Sex-specific Stone-forming Phenotype in Mice During Hypercalciuria/Urine Alkalinization.

Sex differences in kidney stone formation are well known. Females generally have slightly acidic blood and higher urine pH when compared with males, which makes them more vulnerable to calcium stone formation, yet the mechanism is still unclear. We aimed to examine the role of sex in stone formation during hypercalciuria and urine alkalinization through acetazolamide and calcium gluconate supplementation, respectively, for 4 weeks in wild-type (WT) and moderately hypercalciuric [TRPC3 knockout [KO](-/-)] male and female mice. Our goal was to develop calcium phosphate (CaP) and CaP+ calcium oxalate mixed stones in our animal model to understand the underlying sex-based mechanism of calcium nephrolithiasis. Our results from the analyses of mice urine, serum, and kidney tissues show that female mice (WT and KO) produce more urinary CaP crystals, higher [Ca2+], and pH in urine compared to their male counterparts. We identified a sex-based relationship of stone-forming phenotypes (types of stones) in our mice model following urine alkalization/calcium supplementation, and our findings suggest that female mice are more susceptible to CaP stones under those conditions. Calcification and fibrotic and inflammatory markers were elevated in treated female mice compared with their male counterparts, and more so in TRPC3 KO mice compared with their WT counterparts. Together these findings contribute to a mechanistic understanding of sex-influenced CaP and mixed stone formation that can be used as a basis for determining the factors in sex-related clinical studies.

Patterns of weight change during adulthood and incidence of nephrolithiasis: a population-based study.

BACKGROUND: There is some evidence to suggest that there may be a link between body mass index (BMI) and the development of kidney stones, it remains unclear whether weight change was associated with the presence of kidney stone. AIMS: The objective of this study was to investigate the potential association between changes patterns in weight during adulthood and the incidence of kidney stone. METHODS: This study included 14472 participants aged 30-75 years, whose BMI was recorded at both baseline and 10 years prior to the survey. We categorized individuals into five weight change patterns: stable healthy, non-obesity to obesity, obesity to non-obesity, stable obesity, and maximum overweight. Odds ratios (OR) and 95% confidence intervals (CI) relating weight change to incident kidney stone were calculated using logistic regression models adjusting for covariates. The non-linear association between absolute weight change was investigated using the restricted cubic spline (RCS) regression. The supposed population attributable fraction (PAF) for the weight change patterns was calculated. RESULTS: After adjusting for all confounders, participants changing from non-obesity to obesity, obesity to non-obesity, and stable obesity had significantly higher risks of kidney stone than those with healthy weight during adulthood (OR = 1.59, 95% CI:1.18-2.13; OR = 1.78, 95% CI: 1.47-2.16; OR = 1.80, 95% CI: 1.48-2.19, respectively). A U-shaped association was observed, and the risk of kidney stone was lowest in participants with stable healthy BMI. If the population had maintained a healthy BMI, a 28.7% (95% CI: 18.6%-37.5%) lower incidence of kidney stones was observed. CONCLUSIONS: This study found that changes in weight during adulthood are linked to the risk of developing kidney stones. Maintaining healthy weight during adulthood is important for reducing the risk of developing kidney stones.

Climate change and kidney stones.

PURPOSE OF REVIEW: Kidney stones affect an increasing proportion of the population. We suggest that these trends are in part influenced by exposure to higher temperatures as a result of climate change and urbanization. The changing epidemiology of kidney stones is a topic worthy of discussion due to the economic and healthcare burden the condition poses as well as the quality-of-life disruption faced by individuals with kidney stones. RECENT FINDINGS: The relationship between heat and kidney stones is well supported. Exposure to high temperatures has been shown to increase risk for stone development within a short time frame. Effects are modified by factors such as sex, comorbid conditions, and population vulnerability and adaptability. Urban heat islands (UHIs) likely exaggerate the effect of increasing global surface temperature. The concentration of UHIs often coincides with historic redlining practices in the United States, potentially contributing to observed disparities in kidney health among minoritized populations. As global surface temperature increases and urbanization trends continue, a greater proportion of the world's population is exposed to significant temperature extremes each year, leading to the expectation that kidney stone prevalence will continue to increase. SUMMARY: This work describes the effect of increasing global surface temperature as a result of climate change on kidney stone disease and kidney health. These effects may result in further perpetuation of significant kidney stone related social disparities. We suggest strategies to mitigate the effects of heat exposure on stone formation.

