Epidemiology of Kidney Stones

Low serum testosterone is associated with an increased risk of first-time renal calculi in men without testosterone replacement therapy

The incidence of low serum testosterone has been increasing in men of all ages across a period which also corresponds to an increasing prevalence of kidney stones. Currently, the relationship between testosterone and kidney stones is unclear. Using the TriNetX Research Network, we performed a retrospective cohort study to evaluate the risk of developing an initial kidney stone in men based on their total testosterone level. Men aged ≥18 were divided into a low testosterone (<300 ng/dL) and normal testosterone (≥ 300 ng/dL) cohort. Men were excluded if they had a history of a kidney stone encounter diagnosis before testosterone measurement and a history of testosterone therapy prescription at any point. Propensity score matching was employed with an absolute standardized mean difference of less than 0.1 used as an indicator of successful matching. Our main outcome of interest was risk of developing an initial kidney stone in men aged ≥18 and within age-based subgroups. In men 18 and older, low testosterone was associated with a higher risk of one or more kidney stone encounter diagnoses (HR 1.12, 95% CI [1.09-1.15]). When stratified by age, no significant association between low testosterone and kidney stone encounter diagnoses was seen in men aged 18-24 (HR 1.09, 95% CI [0.85-1.39]). The highest risk was observed in men with low testosterone aged 34-44 (HR 1.29, 95% CI [1.17-1.38]). In this study, low serum testosterone was associated with an increased risk of initial kidney stone diagnosis in adult men without testosterone therapy prescriptions at any point in their life. Stratifying by age, the increased risk appears to begin in men aged 25, with the highest observed risk in men aged 33-44.

Can Artificial Intelligence Accurately Detect Urinary Stones? A Systematic Review

Objectives: To perform a systematic review on artificial intelligence (AI) performances to detect urinary stones. Methods: A PROSPERO-registered (CRD473152) systematic search of Scopus, Web of Science, Embase, and PubMed databases was performed to identify original research articles pertaining to AI stone detection or measurement, using search terms ("automatic" OR "machine learning" OR "convolutional neural network" OR "artificial intelligence" OR "detection" AND "stone volume"). Risk-of-bias (RoB) assessment was performed according to the Cochrane RoB tool, the Joanna Briggs Institute Checklist for nonrandomized studies, and the Checklist for Artificial Intelligence in Medical Imaging (CLAIM). Results: Twelve studies were selected for the final review, including three multicenter and nine single-center retrospective studies. Eleven studies completed at least 50% of the CLAIM checkpoints and only one presented a high RoB. All included studies aimed to detect kidney (5/12, 42%), ureter (2/12, 16%), or urinary (5/12, 42%) stones on noncontrast computed tomography (NCCT), but 42% intended to automate measurement. Stone distinction from vascular calcification interested two studies. All studies used AI machine learning network training and internal validation, but a single one provided an external validation. Trained networks achieved stone detection, with sensitivity, specificity, and accuracy rates ranging from 58.7% to 100%, 68.5% to 100%, and 63% to 99.95%, respectively. Detection Dice score ranged from 83% to 97%. A high correlation between manual and automated stone volume (r = 0.95) was noted. Differentiate distal ureteral stones and phleboliths seemed feasible. Conclusions: AI processes can achieve automated urinary stone detection from NCCT. Further studies should provide urinary stone detection coupled with phlebolith distinction and an external validation, and include anatomical abnormalities and urologic foreign bodies (ureteral stent and nephrostomy tubes) cases.

Causal associations between 45 dietary intake habits and urolithiasis: insights from genetic studies

Background

Different dietary habits can have varying effects on human health and metabolism, and these can be intervened and regulated. Kidney stones, as a disease caused by multiple factors, are largely attributed to diet and metabolism, but the potential causal relationship with dietary intake habits remains unclear. Therefore, this study aims to link the predicted dietary intake based on 45 genetic factors with urolithiasis and explore the potential causal relationship.

