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The urine metabolites and chemistries that contribute to kidney stone formation are not fully understood. This study examined differences between the urine metabolic and chemistries profiles of first-time stone formers and controls.High-resolutionsup1/supH-nuclear magnetic resonance (NMR) spectroscopy-based metabolomic analysis was performed in 24-hour urine samples from a prospective cohort of 418 first-time symptomatic kidney stone formers and 440 controls. In total, 48 NMR-quantified metabolites in addition to 12 standard urine chemistries were assayed. Analysis of covariance was used to determine the association of stone former status with urine metabolites or chemistries after adjusting for age and sex and correcting for the false discovery rate. Gradient-boosted machine methods with nested cross-validation were applied to predict stone former status.Among the standard urine chemistries, stone formers had lower urine oxalate and potassium and higher urine calcium, phosphate, and creatinine. Among NMR urine metabolites, stone formers had lower hippuric acid, trigonelline, 2-furoylglycine, imidazole, and citrate and higher creatine and alanine. A cross-validated model using urine chemistries, age, and sex yielded a mean AUC of 0.76 (95% CI, 0.73 to 0.79). A cross-validated model using urine chemistries, NMR-quantified metabolites, age, and sex did not meaningfully improve the discrimination (mean AUC, 0.78; 95% CI, 0.75 to 0.81). In this combined model, among the top ten discriminating features, four were urine chemistries and six NMR-quantified metabolites.Although NMR-quantified metabolites did not improve discrimination, several urine metabolic profiles were identified that may improve understanding of kidney stone pathogenesis.

Purpose: We evaluated stone-free rate and complications after flexible ureteroscopy for renal stones, comparing thulium fiber laser and holmium:YAG laser with MOSES technology. Materials and Methods: Data from adults who underwent flexible ureteroscopy in 20 centers worldwide were retrospectively reviewed (January 2018-August 2021). Patients with ureteral stones, concomitant bilateral procedures, and combined procedures were excluded. One-to-one propensity score matching for age, gender, and stone characteristics was performed. Stone-free rate was defined as absence of fragments >2 mm on imaging within 3 months after surgery. Multivariable logistic regression was performed to evaluate independent predictors of being stone-free. Results: Of 2,075 included patients, holmium:YAG laser with MOSES technology was used in 508 patients and thulium fiber laser in 1,567 patients. After matching, 284 patients from each group with comparable baseline characteristics were included. Pure dusting was applied in 6.0% of cases in holmium:YAG laser with MOSES technology compared with 26% in thulium fiber laser. There was a higher rate of basket extraction in holmium:YAG laser with MOSES technology (89% vs 43%, P < .001). Total operation time and lasing time were similar. Nine patients had sepsis in thulium fiber laser vs none in holmium:YAG laser with MOSES technology (P = .007). Higher stone-free rate was achieved in thulium fiber laser (85% vs 56%, P < .001). At multivariable analysis, the use of thulium fiber laser and ureteral access sheath ≥8F had significantly higher odds of being stone-free. Lasing time, multiple stones, stone diameter, and use of disposable scopes showed significantly lower odds of being stone-free. Conclusions: This real-world study favors the use of thulium fiber laser over holmium:YAG laser with MOSES technology in flexible ureteroscopy for renal stones by way of its higher single-stage stone-free rate. Flexible ureteroscopy (F-URS) is a first-line option for kidney stones up to 2 cm in diameter1,2 and is suitable even for patients with larger stones,3 renal malformations,4 obesity, bleeding diathesis, and calyceal diverticula5 under general and spinal anesthesia,6 with good stone-free rate (SFR) and low morbidity. Over the past 3 decades, holmium laser lithotripsy has been predominantly carried out using standard-power machines (ie, 20 W). More recently, the availability of high power has allowed a wider range of pulse energy, frequency, and power settings to improve lithotripsy.7 In holmium:YAG laser (HL), variations in pulse modulation have introduced the concept of holmium:YAG laser with MOSES technology (HLM), virtual basket, and vapor tunnel allowing for more efficient stone ablation and less retropulsion.8 In vitro studies demonstrated that pulse modulation technology resulted in more efficient stone ablation together with less retropulsion for both hard and soft stones.9,10 Thulium fiber laser (TFL), which emerged in 2018,11 was found in preclinical studies to allow for ablation at twice the speed of HL with 4 times the amount of dust generated.12 Despite a recent single-center randomized clinical trial demonstrating no significant clinical advantage of one technology over the other,13 no direct comparison has been published comparing HLM with TFL in F-URS for renal stones in real-world practice, and much controversy continues to exist among experts in the field.14,15 The purpose of the present study was to evaluate outcomes and complications after F-URS for renal stones, comparing patients who were operated on using HLM vs TFL.

The aim of this study was to present the recent and promising innovations of the new laser technologies used for the treatment of renal stones.Taking advantage of pulse modulation, new technologies such as the Moses effect, the Virtual basket and the Vapor tunnel have been introduced. These technologies seem to improve lithotripsy efficacy by reducing retropulsion and increasing the stone ablation rate.High-power laser lithotripsy has arisen in everyday clinical practice in some centres. The combination of equal efficacy and safety levels compared with the low-power laser lithotripsy and significantly reduced operative time could explain this trend.Thulium fibre laser is an innovative type of laser-emitting machine that offers a lot of advantages compared with its predecessors. The different mechanism of creating the laser pulse offers new possibilities in laser lithotripsy and perhaps in the future thulium fibre laser could replace Ho:YAG as the golden standard for laser lithotripsy.Laser lithotripsy is heavily based on technological equipment. The continuous improvement of available lasers increases the endoscopic lithotripsy levels of efficacy and safety.

The puncture technique and site of the puncture can impact the clinical outcome and the development of postoperative adverse events following percutaneous nephrolithotomy (PCNL). The aim of the current review was to discuss the available puncture guidance approaches and outline the potential role of the recently introduced electromagnetic-guided method.The puncture and PCNL tract establishment is usually performed using fluoroscopic or ultrasound guidance or a combination of two approaches. Electromagnetic-guided puncture is one of the most recent advancements of technology. The puncture navigation to the renal collecting system is available after placing a special wire with an electromagnetic tracking sensor into the desired calyx through the flexible ureterorenoscope. The available experimental and clinical studies have shown a high first puncture rate, decreased median time for obtaining a puncture, and shorter learning curves for beginners.Fluoroscopic and ultrasound guidance are the main approaches used by urologists. However, these modalities require a steep learning curve, approximately 60 cases for reaching competency. The initial data on electromagnetic navigation have shown the feasibility and potential promising outcomes of this novel approach. New studies are required to investigate its potential implementation opportunities in the daily practice of urologists.

