Metformin ameliorates calcium oxalate crystallization and stone formation by activating the Nrf2/HO-1 signaling pathway: Two birds with one stone.

Deposition of calcium oxalate (CaOx) crystals and oxidative stress-induced injury of renal tubular epithelial cell are the primary pathogenic factors of nephrolithiasis. In this study we investigated the beneficial effects of metformin hydrochloride (MH) against nephrolithiasis and explored the underlying molecular mechanism. Our results demonstrated that MH inhibited the formation of CaOx crystals and promoted the transformation of thermodynamically stable CaOx monohydrate (COM) to more unstable CaOx dihydrate (COD). MH treatment effectively ameliorated oxalate-induced oxidative injury and mitochondrial damage in renal tubular cells and reduced CaOx crystal deposition in rat kidneys. MH also attenuated oxidative stress by lowering MDA level and enhancing SOD activity in HK-2 and NRK-52E cells and in a rat model of nephrolithiasis. In both HK-2 and NRK-52E cells, COM exposure significantlylowered the expressions of HO-1 and Nrf2, which was rescued by MH treatment even in the presence of Nrf2 and HO-1 inhibitors. In rats with nephrolithiasis, MH treatment significantly rescued the down-regulation of the mRNA and protein expression of Nrf2 and HO-1 in the kidneys. These results demonstrate that MH can alleviate CaOx crystal deposition and kidney tissue injury in rats with nephrolithiasis by suppressing oxidative stress and activating the Nrf2/HO-1 signaling pathway, suggesting the potential value of MH in the treatment of nephrolithiasis.

Cost-effectiveness of Retrograde Intrarenal Surgery, Standard and Mini Percutaneous Nephrolithotomy, and Shock Wave Lithotripsy for the Management of 1-2cm Renal Stones.

OBJECTIVE: To perform a cost-effectiveness evaluation comparing the management options for mid-size (1-2cm) renal stones including percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery (RIRS), and shockwave lithotripsy (SWL). METHODS: A Markov model was created to compare cost-effectiveness of PCNL, mini-PCNL, RIRS, and SWL for 1-2cm lower pole (index patient 1) and PCNL, RIRS, and SWL for 1-2 cm non-lower pole (index patient 2) renal stones. A literature review provided stone free, complication, retreatment, secondary procedure rates, and quality adjusted life years (QALYs). Medicare costs were used. The incremental cost-effectiveness ratio (ICER) was compared with a willingness-to-pay(WTP) threshold of $100,000/QALY. One-way and probabilistic sensitivity analyses were performed. RESULTS: At 3 years, costs for index patient 1 were $10,290(PCNL), $10,109(mini-PCNL), $5,930(RIRS), and $10,916(SWL). Mini-PCNL resulted in the highest QALYs(2.953) followed by PCNL(2.951), RIRS(2.946), and SWL(2.943). This translated to RIRS being most cost-effective followed by mini-PCNL(ICER $624,075/QALY) and PCNL(ICER $946,464/QALY). SWL was dominated with higher costs and lower effectiveness. For index patient 2, RIRS dominated both PCNL and SWL. For index patient 1: mini-PCNL and PCNL became cost effective if cost ≤$5,940 and ≤$5,390, respectively. SWL became cost-effective with SFR ≥75% or cost ≤$1,236. On probabilistic sensitivity analysis, the most cost-effective strategy was RIRS in 97%, mini-PCNL in 2%, PCNL in 1%, and SWL in 0% of simulations. CONCLUSION: For 1-2cm renal stones, RIRS is most cost-effective. However, mini and standard PCNL could become cost-effective at lower costs, particularly for lower pole stones.

Comparing extracorporeal shock wave lithotripsy and ureteroscopy laser lithotripsy for treatment of urinary stones smaller than 2 cm: a cost-utility analysis in the Spanish clinical setting.

