Progression of nephrolithiasis: long-term outcomes with observation of asymptomatic calculi

BACKGROUND AND PURPOSE: Observation is often recommended for patients presenting with asymptomatic renal calculi. This study evaluated the natural history of asymptomatic calculi and the risk of progression of disease. PATIENTS AND METHODS: We conducted a retrospective evaluation of 300 male patients average age 62.8 years who were followed for a mean of 3.26 years for asymptomatic renal calculi in an outpatient urology clinic. At presentation, the mean cumulative stone diameter was 10.8 mm; 56% were lower-pole stones, and 48% of the patients had multiple calculi. Patients underwent annual radiographic imaging and clinic visits with standardized questions regarding the development of symptoms or complications from calculi. Progression of disease was defined as the need for surgical intervention, the development of pain, or stone growth on serial imaging. RESULTS: Overall, 77% of patients experienced disease progression, with 26% requiring surgical intervention. Stone size was positively associated with progression: those with an isolated stone >/=4 mm on presentation were 26% more likely to fail observation than patients with smaller solitary calculi (P = 0.012). Stone growth was less common in those with upper-pole and middle-pole stones (47% v 61%) for lower-pole stones; P = 0.002). Urine uric acid concentration correlated positively with the rate of stone growth (P = 0.05). Likewise, serum uric acid concentration predicted stone growth (odds ratio = 3.6). CONCLUSIONS: Stratification of risk of progression according to presenting stone size, location, and composition may facilitate discussions with the patient regarding the alternatives of observation versus intervention. Specifically, small non-uric acid calculi in the upper pole may be most amenable to observation.     

Determination of stone composition by noncontrast spiral computed tomography in the clinical setting

OBJECTIVES: Several investigators have evaluated noncontrast computed tomography (NCCT) in predicting stone composition in vitro. We assessed NCCT in predicting stone composition in patients presenting to our emergency room with flank pain and stone disease. METHODS: One hundred twenty-nine patients presenting to our university hospital with flank pain underwent renal colic protocol NCCT scans at the request of the emergency room physicians. A General Electric, high-speed advantage CT scanner was used at 120 kV, 200 mA, and 1.4:1 pitch, with collimation varying between 3 and 5 mm. Ninety-nine patients with predominantly (greater than 50%) calcium oxalate or uric acid composition after either stone passage or stone removal were identified. Each scan was analyzed by one of two radiologists, who determined the predominant attenuation for each stone. Stones once passed or retrieved were analyzed by Urocor Laboratories. The attenuation and attenuation/size ratio (peak attenuation/size in millimeters) were compared with the results of the stone analysis. RESULTS: Eighty-two calculi predominantly composed of calcium oxalate and 17 calculi predominantly composed of uric acid were identified in 99 patients. The calculi ranged in size from 1 to 28 mm. A significant difference (P = 0.017, unpaired t test) was found between the Hounsfield measurement of uric acid calculi (mean 344 +/- 152 HU) and the Hounsfield measurement of calcium oxalate calculi (mean 652 +/- 490 HU). If only the Hounsfield units from stones 4 mm or larger were compared, the data were even more compelling (P = 0.002). However, using an attenuation/size ratio cutoff of greater than 80, the negative predictive value was 99% that a stone would be predominantly calcium oxalate. CONCLUSIONS: Using peak attenuation measurements and the attenuation/size ratio of urinary calculi from NCCT, we were able to differentiate between uric acid and calcium oxalate stones.     

Essential arterial hypertension and stone disease.