To confirm the need for a metabolic evaluation in stone formers based on the latest information published in the last 24 months and in the current 2022 American and European urological guidelines.Recent studies suggest that urolithiasis prevalence has been increasing since 1990. Along with it, metabolic abnormalities that contribute to the development of kidney stones are also increasing, such as hyperuricosuria, hyperoxaluria, hypocitraturia, hypomagnesuria, hypocalciuria, hypophosphaturia, and hyperuricemia. Those abnormalities can only be detected through a metabolic evaluation in patients with stone disease.It is important for us, urologists, to have in mind the actual stone prevalence worldwide. As part of our initial evaluation of the patient with urolithiasis, we must not forget to perform the basic metabolic analysis and, according to the patient's risk classification, continue with a deep metabolic analysis. This extensive analysis includes blood and urine tests. The urinalysis covers 24-h urinalysis, and it would be accurate to also have an early fresh urine analysis. Moreover, identifying the stone type is intimately correlated with the search for other metabolic parameters.

PURPOSE OF REVIEW: The aim of this study was to discuss current trends and recent developments in the surgical management of paediatric urolithiasis. RECENT FINDINGS: Medical expulsive therapy (MET) is considered as an option for the treatment of children with ureter stones. Extracorporeal shockwave lithotripsy (SWL) remains as a first option for majority of kidney stones and upper ureter stones. Advances in endourology have led to increased adoption of retrograde intrarenal surgeries (RIRS) and percutaneous nephrolithotomy (PCNL/mini-PCNL/ultra-mini-PCNL/micro-PCNL). SUMMARY: Management of paediatric stone disease has developed significantly in the past decade. However, the evidence in the literature remains disproportional to these advances. Well designed multicentric studies are still needed to compare effectiveness and safety of these procedures.

PURPOSE OF REVIEW: Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder that causes hepatic overproduction of oxalate and, often, nephrocalcinosis, nephrolithiasis, chronic kidney disease, and kidney failure. The purpose of the review is to provide an update on current emerging therapies for treatment of PH1. RECENT FINDINGS: Use of ribonucleic acid interference (RNAi) therapeutics that target the liver to block production of key enzymes along pathways that generate oxalate is a promising approach. Available evidence supports the efficacy of both Lumasiran (targeting glycolate oxidase) and Nedosiran (targeting hepatic lactate dehydrogenase (LDHa)) to reduce urinary oxalate excretion in PH1. The efficacy of alternative approaches including stiripentol (an anti-convulsant drug that also targets LDHa), lanthanum (a potential gastrointestinal oxalate binder), and Oxalobacter formigenes (a bacterium that can degrade oxalate within the gastrointestinal tract and may also increase its secretion from blood) are all also under study. Genetic editing tools including clustered regularly interspaced short palindromic repeats/Cas9 (CRISPR/Cas9) are also in preclinical study as a potential PH1 therapeutic. SUMMARY: Novel treatments can reduce the plasma oxalate concentration and urinary oxalate excretion in PH1 patients. Thus, it is possible these approaches will reduce the need for CLKT to significantly decrease the morbidity and mortality of affected patients.

PURPOSE Urinary stone disease (USD) has been associated with an increased risk of chronic kidney disease (CKD) and end-stage renal disease in Western populations. However, the metabolic disorders associated with unilateral and bilateral renal stones and the association of these types of stones with CKD and kidney tubular injury markers, such as urine N-acetyl-s-D-glucosaminidase (NAG) and alpha-1-microglobulin (α1-MG), have not been fully examined. MATERIALS AND METHODS We performed a cross-sectional study of 10,281 participants in rural China in 2014. All the subjects underwent renal ultrasound to detect USD; stone formers were divided into groups with unilateral or bilateral renal stones by ultrasound examinations. CKD was defined as a decreased estimated glomerular filtration rate (eGFR

PCNL (percutaneous nephrolithotomy) and its miniaturized variants are being widely employed in stone surgery, owing to their high-stone-free rates (SFRs) and efficacy for large (20 mm) stones. With advances in laser technology, it has been readily utilized in PCNL, with the potential for lower complication rates at similar SFR. We aimed to perform a systematic literature review with a focus on recent prospective clinical data that compares laser PCNL to either nonlaser PCNL, different PCNL sizes or other current standards of care such as shockwave lithotripsy (ESWL) or flexible ureteroscopy (FURS).Of the 294 studies initially identified through database searching, nine papers published between 2019 and 2021 were included which compared laser PCNL (Standard PCNL in three, mini-PCNL in four, ultra-mini PCNL in one, micro-PCNL in one study) to other nonlaser lithotripsy, ESWL, FURS, and different PCNL sizes. Complications for laser PCNL ranged from bleeding (4.4%), perirenal haematoma (1.1%), fever (4.6%), ureteric/renal pelvic injury (2.3%), haematuria (2.7%), and infection (2.6%). The mean SFR for laser PCNL was 91.5% at 3 months.Percutaneous laser nephrolithotripsy is well tolerated and effective, with high-SFRs at 3 months and relatively low intraoperative and postoperative complication rates. Further research is required to assess the role of intraoperative techniques and suction to improve outcomes further.

PURPOSE OF REVIEW: The aim of this study was to summarize recent findings in kidney gene therapy while proposing cystinuria as a model kidney disease target for genome engineering therapeutics. RECENT FINDINGS: Despite the advances of gene therapy for treating diseases of other organs, the kidney lags behind. Kidney-targeted gene delivery remains an obstacle to gene therapy of kidney disease. Nanoparticle and adeno-associated viral vector technologies offer emerging hope for kidney gene therapy. Cystinuria represents a model potential target for kidney gene therapy due to its known genetic and molecular basis, targetability, and capacity for phenotypic rescue. SUMMARY: Although gene therapy for kidney disease remains a major challenge, new and evolving technologies may actualize treatment for cystinuria and other kidney diseases.

Ureteral stents are commonly placed after ureteroscopy. Although studies indicate that stents are associated with patient discomfort, their impact on downstream health services use is unclear. We examined patterns of stent utilization in Michigan and their association with unplanned health care encounters.We used the Michigan Urological Surgery Improvement Collaborative's Reducing Operative Complications from Kidney Stones (MUSIC ROCKS) clinical registry to identify ureteroscopy cases between 2016 and 2019. Factors associated with stent placement were examined using bivariate and multivariable statistics. Using multivariable logistic regression, we evaluated whether stent placement was associated with emergency department visits and hospitalizations within 30 days.We identified 9,662 ureteroscopies and a stent was placed in 7,025 (73%) of these. Frequency of stent use across the 137 urologists varied (11%-100%, p0.001) and was not associated with total case volume. Factors associated with stent use included age and stone size. Pre-stented cases and renal stones had a decreased odds of stent placement. On multivariable analysis after adjusting for risk factors, stent placement was associated with a 1.25 higher odds of emergency department visit (OR 1.25, 95% CI 1.01-1.54, p=0.043) but not hospitalization (OR 1.28, 95% CI 0.94-1.76, p=0.12). In a single high volume practice, 0.5% of cases that omitted a stent required urgent stenting postoperatively.There is substantial variation in the use of stents in Michigan, irrespective of case volume. Stent placement significantly increased the odds of an emergency department visit after surgery. Importantly, stent omission rarely required subsequent urgent stent placement.

