Long-Term Renal Function and Stone Recurrence After Percutaneous Nephrolithotomy in Patients with Renal Insufficiency

Abstract

Purpose:

We analyzed long-term results after percutaneous nephrolithotomy (PCNL) in patients with impaired renal function.

Patients and Methods:

Nineteen (6.3%) of 300 patients who underwent PCNL had serum creatinine values above 1.4 mg/dL before surgery and were considered to have impaired renal function. Success rate of operation, recurrence rate, and renal functional status were evaluated.

Results:

Mean follow-up time was 51.1 ± 10.1 months. Sixteen patients completed the study, but three patients were lost to follow-up. The results of the operation were as follows: stone free in 50%, clinically insignificant residual fragments in 25%, and clinically significant residual fragments in 25% of the patients. Mean serum creatinine value was 2.30 ± 0.56 mg/dL before surgery and 2.67 ± 1.41 mg/dL at the end of follow-up (p = 0.386). Creatinine values decreased to normal range in six patients (37.5%). Six patients (37.5%) had stable renal function (creatinine: 1.4–4 mg/dL). Creatinine values increased (>4 mg/dL) in four patients (25%) who required renal replacement therapy. Three new patients progressed to end-stage renal failure. These three had insulin-dependent type II diabetes mellitus and one also had solitary kidney and atherosclerosis. Two patients (12.5%) had recurrences, one of these had hypercalciuria, and the other had infection stone.

Conclusion:

Our results indicated that most patients presenting with kidney-stone disease and renal insufficiency experience improvement or stabilization of renal function after PCNL. The patients with solitary kidney and those with conditions such as diabetes and atherosclerosis might be at greater risk for deterioration of renal function. Patients with metabolic abnormalities and infection stones might be at higher risk for recurrence.

Introduction

P rogress in the minimally invasive treatment of kidney stones has enabled urologists to successfully treat patients with comorbid diseases, such as those with impaired renal function (IRF). Patients with renal insufficiency compose 0.78% to 17.5% of patients treated for kidney stones in different series.^1
–3 This group may require a combination of various treatment modalities to obtain successful results. Gupta and coworkers¹ reported that 75.8% of urolithiasis patients with mild to moderate renal insufficiency required multiple procedures including shockwave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), and ureteroscopic procedures, and even open surgery. We have previously reported that similar stone clearance rates can be obtained with PCNL without a significant increase in complications in patients with IRF compared with those with normal renal function (NRF).⁴ In this study, we analyzed the long-term renal function and stone recurrence rates after PCNL in patients with IRF.

Patients and Methods

Three hundred consecutive patients underwent PCNL for the treatment of kidney stones from July 2002 to July 2005 in a single center. Nineteen patients (6.3%) had serum creatinine values above 1.4 mg/dL (normal 0.3–1.4 mg/dL) in at least two measurements within 4 weeks before surgery. These patients were considered to have IRF. The remaining patients were considered to have NRF. The lowest creatinine value obtained before surgery was accepted as the baseline creatinine level of the patient. For patients with acute exacerbation of renal failure caused by urinary infection or obstruction, the lowest creatinine value obtained after the relief of obstruction and infection and stabilization of renal function was used. No patients with acute renal failure were included. Our management strategy before and immediately after surgery were described previously.⁴ Briefly, this strategy included decompression of the obstructed units, culture-specific antibiotic treatment of those with urinary tract infection, transfusions for those with severe anemia, nephrology consultation for the control of hypertension as well as the planning of renal replacement therapy before and after surgery as necessary.

All of the operations were performed in a single center under general anesthesia by any member of a team of four urologists. After ureteral catheterization in lithotomy position, the patients were tilted to prone position. The pyelocaliceal system was approached with the insertion of an 18-gauge Chiba needle toward the opaque stone after viewing the stone with fluoroscopy. After tract dilatation, a renal sheath was placed leaving a safety guidewire in place and nephroscopy was performed with a rigid nephroscope. A pneumatic lithotripter was used for stone fragmentation. The stone fragments were extracted by forceps. A 16F to 18F reentry nephrostomy catheter was placed at the end of the operation.