BACKGROUND: Cross-sectional studies have shown that nephrolithiasis is more frequently found in hypertensive patients than in normotensive subjects, but the pathogenic link between hypertension and stone disease is still not clear. METHODS: Between 1984 and 1991, we studied the baseline stone risk profile, including supersaturation of lithogenic salts, in 132 patients with stable essential hypertension (diastolic blood pressure of more than 95 mm Hg) without stone disease and 135 normotensive subjects (diastolic blood pressure less than 85 mm Hg) without stone disease who were matched for age and sex (controls). Subsequently, both controls and hypertensives were followed up for at least five years to check on the eventual formation of kidney stones. RESULTS: Baseline urine levels in hypertensive males were different from that of normotensive males with regards to calcium (263 vs. 199 mg/day), magnesium (100 vs. 85 mg/day), uric acid (707 vs. 586 mg/day), and oxalate (34.8 vs. 26.5 mg/day). Moreover, the urine of hypertensive males was more supersaturated for calcium oxalate (8.9 vs. 6.1) and calcium phosphate (1.39 vs. 0.74). Baseline urine levels in hypertensive females were different from that of normotensive females with regards to calcium (212 vs. 154 mg/day), phosphorus (696 vs. 614 mg/day), and oxalate (26.2 vs. 21.7 mg/day), and the urine of hypertensive females was more supersaturated for calcium oxalate (7.1 vs. 4.8). These urinary alterations were only partially dependent on the greater body mass index in hypertensive patients. During the follow-up, 19 out of 132 hypertensive patients and 4 out of 135 normotensive patients had stone episodes (14.3 vs. 2.9%, chi-square 11.07, P = 0.001; odds ratio 5.5, 95% CI, 1.82 to 16.66). Of the 19 stone-former hypertensive patients, 12 formed calcium calculi, 5 formed uric acid calculi, and 2 formed nondetermined calculi. Of the urinary factors for lithogenous risk, those with the greatest predictive value were supersaturation of calcium oxalate for calcium calculi and uric acid supersaturation for uric acid calculi. CONCLUSIONS: A significant percentage of hypertensive subjects has a greater risk of renal stone formation, especially when hypertension is associated with excessive body weight. Higher oxaluria and calciuria as well as supersaturation of calcium oxalate and uric acid appear to be the most important factors. Excessive weight and consumption of salt and animal proteins may also play an important role.     

Effect of potassium citrate therapy on stone recurrence and residual fragments after shockwave lithotripsy in lower caliceal calcium oxalate urolithiasis: a randomized controlled trial

BACKGROUND AND PURPOSE: To evaluate the efficacy of potassium citrate treatment in preventing stone recurrences and residual fragments after shockwave lithotripsy (SWL) for lower pole calcium oxalate urolithiasis. PATIENTS AND METHODS: One hundred ten patients who underwent SWL because of lower caliceal stones and who were stone free or who had residual stone 4 weeks later were enrolled in the study. The average patient age was 41.7 years. All patients had documented simple calcium oxalate lithiasis without urinary tract infection and with normal renal morphology and function. Four weeks after SWL, patients who were stone free (N = 56) and patients who had residual stones (N = 34) were independently randomized into two subgroups that were matched for sex, age, and urinary values of citrate, calcium, and uric acid. One group was given oral potassium citrate 60 mEq per day, and the other group served as controls. RESULTS: In patients who were stone free after SWL and receiving medical treatment, the stone recurrence rate at 12 months was 0 whereas untreated patients showed a 28.5% stone recurrence rate (P < 0.05). Similarly, in the residual fragment group, the medically treated patients had a significantly greater remission rate than the untreated patients (44.5 v 12.5%; P < 0.05). CONCLUSION: Potassium citrate therapy significantly alleviated calcium oxalate stone activity after SWL for lower pole stones in patients who were stone free. An important observation was the beneficial effect of medical treatment on stone activity after SWL among patients with residual calculi.     

