Silent ureteral stones: impact on kidney function--can treatment of silent ureteral stones preserve kidney function?

OBJECTIVE To report our experience with silent ureteral stones and expose their true influence on renal function. METHODS We analyzed 506 patients who had undergone ureterolithotripsy from January 2005 to May 2010. Silent ureteral stones were calculi found in the absence of any specific or subjective ureteral stone-related symptoms. Of the 506 patients, 27 (5.3%) met these criteria (global cohort). All patients were assessed postoperatively with dimercaptosuccinic acid scintigraphy (DMSA). A difference in relative kidney function of >10% was considered abnormal. Pre- and postoperative comparative DMSA analyses were electively obtained for 9 patients (kidney function cohort). A t test was used to assess the numeric variables, and the chi-square test or Fisher's exact test was used for categorical variables. Two-tailed P<.05 was considered statistically significant. RESULTS Stones were diagnosed by radiologic abdominal evaluation for nonurologic diseases in 40% and after previous nephrolithiasis treatment in 33%. The primary therapy was ureterolithotripsy in 88%. The mean follow-up time was 23 months. The overall ureteral stone-free rate after 1 and 2 procedures was 96% and 100%, respectively. In the global cohort, the mean pre- and postoperative serum creatinine levels were similar (P=.39), and the mean postoperative function on DMSA was 31%. In the kidney function cohort, no difference was found between the pre- and postoperative DMSA findings (22%±12.1% vs 20%±11.8%; P=.83) and serum creatinine (0.8±0.13 mg/dL vs 1.0±0.21 mg/dL; P=.45). CONCLUSION Silent ureteral stones are associated with decreased kidney function present at the diagnosis. Hydronephrosis tends to diminish after stone removal, and kidney function remains unaltered.