The success rate of the operation was evaluated in four categories: stone free (SF), clinically insignificant residual fragments (CIRF, residual fragments smaller than 4 mm), clinically significant residual fragments (CSRF, residual fragments larger than 4 mm), and failure.

The patients were controlled with blood chemistry, urine culture, plain radiography, and computerized tomography 3 months after surgery. Then, they were followed with blood chemistry, urine culture, plain radiography, and ultrasonography at every 6 months afterward. Additional radiologic and laboratory investigations were performed as deemed necessary. The patients were followed-up until January 2009. The serum creatinine values before PCNL and at the end of follow-up were compared to assess the long-term effect of PCNL on renal function. New stone formation or increase in the size of residual fragments was noted as stone recurrence. Any additional treatment during follow-up period was noted. Progression to end-stage renal disease (ESRD) and need for replacement therapy (hemodialysis or peritoneal dialysis) were also investigated.

Statistical analysis was performed with Statistical Package for Social Sciences 15.0 for Windows. The creatinine levels were compared by the paired samples t-test, and the p-values of <0.05 were accepted to be significant.

Results

Three patients in the IRF group were lost to follow-up during the study period. Thus, 12 men and 4 women patients completed the study. One of the patients had bilateral renal calculi and thus PCNL was performed on 17 kidneys; four patients had solitary kidneys. Initially, 11 of the 17 kidneys (65%) were stented (six double pigtail stents and five percutaneous nephrostomy tubes) for the relief of obstruction and/or infection before PCNL. Urine cultures were positive for urinary infection in six (37.5%). The mean stone area was 1484 ± 1333 mm². Four kidneys (24%) had complete, 10 kidneys (59%) had partial staghorn stones, and 4 kidneys (24%) had nonopaque stones.

The results of PCNL were SF in 50%, CIRF 25%, and CSRF in 25% of the patients. Two patients (25%) with CSRF underwent SWL for adjunctive treatment in the early postoperative period. Two (25%) patients with CIRF had uric acid stones and they were additionally treated with chemolysis by urine alkalinization with potassium citrate. Stone analyzes revealed that stone types were calcium oxalate in nine patients, uric acid in two patients, uric acid and calcium oxalate in two patients, magnesium ammonium phosphate stones in two patients, and calcium phosphate and oxalate in one patient. Complications occurred in five cases during or early after PCNL. These were noted as blood loss requiring transfusion in three cases; blood loss requiring transfusion and anuria due to ureteral obstruction caused by stone fragments in one case, and emergency admission because of colicky pain in one case.

The mean follow-up time was 51.1 ± 10.1 (range: 39–69) months. Mean serum creatinine value was 2.30 ± 0.56 mg/dL before surgery and 2.67 ± 1.41 mg/dL at the end of follow-up period. This slight increase was not statistically significant (p = 0.386). However, serum creatinine values decreased to normal range (<1.4 mg/dL) in six patients (37.5%) at the end of the follow-up period. Six patients (37.5%) had stable renal function with serum creatinine levels between 1.4 and 4 mg/dL. Serum creatinine values increased (>4 mg/dL) in four patients (25%) at the end of the follow-up period and required renal replacement therapy. Two patients were on hemodialysis before surgery. One patient who had been on hemodialysis for 4 months showed improvement of renal function, and hemodialysis was discontinued after PCNL. However, three patients who were not on renal replacement therapy before PCNL progressed to end-stage renal failure and were put on routine hemodialysis program during the follow-up period. These three patients had insulin-dependent type II diabetes mellitus and one of them also had solitary kidney and atherosclerosis (Table 1). No surgical complications that could have facilitated the deterioration of renal function were identified in these patients.

Table 1.