Effect of holmium:YAG laser pulse width on lithotripsy retropulsion in vitro

BACKGROUND AND PURPOSE: The effect of laser pulse width on calculus retropulsion during ureteroscopic lithotripsy is poorly defined because of the limited availability of variable pulse-width lasers. We used an adjustable pulse-width Ho:YAG laser to test the effect of pulse width on in vitro phantom-stone retropulsion and fragmentation efficiency. METHODS AND MATERIALS: An Odyssey 30 Ho:YAG laser (Convergent Laser Technologies, Oakland, CA) with adjustable pulse width (350 or 700 microsec) was used to treat spherical 10-mm plaster calculi in a model ureter (N = 40) and calix (N = 16) utilizing 200- and 400-microm fibers (10 Hz, 1.0 J). Calculi were placed in a waterfilled clear polymer tube, and laser energy was applied continuously in near contact until the stone had moved 8 cm. The time (seconds) and energy (joules) needed to cause the stone to traverse this distance was recorded. Stones were also placed in a stainless-steel mesh calix model in which retropulsion was limited. Laser energy was applied for 5 minutes at each pulse width. A laser-energy meter (Molectron Detector Inc, Portland OR) was used to quantify fiber transmission efficiency after 1 minute of continuous lithotripsy for each fiber at each pulse width. RESULTS: Retropulsion was greater for stones treated at 350 microsec, indicated by a shorter time to traverse the model ureter. For the 200-microrm fiber at 350 microrsec, the average time was 11.5 seconds v 20.3 seconds at 700 microsec (P < 0.001). The average total energy delivered was 114.9 J at 350 microsec v 199.8 J at 700 microsec (P < 0.001). For the 400-microm fiber at 350 microsec, the average time was 5.8 seconds v 11.9 seconds at 700 microsec (P < 0.001). The average total energy was 57.1 J at 350 microsec v 127.3 J at 700 microsec (P < 0.001). In the caliceal model, at 350 and 700 microsec with the 200- and 400-microm fibers, mass loss was 34.9% and 33.4% (P = 0.8) and 14.6% and 21.6% (P = 0.04), respectively. The reduction in energy transmission at 350 microsec and 700 microsec with the 200- microm fiber after 60 seconds of continuous lasing was 8.82% v 9%, respectively (P = 0.95). For the 400-microm fiber, the transmission loss was 18.4% at 350 microsec v 4.4% at 700 microsec (P = 0.0002). CONCLUSION: When treating ureteral calculi, retropulsion can be reduced by using a longer pulse width without compromising fragmentation efficiency. For caliceal calculi, the longer pulse width in combination with a 400-microm fiber provides more effective stone fragmentation.     

Ureteroscopic management of lower-pole stones in a pediatric population

PURPOSE: We report our experience with ureteroscopy to treat lower-pole calculi in children. PATIENTS AND METHODS: A retrospective review was conducted of all ureteroscopic procedures for lower-pole stone disease at a pediatric institution from 2000 through 2005. A total of 13 girls and 8 boys with a mean age of 15 years (range 1-20 years) underwent flexible ureteroscopy for lower-pole calculi. The mean stone burden was 12 mm. Stone-free status was defined by postoperative abdominal radiography, CT, or ultrasonography. RESULTS: Ureteral stenting was performed preoperatively in 38% and postoperatively in 71% of the patients. Ureteral-access sheaths were placed in 43%. There were no intraoperative or postoperative complications. With a mean follow-up of 11 months, 76% of the children were stone-free. The success rate for stones <15 mm was 93% v 33% for stones > or =15 mm (P = 0.01). CONCLUSION: Ureteroscopy and laser lithotripsy are safe and effective in children with lower-pole calculi. Ureteroscopy can be considered a primary treatment option for children with lower-pole calculi <15 mm.     

Prediction of calcium level in melamine-related urinary calculi with helical CT: diagnostic performance evaluation and clinical significance

