Renal macrophages monitor and remove particles from urine to prevent tubule obstruction.

When the filtrate of the glomerulus flows through the renal tubular system, various microscopic sediment particles, including mineral crystals, are generated. Dislodging these particles is critical to ensuring the free flow of filtrate, whereas failure to remove them will result in kidney stone formation and obstruction. However, the underlying mechanism for the clearance is unclear. Here, using high-resolution microscopy, we found that the juxtatubular macrophages in the renal medulla constitutively formed transepithelial protrusions and "sampled" urine contents. They efficiently sequestered and phagocytosed intraluminal sediment particles and occasionally transmigrated to the tubule lumen to escort the excretion of urine particles. Mice with decreased renal macrophage numbers were prone to developing various intratubular sediments, including kidney stones. Mechanistically, the transepithelial behaviors of medulla macrophages required integrin ß1-mediated ligation to the tubular epithelium. These findings indicate that medulla macrophages sample urine content and remove intratubular particles to keep the tubular system unobstructed.

miR-148b-5p regulates hypercalciuria and calcium-containing nephrolithiasis.

Calcium-containing stones represent the most common form of kidney calculi, frequently linked to idiopathic hypercalciuria, though their precise pathogenesis remains elusive. This research aimed to elucidate the molecular mechanisms involved by employing urinary exosomal microRNAs as proxies for renal tissue analysis. Elevated miR-148b-5p levels were observed in exosomes derived from patients with kidney stones. Systemic administration of miR-148b-5p in rat models resulted in heightened urinary calcium excretion, whereas its inhibition reduced stone formation. RNA immunoprecipitation combined with deep sequencing identified miR-148b-5p as a suppressor of calcitonin receptor (Calcr) expression, thereby promoting urinary calcium excretion and stone formation. Mice deficient in Calcr in distal epithelial cells demonstrated elevated urinary calcium excretion and renal calcification. Mechanistically, miR-148b-5p regulated Calcr through the circRNA-83536/miR-24-3p signaling pathway. Human kidney tissue samples corroborated these results. In summary, miR-148b-5p regulates the formation of calcium-containing kidney stones via the circRNA-83536/miR-24-3p/Calcr axis, presenting a potential target for novel therapeutic interventions to prevent calcium nephrolithiasis.

The immune factors have complex causal regulation effects on kidney stone disease: a mendelian randomization study.

PURPOSE: Previous studies have reported the potential impact of immune cells on kidney stone disease (KSD), but definitive causal relationships have yet to be established. The purpose of this paper is to elucidate the potential causal association between immune cells and KSD by Mendelian randomization (MR) analysis. METHODS: In our study, a thorough two-sample Mendelian randomization (MR) analysis was performed by us to determine the potential causal relationship between immune cell traits and kidney stone disease. We included a total of four immune traits (median fluorescence intensity (MFI), relative cellular (RC), absolute cellular (AC), and morphological parameters (MP)), which are publicly available data. GWAS summary data related to KSD (9713 cases and 366,693 controls) were obtained from the FinnGen consortium. The primary MR analysis method was Inverse variance weighted. Cochran's Q test, MR Egger, and MR-Pleiotropy RESidual Sum and Outlier (MR-PRESSO) were used to assess the stability of the results. RESULTS: After FDR correction, the CD8 on HLA DR + CD8br (OR = 0.95, 95% CI = 0.93-0.98, p-value = 7.20 × 10- 4, q-value = 0.088) was determined to be distinctly associated with KSD, and we also found other 25 suggestive associations between immune cells and KSD, of which 13 associations were suggested as protective factors and 12 associations were suggested as risk factors. There was no horizontal pleiotropy or significant heterogeneity in our MR analysis, as determined by the p-value results of our Cochrane Q-test, MR Egger's intercept test, and MR-PRESSO, which were all > 0.05. CONCLUSIONS: Our study has explored the potential causal connection between immune cells and KSD by Mendelian randomization analysis, thus providing some insights for future clinical studies.