Methods

We extracted complete genome-wide association studies (GWASs) data on 45 dietary intake traits from the UK Biobank study. Data on kidney stones were obtained from the FinnGen database. In both univariable and multivariable Mendelian randomization analyses, we used inverse variance weighted (IVW) as the primary method to calculate P values, odds ratios (ORs), and 95% confidence intervals (CIs). We examined result heterogeneity using Cochran's Q test. We also carefully investigated potential sources of horizontal pleiotropy using the Mendelian randomization (MR)-PRESSO and MR-Egger methods, and conducted linkage disequilibrium score regression (LDSC) analysis on the corrected P values.

Results

Through univariable analysis, we identified 11 dietary habits that potentially causally associate with kidney stones among the 45 examined traits, including 9 protective factors and 2 risk factors. Based on the corrected results with false discovery rate (FDR) and sensitivity analysis, we found one relatively robust evidence. We controlled for common stone risk factors, such as body mass index and smoking, as confounders in multivariable analysis, and no significant results were observed after controlling for these confounders. Based on the LDSC analysis, most of the evidence supports significant genetic correlations with urolithiasis among the 11 traits with potential causal associations.

Conclusions

This study confirms the impact of certain dietary factors on the development of kidney stones. Our findings contribute to providing evidence for dietary adjustments in daily life or dietary guidance specifically targeting kidney stone patients.

The predictive ability of Mayo adhesive probability score for evaluating intraoperative bleeding in standard percutaneous nephrolithotomy in adult patients

Mayo adhesive probability (MAP) score is one of the commonest tool to predict the adherence status of perirenal fat. The association between MAP score and intraoperative hemorrhage in patients undergoing micropercutaneous nephrolithotomy was comfirmed in a recent well designed study. We aimed to investigate if MAP score may predict the possibility for significant intraoperative bleeding in supine percutaneous nephrolithotomy (PCNL) performed with a 26 Fr rigid nephroscope. In this observational retrospective study, demographic, clinical, laboratory, radiological, perioperative (operation duration, hospitalization, intraoperative bleeding, success) and MAP score (perinephric fat stranding, posterior perinephric fat thickness and total MAP score) data of all patients who underwent supine PCNL between June 2021 and July 2023 were evaluated. The patients were divided into 2 groups according to their MAP scores (79 [54.1%] patients with MAP score < 3 [low MAP score] and 67 [54.1%] patients with MAP score ≥ 3 [high MAP score]). The rate of patients with intraoperative bleeding was 47.8% in the patient group with a high MAP score, while it was 22.8% in the patient group with a low MAP score (p = 0.002). In multivariate logistic regression analysis, anticoagulant drug use history (OR = 2.525; 95% CI = 1.025-6.224; p = 0.044), presence of multiple stones (OR = 3.015; 95% CI = 1.205-7.543; p = 0.018), calyx localization of the stone (OR = 2.871;95% CI = 1.166-7.068; p = 0.022), higher renal parenchymal thickness (OR = 1.119; 95% CI = 1.049-1.193; p = 0.001) and MAP score > 3 (OR = 3.486; 95% CI = 1.579-7.696; p = 0.002) were defined as independent risk factors for significant intraoperative bleeding. In clinical practice, the MAP score can be used to predict bleeding before PCNL.

Dietary Sodium and Potassium Intakes and Kidney Stone Prevalence: The National Health and Nutrition Examination Survey 2011-2018