Purpose of review The armamentarium of percutaneous nephrolithotomy (PCNL) and the strategy to perform the procedure is constantly evolving. The innovation and development in techniques lead to further miniaturization in PCNL devices and change the lithotripsy and stone removal strategy. Suctioning in PCNL offers urologist a new conception in renal stone management. The present review evaluates the latest results on efficacy, safety and feasibility of suctioning PCNL techniques. Recent findings Recent literature reported the outcomes of different suctioning PCNL techniques. Most of these studies demonstrated good efficacy when comparing conventional PCNL. Suctioning PCNL improving the lithotripsy efficiency to enhance the stone-free rate (SFR) and reducing renal pelvic pressure to attenuate postoperative infectious complications. The advantage of suction also helps overcome the limitation of potentially higher intrarenal pressure and prolonged operative time in Mini-PCNL. Summary PCNL with suctioning represents a valuable new tool in the armamentarium of modern endourologists. This innovative approach can offer improved safety and efficacy with lower complications rates and higher cost effectiveness than the traditional PCNL technique.

Purpose of review This review provides a forecast about ongoing developments in the management of urolithiasis with a potential to challenge the current standard of care. We therefore emphasized innovative technology, which might be considered still experimental in the daily clinic or needs further clinical validation, but harbors the great potential to become a game changer for future stone management. Recent findings Especially in the endoscopic stone treatment, we observed a multitude of groundbreaking technical innovations, which changed our treatment algorithms over the last decades. Some of this technology already found its way into daily practice. Others like artificial intelligence, burst wave lithotripsy, smart laser systems or gene therapy may not be standardized yet, but have the potential to further revolutionize current practice. Besides those technical features, we included innovations in prevention and diagnostics, as well as patient expectations and patient satisfaction into the analysis. A proper metaphylaxis and patient communication seems to be essential for a long-lasting treatment success. Summary The combination of technical innovations, improved stone metaphylaxis and proper patient communication presents the cornerstone of future kidney stone management.

Purpose of review There is an ongoing explosion in the amount and quality, of research in the field of Endourology. From a solid basis of systematic reviews and small, single centre trials it has been possible to design large randomised controlled trials in the UK and in the USA. This review will describe some of the more recent trials (small and large) that are helping to provide a solid evidence base for our practice in Endourology. Ongoing studies Randomised controlled trial (RCTs) include: The Therapeutic Interventions for Stones in the Ureter (TISU), the Percutaneous nephrolithotomy, flexible Ureterorenoscopy and extracorporeal Shockwave lithotripsy for lower pole kidney stones (PURE RCTs) and the Prevention of Urinary Stones with Hydration (PUSH). Quality of life (QoL) measures and studies include: the Wisconsin Stone QoL Questionnaire, the Cambridge Renal Stone PROM, the Cambridge Ureteral Stone PROM, the Urinary stone and Intervention QoL questionnaire and the Study to Enhance Understanding of sTent-associated Symptoms (STENTS). The Core Outcome Set in Trials on treatments for Renal and UreteriC sTones (COSTRUCT) study aims to define a core outcome set to be used in future trials. Summary On-going studies will provide higher quality evidence on the treatment of ureteric and renal stones to inform treatment decision making and guideline recommendations. They will also guide decisions relating to prevention and recurrence and give insight into the true impact of urinary stones and endourological interventions on patients' quality of life. Future studies will incorporate big data and artificial intelligence.

Purpose of review Recent years witnessed significant changes in the endourological management of renal tones because of the development of new, more advanced instruments. Retrograde intrarenal surgery (RIRS) has gained particular advantage from such technological progress and now tends to be considered the gold standard treatment for uncomplicated less than 20 mm renal stones. Using a step-by-step approach, this review aims to highlight current achievements but also unsolved problems in RIRS. Recent findings Several technical details of RIRS, including preoperative stenting, use of ureteral access sheets, lithotripsy method, and renal drainage, remain open to discussion and linked to surgeon's preference. Moreover, there is a wide range of variation in efficacy and safety data, with major complications being episodic but often under-reported. Summary RIRS has gained increased popularity among the urological community. This is certainly because of the continuous technological advancements, which have continuously improved the RIRS performance but also to the perception of ease and safety of this procedure when compared with the other available treatment modalities, particularly percutaneous nephrolitotomy. Indeed, the reported advances in RIRS technique have significantly improved the outcomes of this procedure but care should be taken not to underestimate its potential challenges.

Purpose of review Urinary biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and N-acetyl-B-D-glucosamindase (NAG) are recognised as being useful for the detection of kidney tubular damage but their role in the diagnosis and prognosis of kidney stone disease (KSD) is still unknown. To clarify this, we performed a systematic review of literature in accordance with Cochrane methodology from inception to September 2020. Recent findings Twelve studies were included and a variety of urinary biomarkers (KIM-1, NGAL, NAG, proteins/peptides, cytokines, CA19-9) were measured in a total of 998 patients with KSD. Despite some contradicting studies, majority of the biomarkers studied showed a significant rise in patients with KSD compared to healthy controls, with levels decreasing after their surgical management, noticed as early as 4 h postprocedure. There was limited evidence of correlation with stone burden and elevated levels were also associated with hydronephrosis and superimposed infections. Summary Urinary biomarkers could be used in the diagnosis, prognosis and stone-treatment response in patients with KSD. However, as novel indicators, they may not be reliable as the sole diagnostic or prognostic tool for KSD as they are readily confounded by other causes of kidney injury. Further studies are needed to determine their ability to separate KSD from other causes of obstructive uropathy and acute renal injury.

Purpose of review Surgical management is the cornerstone of urolithiasis treatment, but high recurrence rates and associated complications necessitate the existence of medical treatment options, aiming at dissolution of kidney stones and prevention of recurrence. The purpose of this review is to present the most recent knowledge existing in scientific literature, regarding dissolution therapy and ways of monitoring nephrolithiasis patients. Recent findings A number of laboratory studies have been performed testing experimental treatments (tolvaptan, chlorthalidone, atorvastatin, a-lipoic acid, glucosaminoglycans, plant extracts), to reduce kidney stone formation and cellular damage and showed encouraging results. Uric acid stones is the main target of dissolution therapy, but until last years, existing level of evidence was low. A number of prospective and randomized studies, proved the efficacy and safety of oral chemolysis for radiolucent stones and associated prognostic features of success. Tolvaptan and a-Lipoic acid were also tested in patients with cystinuria and resulted in reduction of recurrence. Finally, some new diagnostic markers are suggested as tests for the monitoring of urolithiasis patients, with satisfying accuracy and discriminative ability. Summary Medical dissolution therapy for nephrolithiasis is an effective option, especially for patients with radiolucent/uric acid stones. In the future, we need clinical trials to confirm the encouraging results of pilot studies testing several agents for patients with cystinuria.