The Efficacy and Safety of Radiation-Free Retrograde Intrarenal Surgery: A Prospective Multicenter-Based, Randomized, Controlled Trial.

PURPOSE: Fluoroscopy is usually required during retrograde intrarenal surgery (RIRS). Although fluoroscopy is considered necessary for effective and safe RIRS, there is growing awareness regarding radiation exposure risk to patients and surgeons. We conducted a multicenter-based, randomized, controlled trial to compare the safety and effectiveness of radiation-free (RF) RIRS with radiation-usage (RU) RIRS for kidney stone management. MATERIALS AND METHODS: From August 2020 to April 2022, patients with a unilateral kidney stone (≤20 mm) eligible for RIRS were prospectively enrolled in 5 tertiary medical centers after randomization and divided into the RF and RU groups. RIRS was performed using a flexible ureteroscope with a holmium:YAG laser. The primary end point of this study was the success rate, defined as complete stone-free or residual fragments with asymptomatic kidney stones ≤ 3 mm. The secondary end point of this study was ascertaining the safety of RF RIRS. The success rates were analyzed using a noninferiority test. RESULTS: Of the 140 consecutive randomized participants, 128 patients completed this study (RF: 63; RU: 65). The success rates (78% vs 80%, P = .8) were not significantly different between the groups. The rate of high-grade (grade 2-4) ureter injury was not significantly higher in the RF group compared to the RU group (RF = 3 [4.8%] vs RU = 2 [3.1%], P = .6). In RF RIRS, the success rate was noninferior compared to RU RIRS (the difference was 2.2% [95% CI, 0.16-0.12]). CONCLUSIONS: This study demonstrated that the surgical outcomes of RF RIRS were noninferior to RU RIRS.

A Patient-Prioritized Research Agenda for Clinical Trials in Kidney Stone Disease.

PURPOSE: To ensure that research on kidney stones provides meaningful impact for the kidney stone community, patients and caregivers should be engaged as stakeholders in clinical trial design, starting at study inception. This project aimed to elicit, refine, and prioritize research ideas from kidney stone stakeholders to develop a patient-centered research agenda for clinical trials. MATERIALS AND METHODS: The Kidney Stone Engagement Core, a group of patients, caregivers, advocates, clinicians, and researchers, executed an iterative process of surveys and focus groups to elicit and refine research themes, which were then translated into research questions. A separate group of patients, caregivers, and clinicians prioritized these questions through parallel modified Delphi and crowd-sourced digital platforms. A research agenda was developed by the Kidney Stone Engagement Core based on the highest rated questions during a hybrid virtual/in-person capstone session. RESULTS: A total of 70 individuals (57 patients and caregivers, 13 researchers and clinicians) participated in the elicitation, 20 individuals (15 patients and caregivers, 5 researchers and clinicians) participated in refinement, and an additional 80 individuals (81 patients and caregivers, 9 researchers and clinicians) participated in prioritization. Key novel themes emerged from elicitation and refinement: ureteral stents, genetic evaluation, shared surgical decision-making, key subgroups, cumulative disease burden, genetic evaluation, and psychosocial support. Stakeholders generated 6 proposed trials from these themes focused on surveillance, surgical intervention, and medical prevention. CONCLUSIONS: Patients and caregivers valued comparative effectiveness kidney stone research that focused on individualized care, shared decision-making, and improvement of patient-reported experiences. This process provided actionable recommendations for future patient-centered clinical trials within kidney stone disease.

Intensity-Specific Physical Activity Measured by Accelerometer, Genetic Susceptibility, and the Risk of Kidney Stone Disease: Results From the UK Biobank.

