Functional Outcomes Following Percutaneous Surgery in the Solitary Kidney

Purpose: We assessed the impact of percutaneous renal surgery on renal function based on the modification of diet in renal disease estimated glomerular filtration rate in solitary renal units. We also determined the variables predictive of functional improvement or impairment following percutaneous surgery in solitary kidneys. Materials and Methods: A prospective database was augmented by retrospective chart review. Between 1984 and 2007, 81 patients with a solitary kidney, which was anatomical in 61.7%, functional in 18.5%, a transplant allograft in 11.1% and unknown in 8.6%, underwent a total of 92 percutaneous procedures. Serum creatinine was measured preoperatively, postoperatively, at 1 month and at 1 year. The 4-variable modification of diet in renal disease equation was used to calculate estimated creatinine clearance. The study population was divided into 3 groups, including group 1-a change in the estimated glomerular filtration rate of 5% or less at 1 year, group 2-an increase of greater than 5% at 1 year and group 3-a decrease of greater than 5% at 1 year. Univariate and multivariate regression analysis was performed using the ordinal logistic fit model to assess the effects of variables on postoperative renal function at 1 year. Results: Percutaneous intervention was performed for stone disease in 64 patients (69.6%), of whom 25 had staghorn calculi. Two patients required concomitant antegrade endopyelotomy for ureteropelvic junction obstruction. Percutaneous resection of transitional cell carcinoma was performed in 28 patients (30.4%). Of the patients 46% had baseline stage 3 chronic kidney disease. Complications developed in 8 patients (8.6%). In the entire cohort the modification of diet in renal disease estimated glomerular filtration rate was 44.7, 42.5, 55.4 and 49.9 ml per minute per 1.73 m(2) at baseline, immediately postoperatively, at 1 month and at 1 year, respectively. Female gender (OR 3.11, p = 0.0038) and an initial postoperative improvement in modification of diet in renal disease estimated glomerular filtration rate of greater than 5% (OR 6.84, p = 0.0026) were predictive of renal function improvement at 1 year on multivariate analysis. Conclusions: Percutaneous renal surgery in the solitary kidney is safe and it results in renal function preservation for up to 1 year of followup. Female gender and an immediate postoperative improvement in the modification of diet in renal disease estimated glomerular filtration rate are predictive of a sustained increase in that rate at 1 year.