Characteristics of the Patients Who Progressed to End-Stage Renal Failure

Patients	Age (years)	Sex	Initial end-stage renal failure	Diabetes mellitus	Hypertension	Solitary kidney	Atherosclerosis
Patient 1	58	Male	+	−	−	−	−
Patient 2	65	Male	−	+	−	−	−
Patient 3	60	Female	−	+	−	−	−
Patient 4	59	Male	−	+	−	+	+

During long-term follow-up, two patients (12.5%) who were rendered SF after PCNL had recurrences. One patient who had hypercalciuria had stone recurrence in both kidneys despite medical treatment with potassium citrate and thiazide diuretics and undergoing bilateral SWL and ureteroscopy procedures. Another patient with struvite stone had multiple recurrences in the opposite kidney and was treated with multiple SWL procedures. No other patient had any recurrences or underwent additional procedures for stone treatment.

In NRF group, a cohort of 20 patients were randomly chosen for comparison from our PCNL database of 300 patients. Twenty PCNL procedures were performed to 20 kidneys in this group. The mean stone area of these patients was 600 ± 345 mm². The results of PCNL were SF in 80%, CIRF in 10%, and CSRF in 10% of the patients. The mean follow-up time was 29 ± 6 (range: 17–34) months. Mean serum creatinine value was 0.81 ± 0.16 mg/dL before surgery and 0.82 ± 0.19 mg/dL at the end of follow-up period. This slight increase was not statistically significant (p = 0.656). During long-term follow-up, three patients (15%) who had become SF soon after PCNL operation had recurrences.

Discussion

PCNL has become the mainstay of treatment for large renal calculi over the past 30 years. Several improvements and modifications have helped to decrease the morbidity of PCNL, including regional blocks, single-step dilatations, miniperc technique, tubeless PCNL, and sandwich therapy.^5

–9 The improvements in the technique and increase in the experience of the urologists provide a more regular, effective, and safer treatment of kidney stone disease with PCNL. Consequently, PCNL has also become one of the main treatment modalities for kidney stones of patients with comorbid diseases such as obesity and IRF.

In the 300 consecutive patients who underwent PCNL at our institution, 19 patients (6.3%) had IRF defined as serum creatinine level greater than 1.4 mg/dL.

The presence of kidney stones in patients with IRF requires special consideration. Renal failure is frequently a progressive condition and the presence of stones in the urinary tract may accelerate the course of the disease. Obstruction and infection are responsible for renal function deterioration in the patients with renal stones.¹⁰ The changes in the kidney parenchyma caused by infection become more pronounced with concomitant obstruction. Duration of the stone disease, multiple procedures, and stone recurrence also have negative effects on renal function.¹¹ Therefore, the management of kidney stone disease in the patients with IRF plays an important role in improving the renal function and helps to avoid the need for renal replacement therapy. On the other hand, there is concern for the detrimental effect of surgical and endourologic procedures on kidney function and the possibility of increased complications in patients with kidney failure. In 1980, Witherow and Wickham¹² had reported the significant increase in mean creatinine clearances after nephrolithotomy in patients with IRF due to stone disease. However, laboratory and clinical studies have shown that percutaneous procedures cause no significant damage to functional nephrons.^13
–15

In this study, after 51.1 ± 10.1 months of follow-up period, an insignificant increase in the mean value of serum creatinine was seen in the IRF group. Serum creatinine values decreased to normal range in six patients (37.5%) and stabilized at the 1.4 to 4 mg/dL range in six patients (37.5%). Before surgery, two patients (12.5%) were on hemodialysis, and after a long-term follow-up a total of four patients (25%) required renal replacement therapy. We did not identify any PCNL-related factors that caused deterioration of renal function, even in patients with solitary kidney. However, patients who have solitary kidney and those who have conditions such as diabetes and atherosclerosis might be at greater risk for progression to ESRD in long-term follow-up. In the NRF group, there was no statistical difference between creatinine values before surgery and at the end of 29 ± 6 months follow-up.