PURPOSE: To analyze the efficiency and cost-utility profile of ureteroscopy versus shock wave lithotripsy for treatment of reno-ureteral stones smaller than 2 cm. METHODS: Patients treated for urinary stones smaller than 2 cm were included in this study (n = 750) and divided into two groups based on technique of treatment. To assess the cost-utility profile a sample of 48 patients (50% of each group) was evaluated. Quality of life survey (Euroqol 5QD-3L) before-after treatment was applied, Markov model was designed to calculate quality of life in each status of the patients (stone or stone-free with and without double-J stent) and to estimate the incremental cost-utility. Monte carlo simulation was conducted for a probabilistic sensitivity analysis. Chi-square was used for comparing qualitative variables and T student's for continuous variables. RESULTS: Shock wave lithotripsy group had 408 (54.4%) and ureteroscopy group had 342 (45.6%) patients. Of them, 56.3% were treated for renal stones and 43.7% for ureteral stones. Ureteroscopy produced slightly higher overall quality of patients' life, but produced a significant higher overall cost per quality-adjusted life year (QALY) than shock wave lithotripsy, exceeding the cost-utility threshold (20,000€/QALY). Sensitivity analysis confirmed results in 93.65% of cases. Difference was maintained in subgroup analysis (ureteral vs renal stones). CONCLUSIONS: Results suggest that in our clinical setting shock wave lithotripsy has better cost-utility profile than ureteroscopy for treatment of reno-ureteral stones less than 2 cm, but excluding waiting times, in ideal clinical setting, ureteroscopy would have better cost-utility profile than shock wave lithotripsy.

Clinical Assessment of Risk Factors for Renal Atrophy After Percutaneous Nephrolithotomy.

BACKGROUND This study explored the risk factors for renal atrophy after percutaneous nephrolithotomy (PCNL), and provides a reference for clinical prevention of renal atrophy after PCNL. MATERIAL AND METHODS According to the inclusion and exclusion criteria, the clinical data of 816 patients who underwent PCNL in our hospital from May 2013 to February 2018 were retrospectively collected. Depending on whether the patient had kidney atrophy, they were divided into a renal atrophy group and a non-renal atrophy group. We collected and analyzed data on patient sex, age, kidney location, duration of disease, stone size, hydronephrosis, renal calculus position (renal ureteral junction or multiple pyelonephritis-associated stones), operation time, intraoperative blood loss, perfusion pressure, and pyonephrosis. The indicators with statistically significant differences were selected and multivariate logistic regression analysis was carried out to determine the risk factors for renal atrophy. RESULTS Among 816 patients, 49 had renal atrophy and the incidence rate was 6.01%. Univariate analysis and multivariate logistic regression analysis showed that independent risk factors for renal atrophy after PCNL were: duration of the disease longer than 12 months (OR=4.216, P=0.003, 95% CI: 1.714, 7.354), perfusion pressure >30 mmHg (OR=3.895, P=0.001, 95% CI: 1.685, 8.912), moderate and severe hydronephrosis (OR=5.122, P<0.001, 95% CI: 1.847, 9.863), stones located at the junction of the renal pelvis (OR=3.787, P=0.001, 95% CI: 1.462, 7.654), stones located in multiple calyces (OR=4.531, P=0.014, 95% CI: 1.764, 8.196), and pyonephrosis (OR=10.143, P<0.001, 95% CI: 2.214, 16.248). CONCLUSIONS The main risk factors for renal atrophy after PCNL are: course of disease more than 12 months, moderate and severe hydronephrosis, pyonephrosis, multiple calyceal stones, stones at the junction of the renal pelvis, and intraoperative high perfusion pressure.

A prospective, matched comparison of ultra-low and standard-dose computed tomography for assessment of renal colic.

OBJECTIVE: To determine the diagnostic accuracy of ultra-low-dose computed tomography (ULDCT) compared with standard-dose CT (SDCT) in the evaluation of patients with clinically suspected renal colic, in addition to secondary features (hydroureteronephrosis, perinephric stranding) and additional pathological entities (renal masses). PATIENTS AND METHODS: A prospective, comparative cohort study was conducted amongst patients presenting to the emergency department with signs and symptoms suggestive of renal or ureteric colic. Patients underwent both SDCT and ULDCT. Single-blinded review of the image sets was performed independently by three board-certified radiologists. RESULTS: Among 21 patients, the effective radiation dose was lower for ULDCT [mean (SD) 1.02 (0.16) mSv] than SDCT [mean (SD) 4.97 (2.02) mSv]. Renal and/or ureteric calculi were detected in 57.1% (12/21) of patients. There were no significant differences in calculus detection and size estimation between ULDCT and SDCT. A higher concordance was observed for ureteric calculi (75%) than renal calculi (38%), mostly due to greater detection of calculi of <3 mm by SDCT. Clinically significant calculi (≥3 mm) were detected by ULDCT with high specificity (97.6%) and sensitivity (100%) compared to overall detection (specificity 91.2%, sensitivity 58.8%). ULDCT and SDCT were highly concordant for detection of secondary features, while ULDCT detected less renal cysts of <2 cm. Inter-observer agreement for the ureteric calculi detection was 93.9% for SDCT and 87.8% for ULDCT. CONCLUSION: ULDCT performed similarly to SDCT for calculus detection and size estimation with reduced radiation exposure. Based on this and other studies, ULDCT should be considered as the first-line modality for evaluation of renal colic in routine practice.