RATIONALE & OBJECTIVE: Kidney stone disease (KSD), a significant health care problem within both developed and developing countries, has been associated with genetic risk factors. An association between physical activity and KSD risk also has been hypothesized, but studies have yielded inconsistent findings. This study investigated the association between the intensity of physical activity and the incidence of KSD accounting for genetic risk. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: A total of 80,473 participants from the UK Biobank Study. EXPOSURE: Physical activity levels, including total physical activity (TPA), moderate-to-vigorous intensity physical activity (MVPA), and light-intensity physical activity (LPA), were measured using accelerometers and quantified using a machine learning model. A polygenic risk score (PRS) for KSD was also constructed. OUTCOME: Individuals with KSD were identified using the International Classification of Diseases, Tenth Revision (ICD-10), and procedure codes for KSD surgery. ANALYTICAL APPROACH: A Fine and Gray survival model was used to estimate the associations of incident KSD with TPA, MVPA, LPA, and PRS (as categorical variables). Restricted cubic splines were used to examine potential nonlinear associations within the fully adjusted models. RESULTS: During an average follow-up of 6.19 years, 421 participants developed KSD. Participants in the highest quartiles of TPA, MVPA, and LPA had lower adjusted rates of KSD compared with those in the lowest quartiles: HR, 0.50 (95% CI, 0.44-0.56), 0.57 (95% CI, 0.51-0.64), and 0.66 (95% CI, 0.59-0.74), respectively. TPA, MVPA, and LPA were associated with a lower risk of KSD in participants with low and high genetic predisposition for KSD. LIMITATIONS: Selection bias as participants who provided accelerometry data may have been more adherent to health care. CONCLUSIONS: Physical activity was negatively associated with the risk of KSD, regardless of the genetic risk. Future large studies are warranted to confirm and explain the mechanisms underlying these associations. PLAIN-LANGUAGE SUMMARY: The association between the intensity of physical activity (PA) and the incidence of kidney stone disease (KSD) after accounting for genetic risk is unclear. We conducted a comprehensive prospective cohort study utilizing participants from the UK Biobank to assess the intensity of PA using accelerometers. Our study findings indicated that greater total PA, moderate-to-vigorous-intensity PA, and light-intensity PA were each associated with a lower risk of KSD irrespective of an individual's genetic risk. Our study informs the understanding of risk factors for KSD.

Mendelian randomization analysis reveals fresh fruit intake as a protective factor for urolithiasis.

OBJECTIVE: Previous studies have proposed that food intakes are associated with the risk of urolithiasis. Here, we conducted a two-sample Mendelian randomization (MR) study to evaluate the causal effects of different food intakes on urolithiasis. METHODS: Independent genetic variants associated with different food intakes at a genome-wide significant level were selected from summary-level statistics of genome-wide association studies from the UK Biobank. The association of these instrumental variables with urolithiasis was studied in a cohort from FinnGen Consortium. RESULTS: Among the 15 studied food intake exposures, tea intake (odds ratio [OR] = 0.433, 95% confidence interval [CI] = 0.281-0.667, p value = 1.470 × 10-4) and fresh fruit intake (OR = 0.358, 95% CI = 0.185-0.694, p value = 0.002) were found to significantly reduce the risk of the calculus of kidney and ureter. The association remained consistent in the sensitivity analyses. After adjusting for the effects of vitamin D and vitamin C, fresh fruit intake remained the reverse causal association with the calculus of kidney and ureter. CONCLUSIONS: Genetically proxied fresh fruit intake is causally associated with a reduced risk of the calculus of kidney and ureter.

Percutaneous nephrolithotomy vs retrograde intrarenal surgery for renal stones: a Cochrane Review.