The aim of the study was to investigate the relationship between CT-attenuation and stone calcium level in melamine-related urinary calculi (MRUC). A total of 25 MRUC with known composition and calcium level were included (11 uric acid stones, 2 calcium oxalate stones and 12 mixture stones of uric acid and calcium oxalate). Of all, 18 renal stones accepted alkalization therapy except for 5 lower urinary tract stones and 2 stones of unknown position. With well-matched composition, 61 adult urinary stones were included as controls. Every stone was scanned by helical CT (80 kV/120 kV, 300 mA, pitch 0.625 mm) and the highest CT-attenuation value measured. CT-attenuation values of MRUC increased gradually from uric acid stones, mixture stones to calcium oxalate stones, but were always lower than the values of controls. Furthermore, a strong positive correlation was found between stone CT-attenuation value and stone calcium level (n = 25, r (80kV) = 0.883, p = 0.000; r (120kV) = 0.855, p = 0.000). Compared with alkalization-therapy-alone group, stone CT-attenuation values and stone calcium level in the comprehensive-therapy group were significantly greater (CT(80kV) 1,057 ± 639 vs. 172 ± 61 HU, p = 0.001; CT(120kV) 783 ± 476 vs. 162 ± 60 HU, p = 0.001; Ca 19.83 ± 7.48% vs. 1.30 ± 1.51%, p = 0.000). Fisher's exact test suggested that the stones with higher CT-attenuation values tended to resist alkalization when 400 HU served as the cutoff value (P (80kV) = 0.002, P (120kV) = 0.000). In conclusion, the study was the first to illustrate that the CT-attenuation value could reflect calcium level in MRUC and found that stones with higher CT-attenuation value were not amenable to alkalization because they probably contained greater calcium. For those patients, we believe that comprehensive therapy will be the best choice.     

Percutaneous nephrolithotomy for complete staghorn calculi in preschool children

BACKGROUND AND PURPOSE: To evaluate the safety and efficacy of percutaneous nephrolithotomy (PCNL) for the management of complete staghorn calculi in children 相似文献   

The impact of cystinuria on renal function

PURPOSE: Patients with cystinuria frequently have recurrent renal calculi and may subsequently require multiple stone removing procedures during their lifetime which could have an impact on overall renal function. We determined the potential impact of cystinuria and cystine stone formation on the level of renal function compared to calcium oxalate stone formers. MATERIALS AND METHODS: Clinical data on 40 cystinuric patients followed at 2 medical centers and 45 such individuals in a large stone population data base were analyzed. These results were compared to data on 3,964 calcium oxalate stone formers enrolled in this data base. RESULTS: Mean serum creatinine plus or minus standard deviation for stone forming cystinuric patients was significantly higher than that of the calcium oxalate cohort (1.13 +/- 0.28 versus 1.01 +/- 0.28 mg./100 ml., p = 0.0001). A significantly greater percentage of cystinuric patients (5.8%) had an abnormally increased serum creatinine compared to the calcium oxalate stone formers (2.2%, p = 0.046). Male gender, increasing number of open surgical stone removing procedures and nephrectomy were significant variables associated with an increased serum creatinine (p = 0.0010, p = 0.0038, p = 0.0133, respectively). An increasing number of open surgical stone removing procedures had a significant positive correlation with performance of nephrectomy in the cystinuric population (p = 0.0166). A significantly greater percentage of cystinuric patients compared to the calcium oxalate cohort were subjected to nephrectomy (14.1% versus 2.9%, p = 0.007). CONCLUSIONS: Cystinuric patients have higher serum creatinine levels than calcium oxalate stone formers and they are at more risk for renal loss. When stone removal is required, a minimally invasive approach is preferred.     

Pharmacologic treatment of uric acid calculi

Uric acid stone disease is dependent on three pathogenetic factors: acid urine pH, low urine volume, and hyperuricosuria. The management of nonobstructing uric acid calculi should include maintenance of an alkaline urine, an increase in urine volume, and reduction in urinary uric acid excretion. It appears that potassium alkali may avoid the complication of calcium stone formation in patients with uric acid stones. In patients with obstructing uric acid calculi, more rapid dissolution may be accomplished with intravenous alkalinization or direct irrigation of the stone with an alkaline solution.     