BACKGROUND: Hyperoxaluria is typically associated with excessive oxalate intake in the diet, decreased dietary calcium, hyperabsorption of oxalate, or increased endogenous production of oxalate. The disorder spectrum extends from recurrent kidney stones to ESKD. This clinical trial sought to evaluate the effectiveness of an acid stable oxalate decarboxylase (OxDC) to reduce urinary oxalate in healthy subjects on a high-oxalate diet. METHODS: In this prospective, double-blind, randomized, placebo-controlled, crossover clinical trial, 33 healthy volunteers were randomized into two crossover sequences separated by a 2-day washout period. A controlled high-oxalate diet (750–800 mg oxalate, 500–550 mg calcium daily) was utilized, and six 24-hour urine collections were measured. Subjects were given approximately 1000 U (micromoles per minute per milligram) of OxDC or placebo with meals three times daily during the 4 days of treatment. RESULTS: Urinary oxalate significantly decreased with OxDC treatment. The baseline corrected within-subject mean reduction in 24-hour urinary excretion (after OxDC dosing versus high-oxalate baseline preceding treatment) was 12.5 mg or 29% (P5% reduction) in 31 of 33 subjects (94%). Compared with placebo, OxDC produced a 24% reduction (P

Retention of ureteral catheter to establish artificial hydronephrosis is a routine step of percutaneous nephrolithotomy procedure, which can improve the success rate of puncture, but it can prolong the procedure time and increase the risk of postoperative infection, especially for immunocompromised elderly patients. Therefore, this study aims to investigate the safety and effectiveness of ultrasound-guided percutaneous nephrolithotomy without indwelling ureteral catheter for older patients with upper urinary calculi. The clinical data of 119 older patients admitted to the Affiliated Hospital of Jining Medical University for percutaneous nephrolithotomy from January 2019 to December 2021 were retrospectively analyzed. The patients were divided into study and control groups according to whether the physician decided to use ureteral catheter during the procedure, and the differences in the success rate of one-time puncture, operative time, single-stage stone removal rate, postoperative hospital stay, and complication rate were compared between the 2 groups. There were no significant differences in the success rate of one-time puncture and single-stage stone removal rate between the 2 groups (P .05). The operation time were significantly shorter in the study group [(30.0-61.0) minute vs (54.8-106.8) minute, P = .00], and the intraoperative bleeding was less in the study group [(5-20) mL vs (10-30) mL, P = .03]. The postoperative hospital stay was shorter in the study group [(2.5-4.0) days vs (3.0-5.0) days, P = .00], and the medical expenses were lower in the study group [(17,309.5-22,652.7) yuan vs (19,148.0-24,407.6) yuan, P = .02]. The incidence of systemic inflammatory response syndrome was lower in the study group (3.5% vs 19.4%, P = .007). There were no statistically significant differences in complications such as postoperative fever, renal artery embolism and blood transfusion between the two groups (P .05). Ultrasound-guided percutaneous nephrolithotomy without indwelling ureteral catheter for elderly patients with upper urinary stones is safe and feasible.

Purpose: The aim of the current systematic review and meta-analysis is to provide an answer on which is the most appropriate approach for the management of the lower pole stones with a maximal dimension of 2 cm or less. Materials and Methods: A systematic review was conducted on PubMed (R), SCOPUS (R), Cochrane and EMBASE (R). The PRISMA guidelines and the recommendations of the EAU Guidelines office were followed. Retrograde intrarenal surgery, shock wave lithotripsy and percutaneous nephrolithotomy were considered for comparison. The primary end point was the stone-free rate. Results: A total of 15 randomized controlled trials were eligible. Percutaneous nephrolithotripsy and retrograde intrarenal surgery have higher stone-free rates in comparison to shock wave lithotripsy and require fewer re-treatment sessions. Operative time and complications seem to favor shock wave lithotripsy in comparison to percutaneous nephrolithotripsy, but this takes place at the expense of multiple shock wave lithotripsy sessions. Retrograde intrarenal surgery seems to be the most efficient approach for the management of stones up to 1 cm in the lower pole. Conclusions: The pooled analysis of the eligible studies showed that the management of lower pole stones should probably be percutaneous nephrolithotripsy or retrograde intrarenal surgery to achieve stone-free status over a short period and minimal number of sessions. For stones smaller than 10 mm, retrograde intrarenal surgery is more efficient in comparison to shock wave lithotripsy. The decision between the 2 approaches (percutaneous nephrolithotripsy or retrograde intrarenal surgery) should be individual, based on the anatomical parameters, the comorbidity and the preferences of each patient.

Purpose of review An overly acidic urine resulting in supersaturation of urine with respect to uric acid is the major mechanism responsible for uric acid nephrolithiasis. The present review summarizes findings from recent human physiologic studies examining the pathophysiology and reversibility of low urine pH in uric acid stone formers. Recent findings Epidemiologic and metabolic studies have confirmed an increase in the prevalence of uric acid nephrolithiasis and reported its association with several features of the metabolic syndrome including dyslipidemia, hyperglycemia, hepatic steatosis, and greater visceral adiposity. Physiologic studies in uric acid stone formers have identified diet-independent excessive net acid excretion and concomitant reduction in urinary buffering from impaired renal ammoniagenesis as the two causes underlying the greater aciduria. Administration of the insulin sensitizer pioglitazone to uric acid stone formers reduced the acid load presented to the kidney and enhanced ammoniagenesis and ammonium excretion, resulting in significantly higher urine pH. Summary Recent human physiologic studies have identified greater acid excretion and reduced urinary buffering by ammonia as two culprits of aciduria in uric acid nephrolithiasis that can be reversed by pioglitazone, raising new questions regarding the origin of the aciduria and opening the door to pathophysiology-based treatment of uric acid stones.

Background Some, but not all, patients with primary hyperparathyroidism (PHPT) and kidney stone disease (KSD) are cured of their nephrolithiasis after parathyroidectomy. The goal of this study was to identify risk factors for recurrent KSD despite successful parathyroidectomy in known stone formers with PHPT. Study design We conducted a single-center retrospective review of patients presenting to urology clinic with KSD between January 2008 and July 2018, who were diagnosed with concurrent PHPT, and underwent definitive parathyroidectomy. Laboratory testing for serum calcium, PTH (parathyroid hormone), phosphorus and 25-OH-vitamin D, and 24-hour urine studies for volume, pH, calcium, citrate, oxalate, uric acid, sodium, and creatinine was performed pre- and post-parathyroidectomy. Stone recurrence was determined on routine diagnostic imaging or by symptomatic KSD. Results Mean age at parathyroidectomy was 57 ± 14 years. Pre-parathyroidectomy, mean serum calcium, 24-hour urine calcium, and PTH were 10.6 ± 0.5 mg/dL, 378 ± 209 mg/day, and 114 ± 97 pg/mL, respectively. Twenty-six of 69 patients (38%) had multigland parathyroid disease. After parathyroidectomy, serum calcium and PTH levels normalized in 69 of 69 and 62 of 69 patients, respectively. However, 37 of 69 patients (54%) had persistent hypercalciuria postoperatively, and 16 of 69 (23%) had recurrent KSD, on average, 2.0 ± 1.6 years after parathyroidectomy. Patients with recurrent KSD post-parathyroidectomy were significantly younger compared with patients without recurrent KSD (51 ± 15 vs 60 ± 13 years, p = 0.02). In a logistic regression model, younger age remains a strong predictive factor for recurrent KSD. Conclusions Nearly one-quarter of PHPT patients with KSD who undergo successful parathyroidectomy present with recurrent KSD despite normalization of serum calcium, and more than half exhibit persistent calciuria. These patients were younger and may require closer monitoring for stone recurrence after successful parathyroidectomy. Further studies are needed to better identify the etiology of KSD post-parathyroidectomy.