OBJECTIVES: To assess the effects of percutaneous nephrolithotomy (PCNL) vs retrograde intrarenal surgery (RIRS) for the treatment of renal stones in adults. METHODS: We performed a comprehensive search of the Cochrane Library, MEDLINE, Embase, three other databases, trials registries, other sources of the grey literature, and conference proceedings up to 23 March 2023. We applied no restrictions on publication language or status. Screening, data extraction, risk-of-bias assessment, and certainty of evidence (CoE) rating using the Grading of Recommendations Assessment, Development and Evaluations (GRADE) approach were done in duplicate by two independent reviewers. This co-publication focuses on the primary outcomes of this review only. RESULTS: We included 42 trials that met the inclusion criteria. Stone-free rate (SFR): PCNL may improve SFRs (risk ratio [RR] 1.13, 95% confidence interval [CI] 1.08-1.18; I2 = 71%; 39 studies, 4088 participants; low CoE). Major complications: PCNL probably has little to no effect on major complications (RR 0.86, 95% CI 0.59-1.25; I2 = 15%; 34 studies, 3649; participants; moderate CoE) compared to RIRS. Need for secondary interventions: PCNL may reduce the need for secondary interventions (RR 0.31, 95% CI 0.17-0.55; I2 = 61%; 21 studies, 2005 participants; low CoE) compared to RIRS. CONCLUSION: Despite shortcomings in most studies that lowered our certainty in the estimates of effect to mostly very low or low, we found that PCNL may improve SFRs and reduce the need for secondary interventions while not impacting major complications. Ureteric stricture rates may be similar compared to RIRS. We expect the findings of this review to be helpful for shared decision-making about management choices for individuals with renal stones.

The impact of kidney stone disease on quality of life in high-risk stone formers.

OBJECTIVE: To assess the impact of kidney stone disease (KSD) and its treatment on the health-related quality of life (HRQOL) of high-risk stone formers with hyperparathyroidism, renal tubular acidosis, malabsorptive disease, and medullary sponge kidney. PATIENTS AND METHODS: The Wisconsin Stone Quality of Life questionnaire was used to evaluate HRQOL in 3301 patients with a history of KSD from 16 institutions in North America between 2014 and 2020. Baseline characteristics and medical history were collected from patients, while active KSD was confirmed through radiological imaging. The high-risk group was compared to the remaining patients (control group) using the Wilcoxon rank-sum test. RESULTS: Of 1499 patients with active KSD included in the study, the high-risk group included 120 patients. The high-risk group had significantly lower HRQOL scores compared to the control group (P < 0.01). In the multivariable analyses, medullary sponge kidney disease and renal tubular acidosis were independent predictors of poorer HRQOL, while alkali therapy was an independent predictor of better HRQOL (all P < 0.01). CONCLUSIONS: Among patients with active KSD, high-risk stone formers had impaired HRQOL with medullary sponge kidney disease and renal tubular acidosis being independent predictors of poorer HRQOL. Clinicians should seek to identify these patients earlier as they would benefit from prompt treatment and prevention.

Exploring optimal settings for safe and effective thulium fibre laser lithotripsy in a kidney model.

OBJECTIVES: To explore the optimal laser settings and treatment strategies for thulium fibre laser (TFL) lithotripsy, namely, those with the highest treatment efficiency, lowest thermal injury risk, and shortest procedure time. MATERIALS AND METHODS: An in vitro kidney model was used to assess the efficacy of TFL lithotripsy in the upper calyx. Stone ablation experiments were performed on BegoStone phantoms at different combinations of pulse energy (EP ) and frequency (F) to determine the optimal settings. Temperature changes and thermal injury risks were monitored using embedded thermocouples. Experiments were also performed on calcium oxalate monohydrate (COM) stones to validate the optimal settings. RESULTS: High EP /low F settings demonstrated superior treatment efficiency compared to low EP /high F settings using the same power. Specifically, 0.8 J/12 Hz was the optimal setting, resulting in a twofold increase in treatment efficiency, a 39% reduction in energy expenditure per unit of ablated stone mass, a 35% reduction in residual fragments, and a 36% reduction in total procedure time compared to the 0.2 J/50 Hz setting for COM stones. Thermal injury risk assessment indicated that 10 W power settings with high EP /low F combinations remained below the threshold for tissue injury, while higher power settings (>10 W) consistently exceeded the safety threshold. CONCLUSIONS: Our findings suggest that high EP /low F settings, such as 0.8 J/12 Hz, are optimal for TFL lithotripsy in the treatment of COM stones. These settings demonstrated significantly improved treatment efficiency with reduced residual fragments compared to conventional settings while keeping the thermal dose below the injury threshold. This study highlights the importance of using the high EP /low F combination with low power settings, which maximizes treatment efficiency and minimizes potential thermal injury. Further studies are warranted to determine the optimal settings for TFL for treating kidney stones with different compositions.