The associations between dietary sodium intake (DSI), dietary potassium intake (DPI), and kidney stone disease (KSD) are not clear. We examined The National Health and Nutrition Examination Survey 2011-2018 to determine the independent associations between daily DSI, DPI, DSI/DPI, and KSD prevalence. In total, 19,405 participants were included for analysis, of which 1,895 had KSD. Higher DSI was not associated with increased odds of KSD in regression analysis when DSI was modeled as a continuous variable (OR = 0.99, 95% CI: 0.99-1.00, p = 0.2), or when comparing highest quartile of DSI to lowest quartile (OR = 0.84, 95% CI: 0.68-1.04, p = 0.1). Unlike DSI, higher DPI was strongly associated with reduced odds of KSD in regression analysis when DPI was modeled as a continuous variable (OR = 0.99, 95% CI: 0.99-0.99, p = 0.02), or when comparing highest quartile of DPI to lowest quartile (OR = 0.75, 95% CI: 0.60-0.94, p = 0.01). Lastly, higher DSI/DPI was also strongly associated with increased odds of KSD in regression analysis when DSI/DPI was modeled as a continuous variable (OR = 1.1, 95% CI: 1.01-1.20, p = 0.03), or when comparing highest quartile of DPI to lowest quartile (OR = 1.30, 95% CI: 1.10-1.70, p = 0.008). All the observed relationships were independent of total calorie intake. In conclusion, both lower DPI and higher DSI/DPI are associated with an increased risk of KSD. Future prospective studies are needed to clarify these causal relationships.

Management of urinary stones: state of the art and future perspectives by experts in stone disease

AIM

To present state of the art on the management of urinary stones from a panel of globally recognized urolithiasis experts who met during the Experts in Stone Disease Congress in Valencia in January 2024. Options of treatment: The surgical treatment modalities of renal and ureteral stones are well defined by the guidelines of international societies, although for some index cases more alternative options are possible. For 1.5 cm renal stones, both m-PCNL and RIRS have proven to be valid treatment alternatives with comparable stone-free rates. The m-PCNL has proven to be more cost effective and requires a shorter operative time, while the RIRS has demonstrated lower morbidity in terms of blood loss and shorter recovery times. SWL has proven to be less effective at least for lower calyceal stones but has the highest safety profile. For a 6mm obstructing stone of the pelviureteric junction (PUJ) stone, SWL should be the first choice for a stone less than 1 cm, due to less invasiveness and lower risk of complications although it has a lower stone free-rate. RIRS has advantages in certain conditions such as anticoagulant treatment, obesity, or body deformity. Technical issues of the surgical procedures for stone removal: In patients receiving antithrombotic therapy, SWL, PCN and open surgery are at elevated risk of hemorrhage or perinephric hematoma. URS, is associated with less morbidity in these cases. An individualized combined evaluation of risks of bleeding and thromboembolism should determine the perioperative thromboprophylactic strategy. Pre-interventional urine culture and antibiotic therapy are mandatory although UTI treatment is becoming more challenging due to increasing resistance to routinely applied antibiotics. The use of an intrarenal urine culture and stone culture is recommended to adapt antibiotic therapy in case of postoperative infectious complications. Measurements of temperature and pressure during RIRS are vital for ensuring patient safety and optimizing surgical outcomes although techniques of measurements and methods for data analysis are still to be refined. Ureteral stents were improved by the development of new biomaterials, new coatings, and new stent designs. Topics of current research are the development of drug eluting and bioresorbable stents. Complications of endoscopic treatment: PCNL is considered the most invasive surgical option. Fever and sepsis were observed in 11 and 0.5% and need for transfusion and embolization for bleeding in 7 and 0.4%. Major complications, as colonic, splenic, liver, gall bladder and bowel injuries are quite rare but are associated with significant morbidity. Ureteroscopy causes less complications, although some of them can be severe. They depend on high pressure in the urinary tract (sepsis or renal bleeding) or application of excessive force to the urinary tract (ureteral avulsion or stricture). Diagnostic work up:  Genetic testing consents the diagnosis of monogenetic conditions causing stones. It should be carried out in children and in selected adults. In adults, monogenetic diseases can be diagnosed by systematic genetic testing in no more than 4%, when cystinuria, APRT deficiency, and xanthinuria are excluded. A reliable stone analysis by infrared spectroscopy or X-ray diffraction is mandatory and should be associated to examination of the stone under a stereomicroscope. The analysis of digital images of stones by deep convolutional neural networks in dry laboratory or during endoscopic examination could allow the classification of stones based on their color and texture. Scanning electron microscopy (SEM) in association with energy dispersive spectrometry (EDS) is another fundamental research tool for the study of kidney stones. The combination of metagenomic analysis using Next Generation Sequencing (NGS) techniques and the enhanced quantitative urine culture (EQUC) protocol can be used to evaluate the urobiome of renal stone formers. Twenty-four hour urine analysis has a place during patient evaluation together with repeated measurements of urinary pH with a digital pH meter. Urinary supersaturation is the most comprehensive physicochemical risk factor employed in urolithiasis research. Urinary macromolecules can act as both promoters or inhibitors of stone formation depending on the chemical composition of urine in which they are operating. At the moment, there are no clinical applications of macromolecules in stone management or prophylaxis. Patients should be evaluated for the association with systemic pathologies.