Play it safe: renal function after bilateral flexible ureteroscopy for kidney stones.

PURPOSE: We searched for perioperative renal function deterioration risk factors in patients that underwent bilateral flexible ureteroscopy (fURS) for kidney stones. METHODS: From August 2016 to February 2020, symptomatic patients > 18 years old with bilateral kidney stones up to 20 mm in each side were prospectively studied. Serum creatinine samples were collected on admission to surgery, immediate postoperative (IPO), on POD 3, 10, and 30. Estimated glomerular filtration rate (eGFR) was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) without a race coefficient. RESULTS: Thirty patients underwent bilateral fURS. Comparing to preoperative eGFR, median IPO and POD3 eGFR (p < 0.001) were significantly lower, and POD10 (p = 0.092) and POD30 (p = 0.648) were similar to preoperative eGFR. During follow-up, 22/30 (73.3%), 14/30 (46.7%), and 7/30 (23.3%) of the patients presented a decrease > 10% eGFR, > 20% eGFR, and > 30% eGFR, respectively. Multivariate analysis demonstrated that lower preoperative eGFR is a risk factor for eGFR < 60 mL/min/1.73 m2, p = 0.019 [1.021-1.263; 1.136]; ASA > 1 is a risk factor for decrease of eGFR > 10%, p = 0.028 [1.25-51.13; 8.00]; longer operative time is a risk factor for decrease of eGFR > 20%, p = 0.042 [1.00-1.05; 1.028]; and operative time ≥ 120 min is a risk factor for decrease of eGFR > 30%, p = 0.026 [0.016-0.773; 0.113]. CONCLUSIONS: Renal function suffers a reversible decrease after bilateral fURS. Our study suggests that adequate selection of patients and maintaining operative time < 120 min are relevant factors in preventing acute renal function deterioration following bilateral fURS.

Ureteral stent after PCNL: is leaving the threads through the percutaneous tract safe and better tolerated?

OBJECTIVE: To assess safety, urinary symptoms, and feasibility of JJ stent removal with exteriorized threads through the percutaneous tract after percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: Prospective, transversal, comparative, experimental, randomized 1-to-1 cohort study in 52 patients who underwent "tubeless" PCNL from October 2020 to November 2022. Group A with threads through the urethra and Group B through the percutaneous tract. The validated USSQ (Ureteral Stent Symptom Questionnaire) was applied in the Urology office a week after the procedure, and the JJ stent was withdrawn by pulling the threads. Hemoglobin and urine culture, and pre- and post-surgery were evaluated. RESULTS: There is a statistically significant difference in favor of group B when comparing urinary symptoms (p = 0.008), body pain (p = 0.009), and general condition (p = 0.042), mainly for non-urgency incontinence, frequency of analgesic use, and dysuria. There were significant differences between groups (p = 0.028, p = 0.026, p = 0.027, respectively). There is no association with urinary infections (p = 0.603) nor an increased risk of bleeding (p = 0.321). CONCLUSION: The removal of the JJ stent with exteriorized threads through the percutaneous tract after PCNL in the office is a feasible and safe procedure if it is removed before 8 days and has better tolerance regarding the urinary symptoms.

Ureteral wall thickness as a predictor for non-invasive treatment success for steinstrasse. Can we save time?

PURPOSE: We aimed to define factors affecting the non-invasive overall treatment success (medical expulsive therapy (MET) ± shock wave lithotripsy (SWL)) for uncomplicated ureteral steinstrasse (SS) clearance. METHODS: We retrospectively evaluated consecutive patients who underwent SWL for renal stones between 2017 and 2021. Patients with uncomplicated SS were included. All patient's demographic and radiological data, e.g., age, gender, pre-SWL stenting, SS site, type, leading stone size in widest diameter (< 10 mm and ≥ 10 mm), ureteral wall thickness (UWT) in mm against the leading stone were collected. If SS was diagnosed, medical treatment was given for 4 weeks. In case of MET failure, either SWL for the leading stones + MET or direct URS was done. Non-invasive treatment success (SFR) was considered if complete clearance of SS occurred with no complications or the need for invasive intervention. RESULTS: A total of 145 patients were included with mean age of 45.9 ± 12.4 years. SFR in case of MET only occurred in 27.9%. Complications happened in 26 patients (17.9%). Non-invasive treatment SFR was achieved in 78 patients (53.8%) totally where SS type I, leading stone size ≤ 10 mm type and decreased UWT around the leading stone increased treatment success. CONCLUSION: Ureteral wall thickness is an important factor predicting SS management success. Besides the decreased UWT, non-invasive management should be offered for type I SS with leading stone ≤ 10 mm.