Biology of calcium homeostasis regulation in intestine and kidney.

Calcium (Ca2+) is an essential divalent cation involved in many bodily functions including bone composition, cell growth and division, blood clotting, and muscle contraction. The bone, intestine, and kidneys are important to the maintenance of Ca2+ homeostasis. Ninety-nine percent of body Ca2+ is stored in the skeleton as hydroxyapatite. The small, and to a lesser extent the large intestine absorbs Ca2+ from the diet. Once in the circulation, Ca2+ is filtered by the glomerulus and the majority, >95%, is reabsorbed along the nephron. The remainder is excreted in the urine. Two general (re)absorptive pathways contribute to the vectorial transport of Ca2+ across renal and intestinal epithelia: 1) a paracellular pathway, which is reliant on claudins in the tight junction of epithelium and the electrochemical gradient and 2) a transcellular pathway, which requires different influx, intracellular buffering/shuttling and basolateral efflux mechanisms, to actively transport Ca2+ across the epithelial cell. Blood Ca2+ levels are maintained by hormones including parathyroid hormone, 1,25-dihydroxyvitamin D3, fibroblast growth factor 23 and through effects of Ca2+-sensing receptor (CaSR) signaling. Disruption of Ca2+ homeostasis can result in altered blood Ca2+ levels and/or hypercalciuria, the latter is a phenomenon closely linked to the formation of kidney stones. Genetic alterations affecting renal Ca2+ handling can cause hypercalciuria, an area of expanding investigation. This review explores the molecular mechanisms governing Ca2+ homeostasis by the intestine and kidneys and discusses clinical aspects of genetic disorders associated with Ca2+-based kidney stone disease.

The relationship between stone-free and patient position in retrograde intrarenal surgery: a randomized prospective study.

PURPOSE: Residual fragments not removed with urinary stone surgery may become symptomatic. In this context, this study was carried out to investigate the effect of performing retrograde intrarenal surgery, which is conventionally performed in the lithotomy position, in the modified lithotomy position (Trend-side) on stone-free rates following the surgery. METHODS: This prospective study consisted of 100 patients with a single kidney stone smaller than 2 cm between 2021 and 2023. These patients were randomized into two groups of 50 patients each to be operated on in the conventional lithotomy and Trend-side positions. Variables were compared using independent t test for continuous variables and chi-square test for categorical variables. RESULTS: There was no significant difference between the lithotomy and Trend-side position groups in terms of preoperative size, density, location of the stone, and hydronephrosis degree. Stone-free rate was 72% (n = 36) in the lithotomy group and 92% (n = 46) in the Trend-side group. Hence, there was a significant difference between the groups in the stone-free rate in favor of the Trend-side group (p = 0.009). Fragmentation time was statistically significantly shorter in the Trend-side group than in the lithotomy group (34 ± 17 min vs. 43 ± 14 min; p = 0.006). There was no significant difference between the groups in postoperative complication rates. CONCLUSION: Performing retrograde intrarenal surgery in the Trend-side position shortened the duration of fragmentation compared to the lithotomy position and was associated with higher stone-free rates. In conclusion, the Trend-side position can be safely preferred in patients undergoing retrograde intrarenal surgery due to kidney stones.

Cumulative sum analysis of the learning curve for retrograde intrarenal stone surgery in newbie surgeons.