Are Routine Laboratory Investigations Necessary Following Percutaneous Nephrolithotomy?

OBJECTIVE: To determine how effective routine postoperative blood work is in identifying complications after percutaneous nephrolithotomy (PCNL), the gold standard treatment for large volume stone disease. Although major complication rates are low, hemorrhagic and sepsis-related complications are serious and can occur. Routine post-PCNL complete blood count is routinely performed by most endourologists but may be a low-value practice. METHODS: A retrospective review was performed of all PCNL procedures at our center over a 3-year period. Patient demographic, stone characteristics and postoperative data were collected and analyzed. RESULTS: Three hundred and eighty-five patients (196 female and 189 males) underwent PCNL for the treatment of urolithiasis. Mean age was 55.8 years and mean length of stay in hospital was 1.74 days. Most patients (82.9%) had neither ureteric stent nor percutaneous tube prior to PCNL. Postoperatively, 4 patients (1.0%) required a blood transfusion and 14 patients (3.6%) developed urosepsis. Patients who required either a transfusion or developed urosepsis demonstrated abnormal vital signs (tachycardia, hypotension, or fever) postoperatively. Sixteen patients (4.2%) had normal vital signs but had an extended hospital stay only to monitor abnormal blood work results. None these patients required a transfusion nor developed urosepsis but had a length of stay that was a mean of 1.5 days longer patients with normal postoperative vital signs and blood work. CONCLUSION: Abnormal vital signs alone identified all patients that required transfusion or treatment for urosepsis after PCNL. Routine complete blood count testing postoperatively may not improve detection of infectious or bleeding complications and may prolong hospital admission unnecessarily.

Percutaneous nephrolithotomy versus flexible ureteroscopy in terms of cost-effectiveness in patients with 10-30 mm renal stones.

PURPOSE: Kidney stones are one of the most common urological problems. When deciding on the method of treatment for this common disease, the cost of the procedure should also be taken into consideration. MATERIALS AND METHODS: We performed a retrospective analysis of 55 patients who underwent percutaneous nephrolithotomy and 75 patients who underwent retrograde intrarenal surgery between January 2016 and November 2018. Until operative success was achieved, all additional surgical procedures, extracorporeal shock wave lithotripsy procedures, and interventional procedures required to resolve complications were recorded. Total cost was compared between the percutaneous nephrolithotomy and retrograde intrarenal surgery groups. RESULTS: No significant difference was found between the percutaneous nephrolithotomy and retrograde intrarenal surgery groups in terms of gender, mean age, stone side, stone localization and stone surface area. The total cost of 55 patients that underwent percutaneous nephrolithotomy was calculated as US$14.766 after the first operation, and the total cost of 75 patients that underwent retrograde intrarenal surgery was determined to be US$46.627. The mean cost per patient was calculated US$320 ± US$186 for percutaneous nephrolithotomy and US$749 ± US$242 for retrograde intrarenal surgery (p < 0.001). CONCLUSIONS: Percutaneous nephrolithotomy is a lower-cost and successful method in the surgical treatment of 1-3 cm stones, but the serious complications involved in this operation should be kept in mind.

Stone-Free Rate after Treating Kidney Stones Exceeding 10 mm via Flexible Ureteroscopy: Can Endoscopic Assessment Replace Low-Dose Computed Tomography Control?