PROPHYLAXIS

Personalized medicine and public health interventions are complementary to prevent stone recurrence. Personalized medicine addresses a small part of stone patients with a high risk of recurrence and systemic complications requiring specific dietary and pharmacological treatment to prevent stone recurrence and complications of associated systemic diseases. The more numerous subjects who form one or a few stones during their entire lifespan should be treated by modifications of diet and lifestyle. Primary prevention by public health interventions is advisable to reduce prevalence of stones in the general population. Renal stone formers at "high-risk" for recurrence need early diagnosis to start specific treatment. Stone analysis allows the identification of most "high-risk" patients forming non-calcium stones: infection stones (struvite), uric acid and urates, cystine and other rare stones (dihydroxyadenine, xanthine). Patients at "high-risk" forming calcium stones require a more difficult diagnosis by clinical and laboratory evaluation. Particularly, patients with cystinuria and primary hyperoxaluria should be actively searched.

FUTURE RESEARCH

Application of Artificial Intelligence are promising for automated identification of ureteral stones on CT imaging, prediction of stone composition and 24-hour urinary risk factors by demographics and clinical parameters, assessment of stone composition by evaluation of endoscopic images and prediction of outcomes of stone treatments. The synergy between urologists, nephrologists, and scientists in basic kidney stone research will enhance the depth and breadth of investigations, leading to a more comprehensive understanding of kidney stone formation.

Urinary stone analysis and clinical characteristics of 496 patients in Taiwan

Evaluate urinary stone components' epidemiological features in urolithiasis individuals and explore potential correlations between stone components and patients' clinical characteristics. A retrospective analysis of urinary stone compositions in 496 patients from a northern Taiwan medical center (February 2006 to October 2021) was conducted. We investigated associations between sex, age, body mass index (BMI), hypertension, diabetes mellitus (DM), hyperlipidemia (HLP), gout, coronary artery disease (CAD), cerebral vascular accident (CVA), chronic kidney disease (CKD), habits, urine pH, and three main stone groups: calcium oxalate (CaOx), calcium phosphate (CaP), and uric acid (UA). Males accounted for 66.5% of cases, with a male-to-female ratio of 1.99:1. Males were negatively associated with CaP stones (OR 0.313, p < 0.001) and positively with UA stones (OR 2.456, p = 0.009). Age showed a negative correlation with CaOx stones (OR 0.987, p = 0.040) and a positive correlation with UA stones (OR 1.023, p < 0.001). DM had a protective effect against CaP stones (OR 0.316, p = 0.004). Gout had a positive association with UA stones (OR 2.085, p = 0.035). Smoking was adversely associated with UA stones (OR 0.350, p = 0.018). Higher urine pH was a risk factor for CaP stones (OR 1.641, p = 0.001) and a protective factor against UA stones (OR 0.296, p < 0.001). These results may provide insights into the pathogenesis of urinary stones and the development of preventative strategies for high-risk populations. Further research is required to confirm and expand upon these findings.