Ureteroscopic versus percutaneous treatment for medium-size (1-2-cm) renal calculi

PURPOSE: To compare the outcomes of percutaneous nephrolithotomy (PCNL) and ureterorenoscopy (URS) for 1- to 2-cm renal calculi with specific reference to the stone clearance rate and morbidity. PATIENTS AND METHODS: The records of 27 patients who underwent either PCNL (N = 15) or URS (N = 12) by standard techniques over an 8-month period for renal calculi between 1 and 2 cm were reviewed retrospectively. Demographic, intraoperative, and postoperative data were accrued and compared to identify any statistically significant differences. The median stone burden was slightly but not significantly higher in the PCNL group (1.8 cm v 1.25 cm; P = 0.19). Postoperative plain films were used to confirm stone clearance. RESULTS: The procedure was technically successful in all 27 patients. No patient in either group required a repeat session or ancillary procedure. All 15 PCNL procedures were completed through a single percutaneous tract. The PCNL and URS groups were equivalent with respect to operative time (79.0 minutes v 68.5 minutes) and incidence of complications (2 v 0). No patient in either group had significant hemorrhage or required blood transfusion. The overall stone-free rate was 87% for PCNL and 67% for URS (P = 0.36). CONCLUSIONS: Both PCNL and URS are effective options for renal calculi between 1 and 2 cm. The stonefree and complication rates for PCNL are higher, but the differences were not statistically significant in our series. The operative times are statistically equivalent, despite the potentially longer fragmentation times required for URS. The choice of treatment ultimately depends on the individual surgeon's preference and level of expertise.     

Comparison of intraoperative parameters and perioperative complications of retroperitoneal and transperitoneal approaches to laparoscopic partial nephrectomy: support for a retroperitoneal approach in selected patients

BACKGROUND AND PURPOSE: Retroperitoneal laparoscopy (RP) may have some intrinsic advantages over transperitoneal laparoscopy (TP) in certain patients undergoing partial nephrectomy. We reviewed our experience with RP and TP partial nephrectomy to identify differences in intraoperative and postoperative parameters. PATIENTS AND METHODS: The records of 72 patients (45 TP, 27 RP) undergoing laparoscopic partial nephrectomy without hand assistance between January 2003 and August 2005 were reviewed. The two groups were similar demographically; tumors were smaller in RP patients (2.1 v 2.7 cm; P = 0.03), and the RP approach was used more frequently on right kidneys (70.4% v 37.8%; P = 0.01). RESULTS: The operative time (mean 160 v 192 minutes; P = 0.008) and length of stay (LOS; median 1.0 days [range 1-10 days] v 2.0 days [range 1-64 days]; P = 0.001) were shorter in RP patients. Rates of collecting system entry (22% v 38%), positive-margin rate (0% v 6.7%; P = 0.29), and complications (19% v 22%; P = 0.77) were similar in RP and TP patients. Hemorrhage was the most common complication in both groups. Bowel-related complications occurred in three TP patients, but in no RP patients. Overall, the median estimated blood loss (EBL) was lower in RP patients (100 mL [range 25-3500 mL] v 225 mL [range 25-1900 mL]; P = 0.06). Among patients with complications, EBL was similar in both groups (median 325 mL [50-1500 mL] v 200 mL [50-3500 mL] for RP and TP; P = 0.86). CONCLUSIONS: The RP approach reduces operative time, LOS, and some types of complications without compromising the quality of tumor resection. Complications in the retroperitoneal space are not associated with higher EBL. Anatomic considerations and surgeon experience may improve outcomes.     

Pneumatic lithotripsy versus laser lithotripsy in the endoscopic treatment of ureteral calculi

PURPOSE: To compare the efficacy, safety, and features of pneumatic lithotripsy (PL) with those of laser lithotripsy (LL) and present our clinical experience in the endoscopic management of ureteral calculi. PATIENTS AND METHODS: From August 1994 to February 2000, 285 consecutive patients underwent endoscopic lithotripsy with either the Swiss Lithoclast pneumatic lithotripter (145 patients) or the Ho:YAG laser lithotripter (140 patients) for the treatment of ureteral calculi. RESULTS: In one single session, the overall successful stone fragmentation rate of LL was higher than that of PL (95.7% v 69.7%; P < 0.01). The average time to stone-free status was shorter for LL than for PL (18 days v 31 days; P < 0.01). No major complications were observed in LL, while five ureteral perforations were encountered in PL. CONCLUSIONS: Laser lithotripsy has advantages over PL in high efficiency of stone fragmentation and a low complication rate. Laser lithotripsy is a powerful, effective, and safe treatment modality for ureteral calculi.     