A 42-year-old woman underwent 131I radiotherapy for thyroid papillary cancer. A focal elevated 131I activity in the right kidney was revealed on the initial whole-body posttherapeutic images, which was located in the region of a renal stone. However, on the follow-up 131I images acquired 6 months later, there was no longer any increased activity in the region of this stone, which had moved into right ureter. Our case indicates that the 131I activity accumulated in the region of urinary stone is due to stagnated radioactive urine rather than due to the stone per se.

BACKGROUND AND OBJECTIVES: Incidence of kidney stone disease is rising. It is not known whether mechanisms of stone formation differ across racial groups. Our objective was to identify differing lithogenic risk factors across racial groups in idiopathic nephrolithiasis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We conducted a retrospective cohort study evaluating metabolic risk factors in black and age-matched white idiopathic stone formers at our tertiary referral center. We compared serum and urine metabolic risk factors pre- and post-treatment across racial groups using analysis of covariance. Generalized linear modeling was used to build regression models for risk of stone formation in both groups. RESULTS: Among 117 black and 172 white stone formers, urine volume was lower in black stone formers (1.4±0.8 versus 2.0±0.8 L/d, P

Background The relationship between the composition and function of gut microbial communities and early-onset calcium oxalate kidney stone disease is unknown. Methods We conducted a case-control study of 88 individuals aged 4-18 years, which included 44 individuals with kidney stones containing ≥50% calcium oxalate and 44 controls matched for age, sex, and race. Shotgun metagenomic sequencing and untargeted metabolomics were performed on stool samples. Results Participants who were kidney stone formers had a significantly less diverse gut microbiome compared with controls. Among bacterial taxa with a prevalence >0.1%, 31 taxa were less abundant among individuals with nephrolithiasis. These included seven taxa that produce butyrate and three taxa that degrade oxalate. The lower abundance of these bacteria was reflected in decreased abundance of the gene encoding butyryl-coA dehydrogenase (P=0.02). The relative abundance of these bacteria was correlated with the levels of 18 fecal metabolites, and levels of these metabolites differed in individuals with kidney stones compared with controls. The oxalate-degrading bacterial taxa identified as decreased in those who were kidney stone formers were components of a larger abundance correlation network that included Eggerthella lenta and several Lactobacillus species. The microbial (α) diversity was associated with age of stone onset, first decreasing and then increasing with age. For the individuals who were stone formers, we found the lowest α diversity among individuals who first formed stones at age 9-14 years, whereas controls displayed no age-related differences in diversity. Conclusions Loss of gut bacteria, particularly loss of those that produce butyrate and degrade oxalate, associates with perturbations of the metabolome that may be upstream determinants of early-onset calcium oxalate kidney stone disease.

Purpose of review Urinary stone disease (USD) is increasing in prevalence and recurrence is common. In pediatrics, most stones are composed primarily of calcium with the highest incidence observed in adolescents. Given the morbidity associated with USD, an in depth review of current management strategies is of paramount importance to highlight the data supporting the recommended treatments and the knowledge gaps which still exist. Recent findings Several interventions for the management of recurrent calcium USD in children have been recommended based on primarily adult studies. These interventions include modification of diet and fluid intake in addition to the utilization of medications such as thiazide diuretics and citrates when supportive care is inadequate. Overall there is conflicting data in the adult literature which is further complicated by our attempts to extrapolate these data to children. Summary Based on the currently available literature the management of USD in pediatrics should be individualized to each patient and focused on the particular metabolic risk factors that are identified during the course of their evaluation. Several interventions may be required or trialed in a particular patient to show an effect. Well designed trials to assess the efficacy of each intervention in the pediatric population are needed.

Purpose of review As the incidence of nephrolithiasis in children doubles every 10 years it is becoming a common disease associated with significant morbidity along with considerable economic burden worldwide. The aim of this review is to summarize current data on the epidemiology and causes of renal stones in children and to provide a frame for the first clinical evaluation of a child with suspected nephrolithiasis. Recent findings Dietary and environmental factors are the driving force of changing epidemiology. Diagnosis should be based on medical history, presenting signs, examination, first laboratory and radiological workup. Ultrasound should be the initial diagnostic imaging performed in pediatric patients while low-dose computed tomography is rarely necessary for management. Metabolic factors including hypercalciuria, hypocitraturia, low fluid intake as well as specific genetic diseases should be explored after the resolution of initial signs and symptoms. Summary Appropriate initial evaluation, imaging technique, identification of risk factors and other abnormalities are essential for early diagnosis and prevention of stone-related morbidity in children with suspected nephrolithiasis.

Purpose of review Prevalence of pediatric urolithiasis is increasing, which is definitively visible in increasing numbers of presentations in emergency or outpatient clinics. In pediatric patients, a genetic or metabolic disease has to be excluded, so that adequate treatment can be installed as early as possible. Only then either recurrent stone events and chronic or even end-stage kidney disease can be prevented. Recent findings The genetic background of mostly monogenic kidney stone diseases was unravelled recently. In hypercalcuria, for example, the commonly used definition of idiopathic hypercalciuria was adopted to the genetic background, here three autosomal recessive hereditary forms of CYP24A1, SLC34A1 and SLC34A3 associated nephrocalcinosis/urolithiasis with elevated 1.25-dihydroxy-vitamin D3 (1.25-dihydroxy-vitamin D3) (calcitriol) levels. In addition either activating or inactivating mutations of the calcium-sensing receptor gene lead either to hypocalcemic hypercalciuria or hypercalcemic hypocalciuria. In primary hyperoxaluria, a third gene defect was unravelled explaining most of the so far unclassified patients. In addition, these findings lead to new treatment options, which are currently evaluated in phase III studies. Summary Kidney stones are not the disease itself, but only its first symptom. The underlying disease has to be diagnosed in every pediatric patient with the first stone event.

Purpose of review The review of potential therapies in the treatment of hyperoxaluria is timely, given the current excitement with clinical trials and the mounting evidence of the importance of oxalate in both kidney stone and chronic kidney disease. Recent findings Given the significant contribution of both endogenous and dietary oxalate to urinary oxalate excretions, it is not surprising therapeutic targets are being studied in both pathways. This article covers the existing data on endogenous and dietary oxalate and the current targets in these pathways. Summary In the near future, there will likely be therapies targeting both endogenous and dietary oxalate, especially in subsets of kidney stone formers.