INTRODUCTION: This study investigated the learning curve of retrograde intrarenal surgery (RIRS) in patients with medium-sized stones using cumulative sum analysis (CUSUM) to evaluate the competence and proficiency of three new surgeons during their first RIRS procedures. MATERIALS AND METHODS: We conducted a retrospective review of 227 patients from 2019 to 2022 at a single institution. The patients were divided into four groups based on the operating surgeon: tutor surgeon (85 patients), newbie surgeon A (21 patients), newbie surgeon B (85 patients), and newbie surgeon C (36 patients). Patients had one or multiple stones with the largest stone diameter fell within the range of 10-30 mm. Fragmentation efficacy was calculated as "removed stone volume (mm3) divided by operative time (minutes)." CUSUM analysis monitored changes in fragmentation efficacy and validated surgical outcomes. RESULTS: No statistically significant differences were observed in the total stone volume, maximum stone size, or total operation time between the three newbie surgeons and the tutor surgeon. The mean fragmentation efficacy value was comparable among the newbie surgeons, but significantly different from that of the tutor surgeon. The minimum acceptable fragmentation efficacy level was set at 25.12 mL/min, based on the tutor's average value. The CUSUM curves for the three surgeons initially remained relatively flat until Cases 12-15, after which they increased and eventually plateaued. Stone-free rates and postoperative complications did not differ significantly among the surgeons. CONCLUSION: Learning curve analysis for the three newbie surgeons indicated that approximately 12-15 cases were required to reach a plateau.

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.

Higher oxidative balance score is associated with lower kidney stone disease in US adults: a population-based cross-sectional study.

PURPOSE: Oxidative balance stress (OBS) was an important indicator for assessing exposure to oxidative stress related to diet and lifestyle. The purpose of this study was to explore the relationship between OBS and kidney stone disease (KSD). METHODS: Secondary dataset analysis was performed by the study from six survey cycles (2007-2018) in the National Health and Nutrition Examination Survey (NHANES). OBS was the exposure factor and ever had kidney stone (yes or no) was the outcome. Weighted univariate or multivariate logistic regression models were used to estimate the associations. RESULTS: The prevalence of KSD among participants was 8.6%. OBS showed a significant negative correlation with KSD (OR: 0.98, 95% CI 0.96-0.999), 35% reduction in KSD in the highest OBS quartile compared to the lowest OBS quartile. Dietary OBS was significantly negatively correlated with KSD (OR: 0.98, 95% CI 0.96-0.9998), but not with lifestyle OBS. In addition, OBS had a negative correlation with KSD in females (OR: 0.97, 95% CI 0.94-0.996), non-diabetic participants (OR: 0.98, 95% CI 0.96-0.99), and hypertensive participants (OR: 0.96, 95% CI 0.93-0.99), but OBS was not observed to be associated with KSD in gout participants. Interestingly, this relationship existed in participants aged 30-60 years and a ratio of family income to poverty (PIR) of 1.3-3.5 (all P value < 0.05). CONCLUSION: Our study revealed that OBS was negative associated with KSD, and high OBS might be a protective factor in KSD. Targeting one of the components of OBS might be beneficial.

Predictive markers for infections after extracorporeal shockwave lithotripsy in patients with kidney stone based on a large prospective cohort.

OBJECTIVE: Infections in patients with kidney stones after extracorporeal shockwave lithotripsy (SWL) is a common clinical issue. However, the associated factors are unclear. Therefore, we aim to develop and validate a predictive model for infections after SWL in patients with kidney stone. METHODS: Between June 2020 and May 2022, consecutive kidney stone patients were enrolled. Of them, 553 patients comprised the development cohort. One hundred sixty-five patients comprised the validation cohort. The data were prospectively collected. The stepwise selection was applied using the likelihood ratio test with Akaike's information criterion as the stopping rule; A predictive model was constructed through multivariate logistic regression. The performance was evaluated regarding discrimination, calibration, and clinical usefulness. RESULTS: Predictors of infections after SWL in treating kidney stones included older age (OR = 1.026, p = 0.041), female (OR = 2.066, p = 0.039), higher BMI (OR = 1.072, p = 0.039), lower stone density (OR = 0.995, p < 0.001), and higher grade of hydronephrosis (OR = 5.148, p < 0.001). For the validation cohort, the model showed good discrimination with an area under the receiver operating characteristic curve of 0.839 (95% CI 0.736, 0.941) and good calibration. Decision curve analysis demonstrated that the model was also clinically useful. CONCLUSION: This study indicated that age, gender, BMI, stone density, and hydronephrosis grade were significant predictors of infections after SWL in treating kidney stones. It provided evidence in optimizing prevention and perioperative treatment strategies to reduce the risk of infection after SWL.