Natural history of urine and plasma oxalate in children with primary hyperoxaluria type 1.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is a rare, severe genetic disease causing increased hepatic oxalate production resulting in urinary stone disease, nephrocalcinosis, and often progressive chronic kidney disease. Little is known about the natural history of urine and plasma oxalate values over time in children with PH1. METHODS: For this retrospective observational study, we analyzed data from genetically confirmed PH1 patients enrolled in the Rare Kidney Stone Consortium PH Registry between 2003 and 2018 who had at least 2 measurements before age 18 years of urine oxalate-to-creatinine ratio (Uox:cr), 24-h urine oxalate excretion normalized to body surface area (24-h Uox), or plasma oxalate concentration (Pox). We compared values among 3 groups: homozygous G170R, heterozygous G170R, and non-G170R AGXT variants both before and after initiating pyridoxine (B6). RESULTS: Of 403 patients with PH1 in the registry, 83 met the inclusion criteria. Uox:cr decreased rapidly over the first 5 years of life. Both before and after B6 initiation, patients with non-G170R had the highest Uox:cr, 24-h Uox, and Pox. Patients with heterozygous G170R had similar Uox:cr to homozygous G170R prior to B6. Patients with homozygous G170R had the lowest 24-h Uox and Uox:cr after B6. Urinary oxalate excretion and Pox tend to decrease over time during childhood. eGFR over time was not different among groups. CONCLUSIONS: Children with PH1 under 5 years old have relatively higher urinary oxalate excretion which may put them at greater risk for nephrocalcinosis and kidney failure than older PH1 patients. Those with homozygous G170R variants may have milder disease. A higher resolution version of the Graphical abstract is available as Supplementary information.

Comparison of percutaneous nephrolithotomy and flexible ureterorenoscopy in the treatment of single upper ureteral calculi measuring 1 to 2 centimeters: a retrospective study.

PURPOSE: To compare the efficacy and safety of micropercutaneous nephrolithotomy (MPCNL) and flexible ureteroscopy (FURS) in the treatment of single upper ureteral calculi measuring 1 to 2 centimeters. METHODS: This study is a retrospective analysis that combines a review of medical records with an outcomes management database. A total of 163 patients who underwent MPCNL and 137 patients who had FURS were identified between January 2017 and December 2021. Demographic data, operation time, hospitalization time, stone-free rate, and complication rate were collected and analyzed. RESULTS: Preoperative general data of sex, age, BMI, serum creatinine, time of stone existence, stone hardness, stone diameter, preoperative hydronephrosis, and preoperative infection of the MPCNL group have no statistically significant difference with that of the FURS group. All MPCNL or FURS operations in both groups were successfully completed without any instances of reoperation or conversion to another surgical procedure. Patients who underwent MPCNL had a considerably reduced operation time (49.6 vs. 72.4 min; P<0.001), but a higher duration of hospitalization (9.1 vs. 3.9 days; P<0.001) compared to those who underwent FURS. The stone-free rate in the MPCNL group was superior to that of the FURS group, with a percentage of 90.8% compared to 71.5% (P<0.001). There was no statistically significant disparity in the rate of complications between the two groups (13.5% vs. 15.3%; P = 0.741). CONCLUSION: Both MPCNL and FURS are viable and secure surgical choices for individuals with solitary upper ureteral calculi measuring 1 to 2 cm. The FURS procedure resulted in a shorter duration of hospitalization compared to MPCNL. However, it had a comparatively lower rate of successfully removing the stones and required a longer duration for the operation.There were no substantial disparities observed in the complication rate between the two groups.FURS is the preferable option for treating uncomplicated upper ureteral calculi, whereas MPCNL is the preferable option for treating complicated upper ureteral calculi.Prior to making treatment options, it is crucial to take into account the expertise of surgeons, the quality of the equipment, and the preferences of the patient. TRIAL REGISTRATION: No.