The Multidisciplinary Approach in the Management of Patients with Kidney Stone Disease-A State-of-the-Art Review

Kidney stone disease has a multifactorial etiology, and evolving dietary habits necessitate continuous updates on the impact of dietary components on lithogenesis. The relationship between diseases influenced by lifestyle, such as obesity and diabetes, and kidney stone risk underscores the need for comprehensive lifestyle analysis. Effective management of kidney stones requires a multidisciplinary approach, involving collaboration among nutritionists, urologists, nephrologists, and other healthcare professionals to address the complex interactions between diet, lifestyle, and individual susceptibility. Personalized dietary therapy, based on each patient's unique biochemical and dietary profile, is essential and necessitates comprehensive nutritional assessments. Accurate dietary intake evaluation is best achieved through seven-day, real-time dietary records. Key factors influencing urinary risk include fluid intake, dietary protein, carbohydrates, oxalate, calcium, and sodium chloride. Personalized interventions, such as customized dietary changes based on gut microbiota, may improve stone prevention and recurrence. Current research suggests individualized guidance on alcohol intake and indicates that tea and coffee consumption might protect against urolithiasis. There is potential evidence linking tobacco use and secondhand smoke to increased kidney stone risk. The effects of vitamins and physical activity on kidney stone risk remain unresolved due to mixed evidence. For diseases influenced by lifestyle, conclusive evidence on targeted interventions for nephrolithiasis prevention is lacking, though preliminary research suggests potential benefits. Management strategies emphasize lifestyle modifications to reduce recurrence risks, support rapid recovery, and identify predisposing conditions, highlighting the importance of these changes despite inconclusive data.

Recurrent Urinary Stone Formers: Imaging Assessment and Endoscopic Treatment Strategies: A Systematic Search and Review

Background/Objectives: Nephrolithiasis is a heterogeneous disease with a high prevalence and recurrence rate. Although there has been much progress regarding the surgical treatment of stones, a standardized follow-up, especially in recurrent stone formers (SFs), has yet to be decided. This fact leads to the overuse of computed tomography (CT) scans and many reoperations in patients, thus increasing their morbidity and the financial burden on the health systems. This review systematically searched the literature for original articles regarding imaging strategies and endoscopic treatment for patients with recurrent urolithiasis, aiming to identify optimal strategies to deal with these patients. Methods: We systematically searched the Medline database (accessed on 1 April 2024) for articles regarding imaging modalities and endoscopic treatment for patients with recurrent urinary tract lithiasis. Results: No specific follow-up or endoscopic treatment strategy exists for patients with recurrent urolithiasis. CT scan was the imaging modality most used in the studies, followed by X-ray, ultrasonography, and digital tomosynthesis. A transparent algorithm could not be identified. Percutaneous nephrolithotomy (PCNL), retrograde intrarenal surgery (RIRS), and ureteroscopy (URS) were used in the studies for endoscopic treatment. PCNL showed the best stone-free (SFr) rate and lowest hazard ratio (HR) for reoperation. RIRS showed superiority over extracorporeal shockwave lithotripsy for recurrent SFs, but fragments over 4 mm increased the recurrent rate. URS has an increased HR for reoperation for bilateral stones. Conclusions: The heterogeneity of urolithiasis leaves urologists without a standardized plan for recurrent SFs. Thus, each patient's follow-up should be planned individually and holistically. Pre-stenting is not to be avoided, especially in high-risk patients, and SFr status needs to be the aim. Finally, CT scans should not be generally overused but should be part of a patient's treatment plan. Prospective studies are required to define SFr status, the size of significant residual fragments, and the modalities of intervention and follow-up.

Development and validation of a predictive model for post-percutaneous nephrolithotomy urinary sepsis: a multicenter retrospective study

BACKGROUND

The objective of this retrospective, multicenter study was to analyze the factors associated with the development of urogenital sepsis after percutaneous nephrolithotomy (PCNL) and to establish a nomogram prediction model of urogenital sepsis after PCNL.