Percutaneous nephrolithotomy for adult renal transplant de novo graft lithiasis: a single center analysis and systematic review of the literature.

INTRODUCTION/OBJECTIVE: Graft stones in renal transplant recipients pose a unique challenge, finding effective interventions to ensure optimal graft function and patient well-being. Various methods of stone clearance have been described for graft stones, including percutaneous nephrolithotomy (PCNL). While PCNL is a promising approach for managing graft stones, specific outcomes and associated characteristics for this approach have not been comprehensively evaluated before. This study aims to evaluate the safety and efficacy of the use of PCNL as the primary intervention of graft stones by assessing stone-free rates (SFR), treatment impact on graft function, and perioperative complications. METHODS: A retrospective clinical audit was performed for all transplants performed in a single center from 2007 to 2022, which included all graft lithiasis patients who were treated with PCNL. Both perioperative parameters and post-operative outcomes were collected. In addition, a systematic review including articles from MEDLINE, Embase, Web of Science yielded 18 full-text articles published between 1/1/2000 and 15/11/2023. The results pertaining to patients who underwent PCNLs for graft stones were cross-referenced and thoroughly evaluated. The review encompassed a comprehensive analysis of clinical data, postoperative outcomes, and procedural details. The protocol for the systematic review was prospectively registered on PROSPERO (CRD42023486825). RESULTS: In our center, 6 graft lithiasis patients were treated with PCNL. The initial SFR was 83.3%. SFR at 3 months and 1 year were both 100.0%. SFR at 3 years was 66.7%. Other centers reported initial SFR of 82.6-100.0% (interquartile range). SFR at 3 months, 1 year, 3 years was not well reported across the included studies. Incidence of graft lithiasis ranged from 0.44%-2.41%. Most common presentations at diagnosis were oliguria/anuria/acute kidney injury and asymptomatic. Reported complications included blood loss, transient hematuria, high urine output, sepsis, and damage to surrounding structures. The most commonly reported metabolic abnormalities in transplant lithiasis patients included hyperuricemia and hyperparathyroidism. CONCLUSION: PCNL is a practical and efficient choice for addressing graft lithiasis, demonstrating excellent stone clearance and minimal perioperative complications. These findings show the importance of PCNL as a primary intervention in this complex patient population.

Comparison of automated kidney stone size measurement and volumetry in photon counting CT compared to 3rd generation dual energy CT and physically measurements - an ex vivo study.

PURPOSE: This ex vivo study aimed to compare a newly developed dual-source photon-counting CT (PCCT) with a 3rd generation dual-source dual-energy CT (DECT) for the detection and measurement (stone lengths and volumetrics) of urinary stones. METHODS: 143 urinary stones with a known geometry were physically measured and defined as reference values. Next, urinary stones were placed in an anthropomorphic abdomen-model and were scanned with DECT and PCCT. Images were read by two experienced examiners and automatically evaluated using a specific software. RESULTS: DECT and PCCT showed a high sensitivity for manual stone detection of 97.9% and 94.4%, and for automatic detection of 93.0% and 87.4%, respectively. Compared to that uric acid and xanthine stones were recognized slightly worse by DECT and PCCT with manual stone detection (93.3% and 82.2%), and with automatic detection (77.8% and 60.0%). All other stone entities were completely recognized. By comparing the maximum diameter of the reference value and DECT, Pearson-correlation was 0.96 (p < 0.001) for manual and 0.97 (p < 0.001) for automatic measurement, and for PCCT it was 0.94 (p < 0.001) for manual and 0.97 (p < 0.001) for automatic measurements. DECT and PCCT can also reliably determine volume manually and automatically with a Pearson-correlation of 0.99 (p < 0.001), respectively. CONCLUSION: Both CTs showed comparable results in stone detection, length measurement and volumetry compared to the reference values. Automatic measurement tends to underestimate the maximum diameter. DECT proved to be slightly superior in the recognition of xanthine and uric acid stones.