Association between oxidative balance score and kidney stones: data from the national health and nutrition examination survey (NHANES).

PURPOSE: Some studies have found that the pathological formation of kidney stones is closely related to injury and inflammatory response. Behaviors such as dietary composition, physical activity, obesity and smoking can all affect the body's oxidative stress levels. In order to evaluate the effects of various diets and lifestyles on the body's oxidative and antioxidant systems, an oxidative balance score was developed. To investigate whether the OBS is associated with the development of kidney stones. METHODS: Data were taken from the National Health and Nutrition Examination Survey (NHANES) from 2007-2018, followed by retrospective observational studies. The association between kidney stones and OBS was analyzed using survey-weighted logistic regression by adjusting for demographics, laboratory tests, and medical comorbidity covariates. The oxidative balance score is calculated by screening 16 nutrients and 4 lifestyle factors, including 5 prooxidants and 15 antioxidants, based on prior information about the relationship between oxidation levels in the body and nutrients or lifestyle factors. RESULTS: A total of 26,786 adult participants were included in the study, of which 2,578, or 9.62%, had a history of nephrolithiasis. Weighted logistic regression analysis found an association between OBS and kidney stones. In the fully tuned model, i.e., model 3, the highest quartile array of OBS was associated with the lowest quartile array of OBS (OR = 0.73 (0.57, 0.92)) with the risk of kidney stone (p = 0.01), and was statistically significant and remained relatively stable in each model. At the same time, the trend test in the model is also statistically significant. With the increase of OBS, the OR value of kidney stones generally tends to decrease. CONCLUSIONS: There is an inverse correlation between OBS and kidney stone disease. At the same time, higher OBS suggests that antioxidant exposure is greater than pro-oxidative exposure in diet and lifestyle, and is associated with a lower risk of kidney stones.

Association between drinking status and risk of kidney stones among United States adults: NHANES 2007-2018.

OBJECTIVE: This study aimed to investigate the relationship between drinking status and kidney stones occurrence among United States (US) adults who consume alcohol. METHODS: We conducted a cross-sectional analysis using data from the National Health and Nutrition Examination Survey (NHANES 2007-2018). Questionnaires yielded information on alcohol consumption and kidney health. Drinking status was categorized into four groups-former, mild, moderate, and heavy-based on alcohol consumption patterns. The aim was to explore the relationship between drinking status and the prevalence of kidney stones occurrence. For this analysis, we examined a group of individuals diagnosed with kidney stones. With survey weights applied, the total weight of the group was 185,690,415. RESULTS: We used logistic regression to measure the relationship between drinking status and the likelihood of developing kidney stones. In a fully adjusted model, former drinkers were less likely to have previously experienced kidney stones (OR 0.762, 95% CI 0.595-0.977, P < 0.05). In subgroup analysis, heavy alcohol consumption was associated with a significantly reduced likelihood of kidney stones occurrence in various populations. The adjusted odds ratios (with 95% confidence intervals) of kidney stones risk for heavy alcohol consumption were 0.745 (0.566-0.981) for young individuals, 0.566 (0.342-0.939) for older individuals, 0.708 (0.510-0.981) for individuals of white race, 0.468 (0.269-0.817) for individuals with underweight/normal BMI, 0.192 (0.066-0.560) for widowed people, 0.538 (0.343-0.843) for smoking individuals, 0.749 (0.595-0.941) for individuals without a cancer history, and 0.724 (0.566-0.925) for individuals without a stroke history. CONCLUSIONS: In US adults who consume alcohol, a negative linear relationship is apparent between drinking status and the prevalence of kidney stones, with heavy drinking showing a lower prevalence compared to former drinkers. However, the causal relationship between drinking status and kidney stones requires further investigation in future research endeavors.

Kidney stones and dietary intake in adults: a population-based study in southwest Iran.