INTRODUCTION: It is unclear whether endoscopic assessment of the stone-free rate after flexible ureteroscopy (fURS) is as effective as assessment with low-dose computed tomography (CT) scan. METHODS: Prospective documentation of patients with kidney stones > 10 mm diameter from 2 different centers (Freiburg, Regensburg), who underwent fURS and were declared to be endoscopically completely stone-free. Low-dose CT control performed 4-8 weeks postoperatively. RESULTS/CONCLUSION: Thirty-eight patients were treated between October 2015 and August 2016 (12 F, 26 M). Average age was 55.9 years (range 19-82, SD 17.24), and body mass index was 29.7 kg/m2 (range 23.5-42.5, SD 4.37). There were 2.0 (range 1-7, SD 1.55) stones with a mean diameter of 15 mm (range 10-40, SD 6.78) per kidney. Mean surgery time was 74 min (range 38-124, SD 24.28), and lithotripsy was necessary in 33 cases. CT was performed 5.4 weeks afterwards (range 4-8, SD 1.43). One patient had a 2 mm residual which was extracted by URS. Strictly speaking, endoluminal stone removal control failed in only that patient, yielding a negative predictive value of 97%. A routine postoperative CT scan would thus appear unnecessary in the case of negative endoscopic control for residual fragments and should be avoided to reduce radiation exposure. Further investigations with larger patient populations are necessary.

Metabolic assessment of recurrent and first renal calcium oxalate stone formers.

OBJECTIVES: This study aimed to demonstrate the dominant role of metabolic disorders in the formation of calcium oxalate stones in patients with recurrent urolithiasis, as well as in patients experiencing their first episode of urolithiasis. PATIENTS AND METHODS: The records of the patients who attended our kidney stone outpatient clinics between 2008 and 2012 were reviewed, and the data of 318 calcium oxalate stone patients who had undergone a metabolic assessment were retrospectively analysed. The patients were divided in two groups. The first group included the patients who presented with their first episode of urolithiasis (Group 1, n = 170), and the second group included patients with recurrent urolithiasis (Group 2, n = 148); intergroup comparisons of metabolic disorders were performed. RESULTS: A significant difference was found between the two groups in mean urine calcium levels (Group 1, 0.25; Group 2, 0.31; p = 0.001); the mean serum calcium level was found to be significantly higher although at less extent in Group 2 (Group 1, 9.4; Group 2, 9.6); p = 0.04). Significant differences were also found in mean urine citrate (Group 1, 481.9; Group 2, 397.2, p < 0.0001) and oxalate levels (Group 1, 22.1; Group 2, 28.5; p < 0.0001) . CONCLUSIONS: This study revealed a metabolic tendency to hypercalciuria in calcium oxalate stone patients, predominantly in those with recurrent calcium oxalate urolithiasis. Urinary oxalate excretion was found to be higher in recurrent urolithiasis in comparison to the first episode of calcium oxalate urolithiasis and urinary citrate excretion lower in recurrent urolithiasis.

Assessment of Stone Complexity for PCNL: A Systematic Review of the Literature, How Best Can We Record Stone Complexity in PCNL?

INTRODUCTION: This study aims to systematically review the literature reporting tools for scoring stone complexity and the stratification of outcomes by stone complexity. In doing so, we aim to determine whether the evidence favors uniform adoption of any one scoring system. METHODS: PubMed and Embase databases were systematically searched for relevant studies from 2004 to 2014. Reports selected according to predetermined inclusion and exclusion criteria were appraised in terms of methodologic quality and their findings summarized in structured tables. RESULTS: After review, 15 studies were considered suitable for inclusion. Four distinct scoring systems were identified and a further five studies that aimed to validate aspects of those scoring systems. Six studies reported the stratification of outcomes by stone complexity, without specifically defining a scoring system. All studies reported some correlation between stone complexity and stone clearance. Correlation with complications was less clearly established, where investigated. CONCLUSIONS: This review does not allow us to firmly recommend one scoring system over the other. However, the quality of evidence supporting validation of the Guy's Stone Score is marginally superior, according to the criteria applied in this study. Further evaluation of the interobserver reliability of this scoring system is required.

Evaluation of low-dose dual energy computed tomography for in vivo assessment of renal/ureteric calculus composition.

PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. RESULTS: A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p<0.001). The DE ratio could confidently differentiate uric acid, struvite, calcium oxalate, and carbonate apatite calculi (p<0.001) with cutoff values of 1.12, 1.34, and 1.66, respectively, giving >80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.