Laparoscopic versus open cytoreductive nephrectomy in advanced renal-cell carcinoma

BACKGROUND AND PURPOSE: There is growing evidence of the benefit of cytoreductive nephrectomy prior to immunotherapy in patients with advanced renal-cell carcinoma (RCC). We compared the outcomes of patients with metastatic RCC undergoing laparoscopic and open cytoreductive nephrectomy prior to systemic therapy. PATIENTS AND METHODS: We retrospectively analyzed 27 patients undergoing cytoreductive nephrectomy for metastatic RCC between 2000 and 2004, 16 laparoscopically and 11 by an open approach. Patients with inferior vena-caval tumor thrombus were excluded from analysis. The two groups were comparable with regard to tumor size, clinical stage, and performance status. Surgical, pathologic, and perioperative characteristics and outcomes were compared. RESULTS: The laparoscopic technique was associated with reduced blood loss (149 v 1135 mL; P = 0.03), transfusion rate and quantity (13% v 55%; P = 0.03; 0.13 v 2.0 units of packed red blood cells; P = 0.007), shorter time to oral intake (1.2 v 2.7 days; P < 0.001), and shorter hospitalization (3.6 v 6.8 days; P < 0.001) compared with open nephrectomy. No significant differences were observed with respect to pathologic stage, operative time, complications, fraction receiving subsequent systemic therapy, time to systemic therapy, or survival. CONCLUSIONS: Laparoscopic cytoreductive nephrectomy is associated with reduced morbidity and hospital stay compared with open surgery. There was no increase in complications, and the ability to proceed with subsequent systemic therapy was maintained in the majority of patients. The laparoscopic approach can be considered in patients with metastatic RCC as part of a cytoreductive and systemic-therapy regimen.     

Impact of shockwave coupling on efficacy of extracorporeal shockwave lithotripsy

PURPOSE: To evaluate the impact of a slow gated treatment rate on the efficacy of extracorporeal shockwave lithotripsy (SWL). PATIENTS AND METHODS: From August 1990 to July 2002, 40,462 SWL procedures were performed using the slow frequency electrocardiography (ECG)-gated lithotripter (82.5%) and fast frequency ECG-ungated (17.5%) modes for the Medstone STS lithotripter. Treatment characteristics, including the mode of SWL, location and size of the stone, re-treatment status, auxiliary procedures required, perioperative complications, and treatment outcomes, were recorded. The stone-free rate was reported by the treating physician on the basis of the finding of no residual stone fragments on a plain radiographic image. RESULTS: The treatment rate for the slow mode was a mean of 79.6 shocks/min, while the rate for the fast mode was 120/min. The total procedure time was 47.0 minutes for the slow mode and 40.6 minutes for the fast. The overall stone-free rate was higher for slow (66.9%) than fast (63.6%) procedures (P < 0.001). The stone-free rate for 1- to 10-mm stones was higher for the slow procedures (75.7%) than the fast procedures (70.7%; P < 0.001). Upper-ureteral stones responded better to slow treatment in terms of stone-free rate (79.5% v 72.6%; P < 0.001), re-treatment rate (6.5% v 8.0%, P = 0.05), auxiliary-procedure rate (6.1% v 8.9%; P = 0.01), and efficiency quotient (71 and 62). There was no significant difference in complication rates overall between slow and fast treatment. CONCLUSIONS: With a minimal increase in procedure time, greater efficacy can be obtained for the treatment of radiopaque stones with a slower shock-delivery rate. In particular, upper-ureteral calculi and calculi <10 mm benefit from a slower treatment rate.     