BACKGROUND: The prevalence of kidney stones is on the rise globally. Several risk factors, including lifestyle, contribute to the formation of kidney stones. Nevertheless, there is a contentious debate about the relationship between diet and kidney stones. Therefore, our study aimed to assess the relationship between macronutrients and micronutrients and the formation of kidney stones. METHODS: This population-based cross-sectional study was conducted in the baseline phase of the Hoveyzeh Cohort Study, focusing on adults aged 35-70 in southwest Iran. The information on demographic characteristics, anthropometrics, kidney stone history, and food frequency was collected. Chi-square and t-tests were utilized to assess the relationship between categorical and numerical variables with kidney stones. The ANCOVA and logistic regression models were used to evaluate the relationships while controlling for confounding factors. RESULTS: Among 10,009 participants, the overall prevalence of kidney stones was 18.77% (95% CI: 17.99-19.53). A higher intake of carbohydrates [OR = 1.02 (95% CI:1.002-1.03), p = 0.026] and copper [OR = 1.04 (95% CI:1.01-1.09), p = 0.025] were found to be associated with kidney stones. No associations were found between the other assessed macronutrients or micronutrients and kidney stones (p-tvalues > 0.05). CONCLUSION: Our study's findings indicate a correlation between diet and the formation of kidney stones. However, the relationship between dietary factors and kidney stones is complex, and further research is needed.

Central Adiposity Increases Risk of Kidney Stone Disease through Effects on Serum Calcium Concentrations.

SIGNIFICANCE STATEMENT: Kidney stone disease is a common disorder with poorly understood pathophysiology. Observational and genetic studies indicate that adiposity is associated with an increased risk of kidney stone disease. However, the relative contribution of general and central adipose depots and the mechanisms by which effects of adiposity on kidney stone disease are mediated have not been defined. Using conventional and genetic epidemiological techniques, we demonstrate that general and central adiposity are independently associated with kidney stone disease. In addition, one mechanism by which central adiposity increases risk of kidney stone disease is by increasing serum calcium concentration. Therapies targeting adipose depots may affect calcium homeostasis and help to prevent kidney stone disease. BACKGROUND: Kidney stone disease affects approximately 10% of individuals in their lifetime and is frequently recurrent. The disease is linked to obesity, but the mechanisms mediating this association are uncertain. METHODS: Associations of adiposity and incident kidney stone disease were assessed in the UK Biobank over a mean of 11.6 years/person. Genome-wide association studies and Mendelian randomization (MR) analyses were undertaken in the UK Biobank, FinnGen, and in meta-analyzed cohorts to identify factors that affect kidney stone disease risk. RESULTS: Observational analyses on UK Biobank data demonstrated that increasing central and general adiposity is independently associated with incident kidney stone formation. Multivariable MR, using meta-analyzed UK Biobank and FinnGen data, established that risk of kidney stone disease increases by approximately 21% per one standard deviation increase in body mass index (BMI, a marker of general adiposity) independent of waist-to-hip ratio (WHR, a marker of central adiposity) and approximately 24% per one standard deviation increase of WHR independent of BMI. Genetic analyses indicate that higher WHR, but not higher BMI, increases risk of kidney stone disease by elevating adjusted serum calcium concentrations (ß=0.12 mmol/L); WHR mediates 12%-15% of its effect on kidney stone risk in this way. CONCLUSIONS: Our study indicates that visceral adipose depots elevate serum calcium concentrations, resulting in increased risk of kidney stone disease. These findings highlight the importance of weight loss in individuals with recurrent kidney stones and suggest that therapies targeting adipose depots may affect calcium homeostasis and contribute to prevention of kidney stone disease.

Pathophysiology and Main Molecular Mechanisms of Urinary Stone Formation and Recurrence.

Kidney stone disease (KSD) is one of the most common urological diseases. The incidence of kidney stones has increased dramatically in the last few decades. Kidney stones are mineral deposits in the calyces or the pelvis, free or attached to the renal papillae. They contain crystals and organic components, and they are made when urine is supersaturated with minerals. Calcium-containing stones are the most common, with calcium oxalate as the main component of most stones. However, many of these form on a calcium phosphate matrix called Randall's plaque, which is found on the surface of the kidney papilla. The etiology is multifactorial, and the recurrence rate is as high as 50% within 5 years after the first stone onset. There is a great need for recurrence prevention that requires a better understanding of the mechanisms involved in stone formation to facilitate the development of more effective drugs. This review aims to understand the pathophysiology and the main molecular mechanisms known to date to prevent recurrences, which requires behavioral and nutritional interventions, as well as pharmacological treatments that are specific to the type of stone.

