with overall improved long-term renal function in patients with solitary kidneys. Given the higher rate of pre-existing medical co-morbidity and likely history of recurrent stone disease (high rates of cysteine and struvite stones), this solitary kidney cohort is presumably a high-risk population for future renal impairment. This further emphasizes the need to preserve renal function with PCNL in stone formers with solitary kidneys.