Association of serum soluble α­klotho with risk of kidney stone disease: a population-based cross-sectional study.

BACKGROUND: The aim of the study was to explore the association of serum soluble klotho with kidney stone disease (KSD) in the general population over the age of 40 years in the United States. METHODS: We integrated the data in National Health and Nutrition Examination Survey from 2007 to 2016 years. The relationship between serum soluble α­klotho and prevalence of KSD was analyzed by constructing weighted multivariable logistic regression model, restricted cubic spline (RCS) curve, and subgroup analyses. RESULTS: In the study, a total of 13,722 individuals were included in our study. A U-shaped association between serum soluble klotho and the risk of KSD was shown by the RCS curve (P value for nonlinear < 0.05). In the full adjusted model, compared with the lowest quartile of serum soluble α­klotho, the adjusted odd ratios (95% confidence intervals) for KSD across the quartiles were (0.999 (0.859, 1.164), 1.005 (0.858, 1.176), and 1.061 (0.911, 1.235)). Subgroup analyses also showed that the U-shaped association of serum soluble α­klotho with KSD was found among subjects who were age < 60 years, female or male, with or without hypertension, and BMI ≥ 30 kg/m2. CONCLUSIONS: Our findings suggested that serum klotho levels had a U-shaped correlation with risk of KSD. When the Klotho level is at 818.66 pg/mL, prevalence of KSD is lowest. Therefore, maintaining a certain level of serum soluble α­klotho could prevent the occurrence of KSD.

Is "Kidney Stone Calculator" efficient in predicting ureteroscopic lithotripsy duration? A holmium:YAG and thulium fiber lasers comparative analysis.

PURPOSE: This study aimed to evaluate the ability of Kidney Stone Calculator (KSC), a flexible ureteroscopy surgical planning software, to predict the lithotripsy duration with both holmium:YAG (Ho:YAG) and thulium fiber laser (TFL). METHODS: A multicenter prospective study was conducted from January 2020 to April 2023. Patients with kidney or ureteral stones confirmed at non-contrast computed tomography and treated by flexible ureteroscopy with laser lithotripsy were enrolled. "Kidney Stone Calculator" provided stone volume and subsequent lithotripsy duration estimation using three-dimensional segmentation of the stone on computed tomography and the graphical user interface for laser settings. The primary endpoint was the quantitative and qualitative comparison between estimated and effective lithotripsy durations. Secondary endpoints included subgroup analysis (Ho:YAG-TFL) of differences between estimated and effective lithotripsy durations and intraoperative outcomes. Multivariate analysis assessed the association between pre- and intraoperative variables and these differences according to laser source. RESULTS: 89 patients were included in this study, 43 and 46 in Ho:YAG and TFL groups, respectively. No significant difference was found between estimated and effective lithotripsy durations (27.37 vs 28.36 min, p = 0.43) with a significant correlation (r = + 0.89, p < 0.001). Among groups, this difference did not differ (p = 0.68 and 0.07, respectively), with a higher correlation between estimated and effective lithotripsy durations for TFL compared to Ho:YAG (r = + 0.95, p < 0.001 vs r = + 0.81, p < 0.001, respectively). At multivariate analysis, the difference was correlated with preoperative (volume > 2000 mm3 (Ho:YAG), 500-750 mm3 SV and calyceal diverticulum (TFL)), operative (fragmentation setting (p > 0.001), and basket utilization (p = 0.05) (Ho:YAG)) variables. CONCLUSION: KSC is a reliable tool for predicting the lithotripsy duration estimation during flexible ureteroscopy for both Ho:YAG and TFL. However, some variables not including laser source may lead to underestimating this estimation.