The Rise in Tubular pH during Hypercalciuria Exacerbates Calcium Stone Formation.

In calcium nephrolithiasis (CaNL), most calcium kidney stones are identified as calcium oxalate (CaOx) with variable amounts of calcium phosphate (CaP), where CaP is found as the core component. The nucleation of CaP could be the first step of CaP+CaOx (mixed) stone formation. High urinary supersaturation of CaP due to hypercalciuria and an elevated urine pH have been described as the two main factors in the nucleation of CaP crystals. Our previous in vivo findings (in mice) show that transient receptor potential canonical type 3 (TRPC3)-mediated Ca2+ entry triggers a transepithelial Ca2+ flux to regulate proximal tubular (PT) luminal [Ca2+], and TRPC3-knockout (KO; -/-) mice exhibited moderate hypercalciuria and microcrystal formation at the loop of Henle (LOH). Therefore, we utilized TRPC3 KO mice and exposed them to both hypercalciuric [2% calcium gluconate (CaG) treatment] and alkalineuric conditions [0.08% acetazolamide (ACZ) treatment] to generate a CaNL phenotype. Our results revealed a significant CaP and mixed crystal formation in those treated KO mice (KOT) compared to their WT counterparts (WTT). Importantly, prolonged exposure to CaG and ACZ resulted in a further increase in crystal size for both treated groups (WTT and KOT), but the KOT mice crystal sizes were markedly larger. Moreover, kidney tissue sections of the KOT mice displayed a greater CaP and mixed microcrystal formation than the kidney sections of the WTT group, specifically in the outer and inner medullary and calyceal region; thus, a higher degree of calcifications and mixed calcium lithiasis in the kidneys of the KOT group was displayed. In our effort to find the Ca2+ signaling pathophysiology of PT cells, we found that PT cells from both treated groups (WTT and KOT) elicited a larger Ca2+ entry compared to the WT counterparts because of significant inhibition by the store-operated Ca2+ entry (SOCE) inhibitor, Pyr6. In the presence of both SOCE (Pyr6) and ROCE (receptor-operated Ca2+ entry) inhibitors (Pyr10), Ca2+ entry by WTT cells was moderately inhibited, suggesting that the Ca2+ and pH levels exerted sensitivity changes in response to ROCE and SOCE. An assessment of the gene expression profiles in the PT cells of WTT and KOT mice revealed a safeguarding effect of TRPC3 against detrimental processes (calcification, fibrosis, inflammation, and apoptosis) in the presence of higher pH and hypercalciuric conditions in mice. Together, these findings show that compromise in both the ROCE and SOCE mechanisms in the absence of TRPC3 under hypercalciuric plus higher tubular pH conditions results in higher CaP and mixed crystal formation and that TRPC3 is protective against those adverse effects.

Intraoperative computed tomography for detection of residual stones in endourology procedures: systematic review and meta-analysis.

BACKGROUND: Success rates in endourological procedures, notably percutaneous nephrolithotomy (PCNL) and ureteroscopy (URS), have demonstrated suboptimal outcomes, leading to more reinterventions and radiation exposure. Recently, the use of intraoperative computed tomography (ICT) scans has been hypothesized as a promising solution for improving outcomes in endourology procedures. With this considered, we conducted a comprehensive systematic review and meta-analysis encompassing all available studies that evaluate the impact of the use of intraoperative CT scans on surgical outcomes compared to conventional fluoroscopic-guided procedures. METHODS: This systematic review was conducted in accordance with PRISMA guidelines. Multiple databases were systematically searched up to December of 2023. This study aimed to directly compare the use of an ICT scan with the standard non-ICT-guided procedure. The primary endpoint of interest was success rate, and the secondary endpoints were complications and reintervention rates, while radiation exposure was also evaluated. Data extraction and quality assessment were performed following Cochrane recommendations. Data was presented as an Odds ratio with 95%CI across trials and a random-effects model was selected for pooling of data. RESULTS: A comprehensive search yielded 533 studies, resulting in the selection of 3 cohorts including 327 patients (103 ICT vs 224 in non-ICT). Primary outcome was significantly higher in the experimental group versus the control group (84.5% vs 41.4% respectively, 307 patients; 95% CI [3.61, 12.72]; p<0.00001; I2=0). Reintervention rates also decreased from 32.6% in the control to 12.6% in the ICT group (OR 0.34; 95%CI [0.12,0.94]; p =0.04; I2= 48%), whereas complication rates did not exhibit significant differences. Radiation exposure was also significantly reduced in two of the included studies. CONCLUSION: This meta-analysis highlights a favorable outcome with intraoperative CT scan use in PCNL procedures, showing a considerable increase in SFR when compared to standard fluoroscopy and nephroscopy. Despite limited studies, our synthesis underscores the potential of ICT scans to significantly reduce residual stones and their consequences for endourology patients, as reinterventions and follow-up ionizing radiation studies.