Percutaneous nephrolithotomy in patients aged 60 years or older

PURPOSE: To assess the safety and efficacy of percutaneous nephrolithotomy in patients more than 60 years old. PATIENTS AND METHODS: We retrospectively evaluated and compared the data of 28 percutaneous nephrolithotomies (PCNL) performed on 27 patients aged 60 years and older (mean 65.8) with the data of the remaining 178 PCNL procedures on 166 patients performed in our clinic between December 1997 and December 1999. RESULTS: Although staghorn stones seemed to be more common in the elderly group (25% v 22%), no statistical significance was demonstrated (P = 0.715), and the stone burden was similar for the two groups (P = 0.112). The only interesting finding in terms of patient characteristics was a significantly higher incidence of solitary kidney in patients aged 60 years or older (29% v 7%; P = 0.003). The success rates (stone-free patients and patients with residual stones <4 mm) were similar, being 89% for the elderly group and 92% for the younger patients (P = 0.718). Transfusion rates were also similar (21.4% in the elderly v 18% in the younger group; P = 0.662). No significant complication was observed in this elderly group, and no renal deterioration has been detected even in the follow-up of patients with a solitary kidney. CONCLUSIONS: Despite the somewhat higher stone burden in the elderly patients (1077.92 mm2 v 920.85 mm2), the stone-free rate was similar to that obtained in the younger patients, without any higher rates of complications or blood transfusions or longer hospital stay. Percutaneous nephrolithotomy is a safe and effective method of stone treatment in the elderly, even if they have a solitary kidney or complex calculi.     

Excretion of tamm-horsfall protein in patients with uric acid stones.

The cause of reduced Tamm-Horsfall protein excretion in patients suffering from uric acid diathesis is still unknown. Our investigation was conducted based on the hypothesis that the solubility of uric acid is increased by Tamm-Horsfall protein and that an increased uric acid content in the urine might cause a decrease in Tamm-Horsfall protein. In 20 patients with uric calculi the excretion of Tamm-Horsfall protein, uric acid, calcium, and citrate was measured. 65% of the patients had pure uric acid stones (group I) and 35% showed mixed stones with at least 30% of uric acid (group II). Reduced Tamm-Horsfall protein excretion was found in 63% of the patients of group I and in 43% of the patients of group II. The excretion of Tamm-Horsfall protein was significantly reduced in pure uric acid stone formers compared to normal subjects (p < 0. 0001). The excretion of uric acid was elevated in 61% of the patients of group I and in 86% of the patients of group II. There was no significant correlation between Tamm-Horsfall protein excretion and uric acid excretion (r = 0.2139). Calcium excretion was elevated in 57% of the patients with mixed stones. The excretion of citrate was reduced in almost all of the patients of groups I and II. Our results do not support the hypothesis that an increased content of uric acid in the urine causes a decrease in Tamm-Horsfall protein. In our opinion the lower excretion of Tamm-Horsfall protein in some of the stone patients might be caused by damage in the distal tubular epithelium. Moreover, it has to be supposed that there are defects both in the distal and the proximal tubule in patients prone to develop uric acid calculi.     