Table 2 shows the data on long-term fate of renal function in a series that reported the results for PCNL in patients with IRF. Gupta and coworkers¹ identified 33 patients (1.65%) with urinary stone and mild to moderate renal insufficiency. The patients underwent multiple procedures consisting of PCNL, SWL, ureteroscopic stone extractions, and alkalinization. After a 3- to12-month follow-up, there was a significant decrease in the mean creatinine value of the patients after kidney stone treatment. Long-term follow-up data were available in 13 of 33 patients, 4 patients (31%) had progression of intrinsic renal disease and had ESRD 5 years after the initial operation and the remaining 9 patients (69%) had stabilized their renal function. Although the long-term follow-up period of this study is similar to ours, many patients progressed to ESRD and no patients had normalization of renal function at the end of long-term follow-up. However, long-term data were not available for almost two-thirds of the whole group. It is possible that the patients who have normalization of serum creatinine values were more likely to be lost to follow-up. Kukreja and coworkers² treated 84 patients with kidney stone disease and IRF. Primary surgical treatment was PCNL but some patients underwent nephrolithotomy and nephrectomy as well. Over a relatively short mean follow-up of 2.20 ± 1.34 years, overall renal function improved in 33 patients (39%), stabilized in 24 patients (29%), and deteriorated in 27 patients (32%). Twelve patients (14%) went on to ESRD requiring dialysis. Agrawal and coworkers³ performed PCNL in 78 patients with IRF. During a follow-up of 1.5 to 9 years, 82% of the patients had improvement in renal function and 14% had stabilized renal function. The renal function improvement rates of this study seem to be higher than ours; however, they also reported a 4% mortality rate due to septic complications. In the series reported by Jones and coworkers,¹⁶ all patients had solitary kidney and abnormal renal function at presentation. In this group, one patient (7%) had progressed to chronic renal failure and two patients (14%) had improvement in the renal function after 4 to 29 months follow-up.

Table 2.

Data on Long-Term Renal Function from Series That Reported the Results of Percutaneous Nephrolithotomy in Patients with Impaired Renal Function

			Renal function at the end of follow-up
Series	Number of patients	Follow-up time	ESRD, n (%)	IRF, n (%)	NRF, n (%)
Gupta and coworkers¹	13	4–5 years	4 (31)	9 (69)	—
Kukreja and coworkers²	84	2.20 ± 1.34 years	12 (14)	39 (47)	33 (39)
Agrawal and coworkers³	78	1.5–9 years	—	11 (14)	64 (82)
Jones and coworkers¹⁶	14	4–29 months	1 (7)	11 (79)	2 (14)
Present study	16	51.1 ± 10.1 month	4 (25)	6 (37.5)	6 (37.5)

ESRD = end-stage renal disease; IRF = impaired renal function; NRF = normal renal function.

It has been reported by Gupta and coworkers¹ that multiple procedures may be needed for the treatment of urinary calculi in patients with renal insufficiency. We wanted to identify the stone recurrence rates and risk factors for recurrence in this group of patients. We had two patients (12.5%) with multiple recurrences in IRF group. This result is similar to the rate (15%) that we detected in NRF group. One of these patients in the IRF group had hypercalciuria and had multiple recurrences in both kidneys despite medical prophylaxis and underwent multiple additional procedures. The other patient had infection stones and she also had multiple recurrences in the opposite kidney. These findings indicate that patients with IRF who also have metabolic abnormalities or infection stones might be at higher risk for stone recurrence in a long-term follow-up and it would be better to monitor closely for recurrence after surgery.

Conclusions

Our results indicate that most patients presenting with kidney stone disease and renal insufficiency experience improvement or stabilization of renal function after removal of stones with PCNL. The patients with solitary kidney and those with conditions such as diabetes and atherosclerosis might be at greater risk for the deterioration of renal function despite stone clearance and the relief of obstruction. However, further investigations with a larger series are needed. We expect that our study will form a base step for future investigations.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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