Characterization of Stone Events in Patients With Type 3 Primary Hyperoxaluria.

PURPOSE: Hallmarks of primary hyperoxaluria type 3 are nephrolithiasis and hyperoxaluria. However, little is known about factors influencing stone formation in this disease. We characterized stone events and examined associations with urine parameters and kidney function in a primary hyperoxaluria type 3 population. MATERIALS AND METHODS: We retrospectively analyzed clinical, and laboratory data of 70 primary hyperoxaluria type 3 patients enrolled in the Rare Kidney Stone Consortium Primary Hyperoxaluria Registry. RESULTS: Kidney stones occurred in 65/70 primary hyperoxaluria type 3 patients (93%). Among the 49 patients with imaging available, the median (IQR) number of stones was 4 (2, 5), with largest stone 7 mm (4, 10) at first imaging. Clinical stone events occurred in 62/70 (89%) with median number of events per patient 3 (2, 6; range 1-49). Age at first stone event was 3 years (0.99, 8.7). Lifetime stone event rate was 0.19 events/year (0.12, 0.38) during follow-up of 10.7 (4.2, 26.3) years. Among 326 total clinical stone events, 139 (42.6%) required surgical intervention. High stone event rates persisted for most patients through the sixth decade of life. Analysis was available for 55 stones: pure calcium oxalate accounted for 69%, with mixed calcium oxalate and phosphate in 22%. Higher calcium oxalate supersaturation was associated with increased lifetime stone event rate after adjusting for age at first event (IRR [95%CI] 1.23 [1.16, 1.32]; P < .001). By the fourth decade, estimated glomerular filtration rate was lower in primary hyperoxaluria type 3 patients than the general population. CONCLUSIONS: Stones impose a lifelong burden on primary hyperoxaluria type 3 patients. Reducing urinary calcium oxalate supersaturation may reduce event frequency and surgical intervention.

Outcomes of Flexible Ureteroscopy vs Extracorporeal Shock Wave Lithotripsy for Renal Stones in Pediatric Patients: A European Association of Urology Urolithiasis Guidelines Systematic Review and Meta-Analysis.

PURPOSE: We sought to determine which treatment between flexible ureteroscopy and shock wave lithotripsy has a better stone-free rate in pediatric patients (<18 years) with renal or proximal ureteric stones (<2 cm). Subanalysis for all outcomes for randomized controlled trials only. MATERIALS AND METHODS: Using PubMed, Web of Science, and the Cochrane database, we identified studies (randomized clinical trials and prospective comparative nonrandomized studies) published until August 2022 reporting surgical outcomes of pediatrics patients undergoing flexible ureteroscopy and shock wave lithotripsy with renal or proximal ureteric stones <2 cm (PROSPERO ID: CRD42022378790). Only randomized controlled trials were considered for meta-analysis. Stone-free rate, operative time, and complications were analyzed. Analysis was performed in R. RESULTS: A total of 6 studies identified, of which 3 were randomized clinical trials and 4 had data on renal stones. A total of 669 patients were analyzed. Mean age ranged from 4.4 to 12.4 years. The shock wave lithotripsy group presented a range of stone-free rate between 21 and 90% while the flexible ureteroscopy group presented a range of stone-free rates between 37% and 97%. Meta-analysis of randomized controlled trials only (n=302) demonstrated significantly higher stone-free rate in flexible ureteroscopy vs shock wave lithotripsy (RR = 1.17, 95% CI: 1.04-1.33, P = 0.01), operative time (mean difference = +16.4 minutes, 95% CI: 7.3-25.5, P < 0.01) and hospital stay (mean difference = +0.25 days, 95% CI: 0.14-0.36, P < 0.001). But no difference in fluoroscopy exposure time (mean difference = -21.0 seconds, 95% CI: -42.6 to 0.56, P = 0.07), Clavien I-II (RR = 1.23, 95% CI: 0.71-2.12, P = 0.45) or Clavien III-V complications (RR = 1.04, 95% CI: 0.32-3.42, P = 0.95). CONCLUSIONS: Flexible ureteroscopy has a significantly higher stone-free rate than shock wave lithotripsy, with no difference in complication rate or fluoroscopy exposure time, and significantly higher operative times and hospital stay. However, the current evidence base for this is weak and further randomized trials are needed.