Purpose of review The purpose of this review is to summarize recent developments in the array of devices which are commonly used by urologists in the surgical management of kidney stones. To accomplish this goal, an extensive review of recent endourology literature, conference abstracts, and publicly available documents from manufacturers and the United States Food and Drug Administration was collected and reviewed. Recent findings Recent developments in the holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy include the introduction of pulse modulation. This technique delivers the laser energy in an asymmetric manner such that an initial bubble is created (the 'Moses effect') through which the remainder of the energy can then travel through without being absorbed by surrounding water. Even more novel is the thulium fiber laser, which is produced in a fundamentally different way than traditional Ho:YAG lasers and is not yet available for clinical use. Finally, novel mechanical lithotrites which effectively combine ultrasonic energy, ballistic energy, and suction capability appear to be highly effective for stone clearance in recent benchtop and clinical studies. Summary With the introduction of both new modifications of time-tested technologies as well as completely novel modalities, the practicing urologist's armamentarium of devices for the surgical management of kidney stones continues to grow. As the popularity of 'mini' procedures continues to grow, the adaptability of these technologies to these procedures will be critical to maintain maximum relevance.

High animal protein intake is a risk factor for nephrolithiasis. Whether plant based sources of protein are associated with kidney stone risk is not well studied. We examined the association of animal and plant protein intake with the risk of incident kidney stones in Shanghai, China.Dietary intakes were obtained from a validated food frequency questionnaire at baseline. Self-reported stone events were ascertained at baseline and at followup visits. Multivariable Cox regression models were used to evaluate the associations of protein intake with the incident stone risk.During 319,211 and 696,950 person-years of followup 1,451 men and 1,202 women, respectively, reported incident stones. The average ± SD intake of animal and plant protein standardized to 2,000 kcal was 31.3 ± 13.7 and 48.4 ± 7.2 gm per day in women, and 30.8 ± 13.3 and 51.3 ± 7.6 gm per day, respectively, in men. On multivariable analysis participants in the highest quintiles of animal and nondairy animal protein intake showed an increased risk of incident stones compared to those in the lowest quintiles (HR 1.16, 95% CI 1.01-1.32, p=0.03 vs HR 1.14, 95% CI 1.01-1.30, p=0.04). Compared to the lowest quintile the highest intake quintiles of the animal-to-plant protein ratios and the nondairy animal-to-plant protein ratios were positively associated with stone risk (HR 1.17, 95% CI 1.03-1.33, p=0.02 and HR 1.20, 95% CI 1.06-1.36, p=0.005, respectively). No association was observed with plant protein intake (pIn this population with a relatively low animal protein intake and a high plant protein intake, a greater animal protein intake was associated with a kidney stone risk. Increasing the proportion of plant protein relative to animal protein appeared protective against the risk.

In this study we assessed the effects of a ramping protocol in patients undergoing extracorporeal shock wave lithotripsy of renal stones.In this prospective study patients with renal stones were randomized to receive shock wave lithotripsy delivered using a ramping protocol in group 1 (first 1,000 shocks at energy level 5 followed by 1,000 shocks at energy level 6 and 1,000 final shocks at energy level 7) and a fixed voltage protocol in group 2 (all 3,000 shocks at energy level 7). Treatment was administered using a Modulith® SLX-F2. The primary outcome was treatment success 12 weeks after a single shock wave lithotripsy session, defined as lack of a stone or a less than 4 mm stone fragment on computerized tomography. Other outcomes included the stone-free rate and the perinephric hematoma incidence.A total of 300 patients (150 per group) were recruited between February 2016 and June 2018. The 2 groups did not differ in baseline parameters. Group 1 received 14.8% lower energy than group 2, which was significant (p0.001). The treatment success rate in groups 1 and 2 was 67.8% and 73.6%, respectively, which did not statistically differ (group 1 crude OR 0.753, 95% CI 0.456-1.244, p=0.268). The stone-free rate in groups 1 and 2 was 36.6% and 41.9%, respectively, which did not differ statistically between the groups. However, in groups 1 and 2 perinephric hematoma developed in 23.8% and 43.8% of patients, respectively, which was a statistically significant difference (p0.001).The fixed voltage shock wave lithotripsy and ramping protocols provided similar treatment success rates for renal stones. However, the ramping protocol reduced the incidence of perinephric hematoma after shock wave lithotripsy.

Renal transplant is needed for end-stage renal disease. Although treatment of donor stones may be needed pretransplant and increases the pool available for renal transplant, posttransplant stone disease may also need treatment to maintain the allograft function. A Cochrane style review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines to evaluate the outcomes of donor and posttransplant ureteroscopy (URS) for stone disease, including all English language articles between January 1996 and December 2018.Eighteen articles (167 patients), seven ex-vivo or donor URS and 11 posttransplant URS met inclusion criteria and were included in the review. A pretransplant URS showed a stone-free rate (SFR) of 100% with an overall complication rate of 7.5% (four Clavien I and one Clavien ≥3), where as a posttransplant URS showed SFR of 100% in five studies and 60-91% in four studies with an overall complication rate of 12.9% (10 Clavien I and three Clavien ≥3).Advancements in endourological technique has made URS for donor and posttransplant urolithiasis a safe and effective procedure. Although data were based on small retrospective caser series, it shows that in experienced centres it can be performed with low morbidity and a high SFR.

Kidney stones are a source of significant morbidity which have been shown to negatively impact health related quality of life. We sought to understand the association between health related quality of life, socioeconomic status and race among patients with kidney stones.Patients with stones at a total of 11 stone centers across the United States completed the WISQOL (Wisconsin Stone Quality of Life questionnaire). The patient ZIP Code™ was used to estimate household income. A mixed effects regression model was constructed for analysis with ZIP Code as the random intercept.A total of 2,057 stone formers completed the WISQOL. Lower income was independently associated with significantly lower health related quality of life (β = 0.372, p = 0.014), as were nonwhite race (β = -0.299, p = 0.001), unemployed work status (β = -0.291, p = 0.008), female gender (β = -0.204, p0.001), body mass index greater than 40 kg/mLower income, nonwhite race and unemployed work status were independently associated with lower health related quality of life among patients with kidney stones. While clinical characteristics such as body mass and stone disease severity were also associated with health related quality of life, this study shows that socioeconomic factors are similarly important. Further research to understand the specific mechanisms by which socioeconomic status and race impact health may lend insight into methods to optimize clinical treatment of stone formers and patients with other chronic diseases.

To evaluate whether the higher attenuation value [Hounsfield unit (HU)] in non-contrast CT can predict pyonephrosis in patients with upper urinary tract stones (UTS). Between October 2019 and October 2021, patients with hydronephrosis or pyonephrosis secondary to upper UTS were retrospectively searched in our study. All patients with UTS were treated with percutaneous nephrostomy, percutaneous nephrolithotomy, retrograde ureteral stent or transurethral ureteroscope lithotripsy. We excluded patients treated with extracorporeal shock-wave lithotripsy. Patients whose CT was not performed in our hospital or treated in another hospital were also excluded. Clinical data regarding basic information, clinical feature, Calculi-related indicators, HU values of the renal pelvis, the thick wall of the renal pelvis on CT were collected. Univariate and multivariate logistic analyses were performed. Receiver operative characteristic curves were drawn to predict pyonephrosis. A total of 240 patients with UTS were retrospected in this research, 191 patients had hydronephrosis (Group 1), and 49 patients had hydronephrosis with pyonephrosis (Group 2). The HU value of the renal collecting system in Group 2 (mean, 15.46; range, +1/+30) was significantly higher than that in Group 1 (mean, 5.5; 5 range -6/+24) (P = .02); the receiver operative characteristic curve analysis revealed that the best cut-off value of 9.5 could predict the presence of pyonephrosis, with 71.4% sensitivity and 70.2% specificity (area under the curve = 0.613; 95% CI: 0.514-0.713). In this study, we found the HU attenuation value of the renal collecting system can be used to distinguish pyonephrosis from hydronephrosis in patients with UTS.