Retrograde intrarenal surgery vs extracorporeal shock wave lithotripsy for intermediate size inferior pole calculi: a prospective assessment of objective and subjective outcomes.

OBJECTIVE: To assess objective and subjective outcomes of retrograde intrarenal surgery (RIRS) and extracorporeal shock wave lithotripsy (SWL) for the treatment of intermediate size (1-2 cm) inferior calyceal (IC) stones in a prospective randomized fashion. METHODS: Between March 2011 and January 2013, 70 symptomatic adults who had isolated IC stone between 10 and 20 mm underwent RIRS or SWL by computer-generated pseudorandom assignment (1:1). Success rate, mean procedure time, hospital stay, pain score on day 1 and 2 using visual analog scale, analgesic requirement after discharge, complications, retreatment rate, auxiliary procedure, and patient-reported outcomes (using self-made nonvalidated questionnaire) were compared. RESULTS: Baseline parameters and mean stone size (SWL 16.45 ± 2.28 mm, RIRS 15.05 ± 3.56 mm; P = .0542) were comparable. Success rate was significantly higher after a single session of RIRS compared with 3 sessions of SWL (85% vs 54%; P = .008). Retreatment rate (65% vs 5.7%; P = .0001) and auxiliary procedure (45% vs 8%; P = .0009) were significantly higher in SWL. Pain score on postoperative day 1 and 2 was significantly higher in RIRS, but patients with SWL required significantly more analgesics afterward. Most of the complications were of Clavien grade I and/or II in both groups. Average time to return to normal activity and voiding symptoms were significantly higher in RIRS. Overall satisfaction score (2.17 ± 1.24 vs 2.82 ± 1.17; P = .026) was significantly higher in RIRS than SWL. CONCLUSION: For the treatment of intermediate size IC calculi, RIRS is superior to SWL in terms of objective and subjective outcomes.

An update on percutaneous nephrolithotomy: lessons learned from the CROES PCNL Global Study.

Since its introduction in late 1970's, percutaneous nephrolithotomy (PNL) has undergone an evolution in both equipment and technique. This evolution still continues today in the era of minimally invasive treatment options, and is evidenced by the numerous publications. PNL is generally advantageous in the management of large renal stones (>1.5-2 cm) with high stone-free rates and considerable complication rates. However this technique is especially competing with retrograde intrarenal surgery and laparoscopic techniques. Therefore the CROES Global PNL Study Group prospectively collected data of over 5800 patients managed with PNL worldwide and analyzed the data in detail, producing more than 25 scientific papers. And this update focuses on the lessons learned from the CROES PCNL Global Study.

The most reliable preoperative assessment of renal stone burden as a predictor of stone-free status after flexible ureteroscopy with holmium laser lithotripsy: a single-center experience.

OBJECTIVE: To examine which parameters should be measured to preoperatively determine the stone burden as predictors of stone-free (SF) status after a single flexible ureteroscopy (URS). Although several stone parameters reportedly influence the outcome of treatment for urinary stones, the most reliable indicators of stone burden remain unclear. METHODS: Patients with renal stones treated by flexible URS with holmium laser lithotripsy between October 2009 and December 2011 at a single institute were retrospectively evaluated. The SF status was determined by kidney-ureter-bladder (KUB) films at postoperative day 1. Correlations of possible predictors with the SF status were analyzed using a logistic regression model. RESULTS: According to the univariate analysis, the following variables were significantly associated with failed treatment: number of stones (P = .001), cumulative stone diameter (CSD) (P < .001), stone surface area (SA) (P < .001), stone volume (P < .001), and presence of lower pole calculi (P = .008). According to the multivariate analysis, the stone volume (P < .001) and the CSD (P = .015) were found to be independent predictors of SF status. The SA (P = .598) had no significant independent influence on the SF status. CONCLUSION: Among the several parameters regarding the renal stone burden, the stone volume determined by noncontrast computed tomography and the CSD of the KUB were significantly and independently inversely related to the success rate of URS. Among the 3 parameters of stone burden, the SA was found to have a lower clinical utility and priority as a predictor of a SF status after URS.

Automated volumetric assessment by noncontrast computed tomography in the surveillance of nephrolithiasis.