What Is the Optimal Stenting Duration After Ureteroscopy and Stone Intervention? Impact of Dwell Time on Postoperative Emergency Department Visits.

PURPOSE: AUA stone management guidelines recommend stenting duration following ureteroscopy be minimized to reduce morbidity; stents with extraction strings may be used for this purpose. However, an animal study demonstrated that short dwell time results in suboptimal ureteral dilation, and a pilot clinical study showed this increases postprocedure events. Using real-world practice data we examined stent dwell time after ureteroscopy and its association with postoperative emergency department visits. MATERIALS AND METHODS: We used the Michigan Urological Surgery Improvement Collaborative registry to identify ureteroscopy and stenting procedures (2016-2019). Pre-stented cases were excluded. Stenting cohorts with and without strings were analyzed. Using multivariable logistic regression we evaluated the risk of an emergency department visit occurring on the day of, or day after, stent removal based on dwell time and string status. RESULTS: We identified 4,437 procedures; 1,690 (38%) had a string. Median dwell time was lower in patients with a string (5 vs 9 days). Ureteroscopy in younger patients, smaller stones, or renal stone location had a higher frequency of string use. The predicted probability of an emergency department visit was significantly greater in procedures with string, compared to without string, when dwell times were less than 5 days (P < .01) but were not statistically significant after. CONCLUSIONS: Patients who had ureteroscopy and stenting with a string have short dwell times. Patients are at increased risk of a postoperative emergency department visit around the time of stent removal if dwell time is ≤4 days. We recommended stenting duration of at least 5 days in nonpre-stented patients.

Bone loss and kidney stone risk in weightlessness.

PURPOSE OF REVIEW: Weightlessness increases both bone loss and kidney stone formation risk. The large interior volume of the International Space Station (ISS) has allowed for a mix of exercise devices to help maintain the skeleton. But space exploration is changing. Long stays on the ISS will be replaced by journeys in smaller spacecraft both to and around the Moon. Small private space stations are under development. This will limit the ability to do exercise countermeasures, which can increase both bone loss and kidney stone risk. This review examines this risk and how it can be minimized in this new era of spaceflight. RECENT FINDINGS: Simple, low-mass, low-power ways to track bone loss and kidney stone risk in space are being researched. Tracking urinary calcium concentration in the first morning void and targeting additional countermeasures (e.g. bisphosphonates) to those who run consistently high levels is one promising approach. SUMMARY: New exploration spacecraft would not have the room and capability to replicate the current 2 h, daily exercise countermeasure programme on the ISS. A monitoring approach, perhaps using urinary calcium as a marker, is needed to find those at greatest risk. This would allow countermeasures to be targeted individually and used efficiently.

Redlining has led to increasing rates of nephrolithiasis in minoritized populations: a hypothesis.

PURPOSE OF REVIEW: The persistent rise in kidney stone prevalence in recent decades has prompted much speculation as to the causes. There has been some discussion about the effect of heat on nephrolithiasis. Here, we review recent data and postulate that heat may play a role in stone formation on a large scale and among African-Americans in particular. RECENT FINDINGS: African-Americans are the race/ancestry group with faster rates of increasing incidence and prevalence of kidney stones. We make the observation that urban heat islands in the United States have resulted in part from the effects of redlining, a practice of systematic segregation and racism in housing that led to the development of neighborhoods with substantial disparities in environmental conditions. SUMMARY: In this thought experiment, we propose that the disproportionate rise in the prevalence of nephrolithiasis in minoritized populations correlates with increased temperatures specifically in neighborhoods adversely affected by the practice of redlining. We discuss phenomena in support of this hypothesis and ongoing work to test this theory.