To assess the efficacy and safety of robot-assisted anatrophic nephrolithotomy (RANL) as a choice of minimally invasive treatment for patients with complete staghorn stone. In a single-tertiary referral center retrospective study, 10 consecutive patients underwent RANL for complete staghorn stone. After dissection to the renal hilum and clamping of the renal vessels, an incision was made along the Brodel line and exposed the collecting system to extract the stone. Then, the collecting system and parenchyma were closed in layers. The outcomes included reduction of the stone burden, short- and long-term postoperative kidney function, and pain score. The average age of patients was 54.6 years and body mass index was 27.58 kg/m2. Mean warm ischemia time was 28.40 minutes, mean robotic console time was 137 minutes, and mean estimated blood loss was 83 mL. The mean length of stay was 5.4 days and there were no severe perioperative complications. Eight of 10 patients had90% reduction in stone burden and 5 (50%) patients were completely stone-free. There was no significant decrease in postoperative estimated glomerular filtration rate compared with preoperative values after 1 month and 1 year. Our experience with RANL demonstrated efficacy and safety in the minimally invasive treatment of complete staghorn stone in short- and long-term follow-up periods.

To investigate how the risk factors of metabolic diseases affect urinary stone composition, particularly uric acid (UA) stones. Overall, 583 patients with data on urinary stone composition were retrospectively analyzed and classified into UA and nonUA stone formers according to the presence of the UA component. Various factors were compared between both groups. Participants were categorized according to age, glucose level, HbA1c level, and estimated glomerular filtration rate (eGFR) into subgroups, and the incidence of UA stone was compared. Overall, 137 UA stone formers (23.5%) and 446 nonUA stone formers (76.5%) were included. Mean age and male-to-female ratio were higher in the UA group than in the nonUA group. The rates of diabetes mellitus (DM), hypertension, chronic kidney disease, and coronary artery disease, all of which were associated with differences in urinary stone composition, were higher in the UA group than in the nonUA group. The UA group exhibited lower mean eGFR and higher glucose and HbA1c levels. Similarly, the UA group had higher mean UA levels and predictably lower urinary pH. In subgroup analysis, higher age, glucose level, HbA1c level, and lower eGFR were associated with an increased risk of UA stone formation. In the multivariate logistic regression analysis, the UA group showed a significantly higher age (P.001), DM frequency (P = .049), and HbA1c level (P = .032), but significantly lower eGFR than the nonUA group (P.001). Age and DM were independent risk factors for UA urolithiasis, implying a relationship between urinary stone composition and metabolic diseases. Additionally, renal function and HbA1c level were risk factors for UA stones.

Background Cystinuria is an inherited disorder of renal amino acid transport that causes recurrent nephrolithiasis and significant morbidity in humans. It has an incidence of 1 in 7000 worldwide making it one of the most common genetic disorders in man. We phenotypically characterized a mouse model of cystinuria type A resultant from knockout of Slc3a1. Methods Knockout of Slc3a1 at RNA and protein levels was evaluated using real-time quantitative PCR and immunofluorescence. Slc3a1 knockout mice were placed on normal or breeder chow diets and evaluated for cystine stone formation over time suing x-ray analysis, and the development of kidney injury by measuring injury biomarkers. Kidney injury was also evaluated via histologic analysis. Amino acid levels were measured in the blood of mice using high performance liquid chromatography. Liver glutathione levels were measured using a luminescent-based assay. Results We confirmed knockout of Slc3a1 at the RNA level, while Slc7a9 RNA representing the co-transporter was preserved. As expected, we observed bladder stone formation in Slc3a1−/− mice. Male Slc3a1−/− mice exhibited lower weights compared to Slc3a1+/+. Slc3a1−/− mice on a regular diet demonstrated elevated blood urea nitrogen (BUN) without elevation of serum creatinine. However, placing the knockout animals on a breeder chow diet, containing a higher cystine concentration, resulted in the development of elevation of both BUN and creatinine indicative of more severe chronic kidney disease. Histological examination revealed that these dietary effects resulted in worsened kidney tubular obstruction and interstitial inflammation as well as worsened bladder inflammation. Cystine is a precursor for the antioxidant molecule glutathione, so we evaluated glutathione levels in the livers of Slc3a1−/− mice. We found significantly lowered levels of both reduced and total glutathione in the knockout animals. Conclusions Our results suggest that that diet can affect the development and progression of chronic kidney disease in an animal model of cystinuria, which may have important implications for patients with this disease. Additionally, reduced glutathione may predispose those with cystinuria to injury caused by oxidative stress. Word count: 327. Electronic supplementary material The online version of this article (10.1186/s12882-019-1417-8) contains supplementary material, which is available to authorized users.

PURPOSE OF REVIEW Better understanding of sex differences affecting urolithiasis may help us offer tailored treatment strategies to our patients. RECENT FINDINGS The incidence of urolithiasis is increasing and the male-to-female ratio has decreased from 3 : 1 to 1.3 : 1 between 1970 and 2000. In women, obesity has a larger effect on the risk of developing urolithiasis [odds ratio (OR) 1.35; 95% confidence interval (CI): 1.33-1.37] compared with men (OR 1.04; 95% CI: 1.02-1.06). Urolithiasis is a risk factor for coronary artery disease in men (risk ratio = 1.23; 95% CI: 1.02-1.49) and for stroke in women (risk ratio = 1.12; 95% CI: 1.03-1.21). Women tolerate cystoscopic stent removal and shock wave lithotripsy better than men. For shock wave lithotripsy menopaused women have reported lower visual analog scale scores than menstruating women (P

To give an overview about state-of-the-art antibiotic prophylaxis in urolithasis therapy and focus on recent publications in this field.The number of high-quality publications within the recent time is limited. Preoperative inflammatory blood parameters like C-reactive protein and erythrocyte-sedimentation rate might help in prediction of postoperative systemic inflammatory response syndrome (SIRS) after percutaneous nephrolithotomy (PCNL). White blood cell count is nonpredictive for urinary tract infection (UTI) in patients with acute renal colic. In patients with low risk for infectious complications, antibiotic prophylaxis during shock-wave lithotripsy (SWL) is unnecessary and single-dose antibiotics are comparably effective as prolonged antibiotic usage during PCNL and ureterorenoscopy (URS).Current findings support the American Urological Association (AUA) and European Association of Urology (EAU) guideline recommendations for a risk-adapted minimal antibiotic usage. Single-dose antibiotic prophylaxis is sufficient for low-risk PCNL and URS. For SWL no antibiotic prophylaxis is needed.

