STONE DISEASE

Nephrolithiasis associated with renal insufficiency: factors predicting outcome
Kukreja R, Desai M, Patel SH, Desai MR
Department of Urology, Muljibhai Patel Urological Hospital, Dr. V.V. Desai Road, Nadiad, Gujarat 387001, India
J. Endourol. 2003; 17: 875-9

• Background and Purpose: Renal calculous disease may be associated with various degrees of renal insufficiency secondary to a combination of obstruction, urinary infection, frequent surgical intervention, and coexisting medical disease. Herein, we present our data on the progression of renal function in patients with stones associated with renal insufficiency and assess the significance of various factors that could predict postoperative renal function deterioration.
• Patients and Methods: Data were obtained from 4400 patients undergoing treatment for calculous disease at our institute since 1991. Renal insufficiency, defined as a baseline serum creatinine > 1.5 mg/dL, was present in 84 (1.9%). Predictive factors evaluated for renal function deterioration were preoperative (age, duration of symptomatology and nephrolithiasis, urinary tract infection, coexistent medical diseases, baseline serum creatinine, and stone burden), intraoperative (number of percutaneous tracts), and postoperative (recurrent infection, proteinuria, cortical atrophy, residual fragments, and stone recurrence).
• Results: Over a mean follow-up of 2.2 years (range 6 months-6 years), 33 patients (39.3%) showed improvement, 24 (28.6%) showed stabilization, and 27 (32.1%) showed deterioration in their renal function. Higher baseline serum creatinine, proteinuria > 300 mg/day, renal cortical atrophy, stone burden > 1500 mm(2), recurrent urinary infection, and age < 15 years were significant predictors of subsequent renal function deterioration.
• Conclusions: Patients with nephrolithiasis and mild to moderate renal insufficiency warrant aggressive treatment aimed at complete stone clearance and prevention of recurrence of stones and urinary infection. A higher baseline preoperative serum creatinine, proteinuria > 300 mg/day on follow-up, renal cortical atrophy, stone burden > 1500 mm(2), recurrent urinary infection, and age < 15 years are associated with a significantly higher likelihood of renal function deterioration after treatment of the calculous disease.
  
  
• Editorial Comment
  Although the short-term goal in treating obstructing renal and ureteral calculi is relief of pain and obstruction, the long-term goal is preservation of renal function. However, in some cases damage to renal parenchyma is irreversible and renal function is not fully recovered. Kekreja and colleagues reviewed their series of 4400 patients undergoing surgical management for renal or ureteral stones and identified 84 patients with renal insufficiency despite stabilization with nephrostomy drainage. At a mean of 2.2 years of follow-up, 32% of patients had deterioration in their renal function, and 44% of those went on to end-stage renal failure and dialysis. Among a variety of factors assessed, age < 15 years, atrophic renal parenchyma, large stone burden, significant proteinuria and recurrent urinary tract infections were found to be significant predictors of post-operative renal deterioration. Moreover, for patients with a pre-operative serum creatinine = 3, deterioration of renal function occurred during follow-up in 54% of patients, with a direct correlation between preoperative serum creatinine and post-operative renal deterioration.
  This study suggests that although most patients with stones and mild renal insufficiency can avert further renal functional loss with aggressive treatment to remove stones and prevent recurrent stones and infection, the outcome for patients who have already sustained significant renal damage is poor despite aggressive surgical management. Furthermore, for patients with any of the poor prognostic factors determined in this study, renal functional deterioration is more likely. Nevertheless, complete stone clearance and careful follow-up is recommended for all patients with stones and renal insufficiency in hopes of maximally preserving renal function and delaying renal functional deterioration.

Dr. Margaret S. Pearle
Associate Professor of Urology
University of Texas Southwestern Med Ctr
Dallas, Texas, USA