Changing gender prevalence of stone disease

PURPOSE: Recent studies suggest that the incidence of renal stone formation has been increasing and the male predominance of nephrolithiasis is decreasing, which may be due to changes in diet and lifestyle. We examined changes in the prevalence by gender of inpatient hospital discharges for urinary stone disease. MATERIALS AND METHODS: The Nationwide Inpatient Sample was used for analysis. Discharges with an International Classification of Diseases, 9th revision, Clinical Modification principal diagnosis of 592.0 (calculus of kidney) or 592.1 (calculus of ureter) from 1997 to 2002 were included in the investigation. RESULTS: An estimated mean+/-SE 1,013,621+/-19,310 discharges for stone disease occurred from 1997 to 2002. Discharges for renal calculus increased by 18.9% during the study period (p<0.001), while discharges for ureteral calculus remained relatively constant. After adjusting for population changes discharges for renal calculi increased by 14.2% (p=0.002). In females discharges for renal calculi increased by 21.0% and discharges for ureteral calculi increased by 19.2% (each p<0.001). After adjusting for population changes renal calculus and ureteral calculus discharges in females increased by 22.0% (p=0.001) and 14.5% (p=0.005), respectively. CONCLUSIONS: In this nationally representative sample the population adjusted rate of discharges for stone disease in females dramatically increased from 1997 to 2002. This alteration represents a change in the prevalence by gender of treated stone disease from a 1.7:1 to 1.3:1 male-to-female ratio. It may reflect variations in the underlying prevalence by gender of stone disease. We speculate that the increasing incidence of nephrolithiasis might be due to lifestyle associated risk factors, such as obesity.     

Association of vitamin D receptor-gene (FokI) polymorphism with calcium oxalate nephrolithiasis

BACKGROUND AND PURPOSE: Formation of kidney stones is still not understood but is hypothesized to be associated with the vitamin D receptor gene (VDR). In order to assess the eventual role of VDR start-codon FokI polymorphism in stone formation, we evaluated the association between calcium stone disease and this polymorphism in a North Indian population. PATIENTS AND METHODS: A control group comprised of 166 healthy individuals (age range 22-58 years) and a group of 138 patients with calcium oxalate stones (age range 21-72 years) were examined. The polymorphism was detected using polymerase chain reaction-based restriction analysis. An unexcisable length of 265 bp (CC) and two fragments of 169 bp and 96 bp (TT) were obtained by FokI restriction digestion. RESULTS: There was a statistically significant difference between the control and patient groups (X2 test, P<0.001) for the genotype of the VDR FokI start-codon polymorphism. The odds ratio (with 95% CI) for the C allele in those at risk of stone disease was 1.654 (1.041, 2.628). The VDR frequency distribution was also statistically significant (P<0.001) in case of male sex. The frequency distribution for this genetic polymorphism was not statistically different in normocalciuric and hypercalciuric stone patients (P=0.355). CONCLUSION: The VDR FokI polymorphism may be a good candidate for a marker for calcium oxalate-stone disease. These findings may contribute a small piece to the understanding of the pathogenesis of urinary calculi.     

Characteristics of patients with staghorn calculi in our experience

PURPOSE: To elucidate the factors contributing to staghorn stone formation in patients. MATERIALS AND METHODS: The records of 82 patients (44 men and 38 women) with complete staghorn calculi were reviewed retrospectively for clinical presentation, metabolic disturbances and anatomical abnormalities. RESULTS: There were 79 unilateral and three bilateral cases. The patient performance of the activities of daily life was assessed with the modified Rankin scale (MRS) and it was found that 69 patients were functionally independent (84.1%, MRS 0-1) and 10 patients had a severe disability (12.2%, MRS 4-5). Seven patients had chronic indwelling catheters (8.5%). A positive urine culture was found in 24.4% of patients. Analysis of stone composition revealed magnesium ammonium phosphate and mixed calcium oxalate-phosphate were the most frequently identified types of stone (32.1% and 22.2%, respectively). Urinary pH was low in patients with uric acid stones (mean 5.4). Hyperuricemia, cystinuria and hypercalciuria were found in 14.6%, 2.4% and 37.8%, respectively. Hypercalciuria was found more frequently in calcium-stone cases. Eleven patients (13.4%) showed structural abnormalities of the kidney. CONCLUSIONS: Our data show that the patients with severe disability, urinary tract infection and hypercalciuria could be recognized more frequently in staghorn calculi compared with common urolithiasis. However, in Western countries, the frequency of both urinary tract infection and struvite stones is much higher than in our data. Other Japanese authors have also reported the low frequency of struvite stones in staghorn calculi, suggesting that various factors other than urinary tract infection possibly contribute to the formation of staghorn calculi in Japan.