To summarize the recent literature on the topic of residual stone fragments in particular novel developments in this field.The urological position towards residual fragments has shifted in recent years from observation, to active retrieval with innovative methods, to algorithm-based predictions of surgical outcomes. Novel technologies have been described to extract residual fragments through magnetism, a polyethylene endoscopic pouch and a biocompatible stone adhesive. In an effort to have a tighter grip over the outcome of residual fragments, artificial neural networks (ANNs) have been developed to accurately predict surgical outcomes in terms of stone clearance and secondary procedures.Growing evidence continues to show the term clinically insignificant residual fragments (CIRF) for residual fragments of 4 mm or less to be a misnomer. In fact, only a third of CIRF is spontaneously cleared from the kidney after surgery and may become a cause for reintervention being both costly and significantly affecting patients' well being. Several novel methods which have been developed to extract residual fragments require further in-vivo investigations to confirm their safety and efficacy. ANNs algorithms are increasingly being used to predict surgical outcomes in stone therapy and assist in preoperative patient counselling and decision-making.

Purpose of review Traditionally, nephrolithiasis was considered a relative contraindication to kidney donation because of a risk of recurrent stones in donors and adverse stone-related outcomes in recipients. However, the scarcity of organs has driven the transplant community to re-examine and broaden selection criteria for living donors with stones. In this review, we summarize and contrast the guidelines published by various prominent national and international societies on this topic. Recent findings Although recent iterations of living donor guidelines are less stringent with respect to nephrolithiasis than those published in the 1990s, there is little consensus among national and international transplant society guidelines regarding selection criteria for potential kidney donors with nephrolithiasis. Summary The lack of evidence-based guidelines deters transplant centers from implementing selection criteria to accept donors with nephrolithiasis and discourages studies of outcomes in donors with nephrolithiasis and their recipients. In addition to drawing attention to the disparities in prevailing guidelines, we put forth several questions that must be answered before generalizable criteria for selection of donor with nephrolithiasis can be developed.

Purpose of review In the recent past, there were numerous and promising technological developments in the field of endourology leading to tremendous changes in the management of urolithiasis. This review will try to weave ancient stone therapy with the very modern advent of flexible ureteroscopy and recent developments in robotic systems. Recent findings In the broad field of flexible ureteroscopy for stone surgery, new disposable scopes have been developed and established. The use of robotic instruments is also a new and interesting concept. Additionally, clinical research on the understanding of laser features leads to a specific and appropriate use of lasers for lithotripsy, both holmium, and nowadays also interestingly thulium. Summary Disposable, digital flexible ureteroscopes for the treatment of both ureteric and kidney stones are taking an essential role in the medical field. Until recently, the clinically relevant laser systems for stone surgery during ureteroscopy are mainly based on Holmium laser YAG (Ho:YAG) devices, but a new thulium variant with promising features is giving interesting results. Additional research in laser features will guide to a better, more effective and safer treatment algorithm. Robotic technologies are promising but their definitive role still needs to be determined.

BACKGROUND AND OBJECTIVES: Idiopathic uric acid nephrolithiasis, which is closely associated with obesity and the metabolic syndrome, is increasing in prevalence. Unduly acidic urine pH, the quintessential pathophysiologic feature of this disease, is in part explained by inadequate excretion of the principal urinary buffer ammonium. The role of net acid excretion in the pathogenesis of uric acid nephrolithiasis is incompletely understood. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We compared acid-base parameters of patients with idiopathic uric acid nephrolithiasis with matched control subjects under controlled diets in an inpatient metabolic unit. Measurements included fasting blood and 24-hour urine chemistries and 24-hour urine metabolomic analysis. Comparisons between groups included analysis of covariance models controlling for urine pH or body mass index. RESULTS: Subjects with idiopathic uric acid nephrolithiasis had lower urine pH (5.5 versus 5.9; P

We prospectively assessed the efficacy and the predictors of the success of oral dissolution therapy by alkalization for lucent renal calculi.Patients with radiolucent renal stones were counseled to undergo oral dissolution therapy, which entails oral potassium citrate 20 mEq 3 times daily, 3 L daily fluid intake and a dietary regimen. The study primary end point was the achievement of a 6-month stone-free rate with oral dissolution therapy. The other end point was a change in stone surface area as measured by noncontrast computerized tomography at 3 and 6 months.Between February 2015 and January 2016 only 182 of the 212 eligible patients who agreed to participate were compliant with oral dissolution therapy and included in the final analysis. Mean stone surface area at enrollment was 1.3 cm (range 0.16 to 11.84). At 3 months 97 (53.2%), 65 (35.7%) and 20 (11.1%) patients were oral dissolution therapy responders (stone-free), partial responders and nonresponders, respectively. Oral dissolution therapy achieved a 6-month stone-free rate of 83%, including 97 and 54 patients after 3 and 6 months of oral dissolution therapy, respectively. On regression analysis the initial 3-month response to oral dissolution therapy (p = 0.001), lower stone density (p = 0.03) and higher urine pH 12 weeks after treatment (p = 0.01) independently predicted the oral dissolution therapy response at 6 months.Regardless of stone size, oral dissolution therapy was an effective treatment approach for lucent renal stones. The initial response to oral dissolution therapy after 3 months was the key factor in determining the potential oral dissolution therapy response after 6 months. In addition, treatment compliance in achieving the targeted urine pH and low stone density has an independent role in the oral dissolution therapy response.

Although urolithiasis affects each gender, conventional teaching proposes that men are 3 times more likely to have stones. However, clinical practice refutes such a disparity, particularly among working age adults. Small studies have suggested an erosion of this gender gap. Therefore, we examined the relationship between gender and stone prevalence among American adults younger than 50 years.We analyzed the NHANES (National Health and Nutrition Examination Survey) 2007 to 2012 cohort. Weighted proportions and multivariate logistic regression of the cohort and pertinent subgroups were assessed to determine the prevalence and the odds of nephrolithiasis.The cohort of 17,658 subjects, which was weighted to represent the American population of 218,828,951 adults, was 48.1% male. In our cohort of 8,888 adults weighted to represent 123,976,786 subjects younger than 50 years, which was 49.3% male and 50.7% female, there was no difference in stone prevalence (6.3% in males and 6.4% in females, p = 0.85). On unadjusted logistic regression of those younger than 50 years men were no more likely to report a stone history (OR 0.98, p = 0.85). Multivariate logistic regression adjusting for diabetes, obesity, ethnicity, age, and water, sodium and protein intake confirmed no difference in stone prevalence between the genders (OR 1.1, p = 0.51).Among adults of working and child rearing ages in the United States the much touted gender disparity in nephrolithiasis is not present. Prior assessments of gender based stone prevalence may have failed to specifically assess this economically critical demographic or there may in fact be an ongoing epidemiological change. Recognition that women are as likely as men to form stones in this cohort suggests the need to better elucidate the pathophysiology of stones in women.