OBJECTIVE: To evaluate the use of automated volumetric assessment for stone surveillance and compare the results with manual linear measurement. METHODS: We retrospectively reviewed patients seen in our stone clinic who had undergone 2 noncontrast computed tomography (NCCT) scans without stone intervention during the interval between scans. Thirty patients met our inclusion criteria and underwent longitudinal assessment for urolithiasis via NCCT (mean interval 583.2 days, range 122-2030). Fifty-two discrete calculi were analyzed. Three board certified radiologists measured maximal linear stone size in the axial plane using electronic calipers on soft tissue (ST) and bone windows (BWs). Automated stone volume was also obtained by each reader using a dedicated prototype software tool for stone evaluation. RESULTS: Mean stone linear size and volume was 4.9 ± 2.8 mm (ST), 4.5 ± 2.6 mm (BW), and 116.2 ± 194.6 mm(3) (window independent), respectively. Mean interobserver variability for linear size measurement was 16.4 ± 10.5% (ST) and 20.3 ± 13.8% (BW). Interobserver variability for volumetric measurement was 0%. Of the 52 persistent stones, the mean percent change in linear stone size between CT studies was 39.3 ± 46.7% (ST) and 42.9 ± 53.1% (BW) growth, compared with 171.4 ± 320.1% (window independent) growth for automated volume measurement over a mean of 583.2 days. However, discordant results for increased vs decreased interval size was seen between linear and volumetric assessment in 19/52 stones (36.5%). CONCLUSION: Automated volumetric measurement of renal calculi via NCCT is independent of specific reader and window settings. Volumetric assessment amplifies smaller linear changes over time, whereas as much as one third of cases show linear-volume measurement discordance. Volumetric assessment is therefore preferable, particularly for longitudinal surveillance of renal calculi.

Avaliaçäo de pacientes com litíase renal em regiäo de clima quente / Assessment of kidney stone patients in hot regions

O objetivo deste estudo é desenvolver um serviço de litíase renal e detectar as alteraçöes metabólicas associadas a essa doença em pacientes da cidade de Catanduva, Säo Paulo. Foram estudados 65 pacientes (40 mulheres e 25 homens), entre 1996 e 1999, com idade variando entre 18 e 67 anos. O protocolo utilizado consistiu de avaliaçäo clínica e exames complementares (bioquímica de imagem e dos principais elementos litogênicos plasmáticos e urinários). Para a análise dos resultados, foi utilizado o teste "t" de Student para amostras independentes e consideradas insignificantes quando p é menor que 0,05. Pelo menos, uma alteraçäo metabólica foi encontrada em 98,5 porcento dos casos avaliados.A reduçäo do volume urinário (77 porcento) foi a alteraçäo metabólica mais frequente, seguida pela hipocitratúria (62 porcento), hiperexcreçäo de ácido úrico (32 porcento), hipercalciúria (27 porcento), outras alteraçöes (8 porcento),e sem alteraçäo detectada (1,5 porcento). A detecçäo de, pelo menos, uma alteraçäo metabólica encontrada na grande maioria dos pacientes avaliados comprova a eficácia do protocolo aplicado nesse trabalho. O estudo sugere que a elevada prevalência de alteraçöes metabólicas associadas à litíase renal justifica a investigaçäo sistemática dos pacientes litiásicos. O estabelecimento de centros regionais com serviço de litíase renal deverá näo só favorecer aos pacientes dessas regiöes, bem como contribuir, no sentido epidemiológico, para um maior conhecimento dessa doença no Brasil.(au)

Outcome assessment of double-J stents during extracorporeal shockwave lithotripsy of small solitary renal calculi.

The utility of indwelling double-J ureteral stents during extracorporeal shockwave lithotripsy (SWL) of renal calculi is ill defined. We evaluated 179 patients treated with SWL for small (< 20 mm in diameter) solitary renal calculi with (N = 27) or without (N = 152) indwelling ureteral stents. There was no significant difference in the stone-free rates at 1 month (both 52%) and 3 months (61% nonstented group v 67% stented group; P = 0.45) or in the retreatment rates (13.3% nonstented group v 14.8% stented group; P = 0.60). The incidence and severity of pain/renal colic were similar for the two treatment groups. There was minimal morbidity associated with SWL in either group. Placement of double-J stents for the purpose of improving stone-free rates, alleviating pain, or preventing ureteral obstruction in conjunction with SWL of solitary renal calculi < 20 mm in diameter is unnecessary.