METHODS

A total of 2066 postoperative PCNL patients were included from three medical institutions: Zunyi Medical University Hospital, Beijing Jishuitan Hospital Guizhou Hospital, and Fenggang County People's Hospital. Clinical data of 1623 patients from the Department of Urology of Zunyi Medical University Hospital were randomized into a training cohort (Zunyi training cohort, N.=1139) and an internal validation cohort (Zunyi internal validation cohort, N.=484) using computer generated random numbers in a 7:3 ratio. Univariate and multivariate logistic regression analyses were performed on the compliance training cohort to identify risk factors for urogenital sepsis after PCNL and to develop a column line graph prediction model based on these risk factors. Finally, Zunyi internal validation cohort and two external validation cohorts (Guiyang external cohort, N.=306; Fenggang external cohort, N.=137) were used to validate the prognostic accuracy of the nomogram prediction model. R4.2.2 statistical software was used for all statistical data analyses.

RESULTS

Multifactorial logistic regression analysis of the Zuiyi training cohort (N.=1139) identified five independent risk factors associated with urogenital sepsis after PCNL, including urine culture positivity (odds ratio [OR]=5.29, P<0.001), urine nitrite positivity (OR=5.97, P<0.001), operation time ≥60 min (OR=4.4, P=0.0037), residual stone (OR=5.18, P<0.001), and size ≥30 mm (OR=3.22, P=0.0086). Nomogram were constructed based on these independent risk factors. The area under the curve (AUC) of the nomogram model was 0.907 in the in-progress sample and 0.948 after internal validation. The AUC of the model was 0.855 and 0.804 after external validation of the Guiyang external validation cohort and the Fenggang validation cohort, respectively, indicating good discrimination ability. The calibration curves of the nomogram showed good agreement, and the decision curve analysis demonstrated high clinical utility.

CONCLUSIONS

Based on the clinical independent risk factors such as positive urine culture, positive urine nitrite, operation time ≥60min, stone residue, stone size ≥30mm, nomogram prediction model of urogenital sepsis after PCNL was established, which can provide reference for urologists to develop preoperative evaluation and treatment strategies for patients with percutaneous nephrolithotomy.

Risk Factors of Kidney Stones in Khyber Pakhtunkhwa, Pakistan: A Descriptive Cross-Sectional Study

Introduction Renal calculi, commonly known as kidney stones, affect approximately 12% of the global population, often resulting in mild to severe pain and complications such as infection and renal failure. The causes are multifactorial, involving lifestyle factors, genetic predisposition, and various medical conditions. Despite advancements in treatment, the incidence of kidney stones is on the rise, especially in regions like Asia's stone belt, which includes Pakistan as well. This study investigates the risk factors associated with kidney stones in patients at the Hayatabad Medical Complex, Peshawar, Pakistan, with the goal of informing healthcare policymakers and educating patients to reduce the prevalence and economic burden of the disease in the region. Methods Over a four-month period, 173 patients admitted to the department with confirmed urolithiasis were recruited using a consensus sampling technique. Inclusion criteria were adults aged 18 or older residing in Khyber Pakhtunkhwa, Pakistan. Exclusion criteria included pregnancy, incomplete medical records, secondary causes of renal stones, and unwillingness to participate. Data on socio-demographic factors, clinical history, and lifestyle habits were collected through structured interviews. Descriptive analysis was performed using SPSS software version 23 (IBM Inc, Armonk, New York). Results The study findings indicate that kidney stones were notably prevalent among patients aged 31 to 45 years, with 85 cases identified, comprising 49.1% of the study participants. Furthermore, a significant proportion of affected individuals were males, accounting for 94 cases (54.3%). Those with primary schooling or lower education comprised 106 cases (61.3%), and 124 individuals (71.7%) had lower socioeconomic status. Overweight individuals constituted 81 cases (45.8%) of the total. The study also found a considerable prevalence among residents of rural areas, with 128 cases identified (74.0%). Additionally, 104 cases (60.1%) had a personal history of renal stones. Insufficient water intake was prevalent among 122 individuals (70.5%), while daily consumers of more than one cup of tea also exhibited a higher prevalence, with 97 cases identified (56.1%). Lastly, individuals with a high sodium diet were notably affected, with 112 cases (64.7%) recorded. Conclusion In summary, individuals aged 31-45, males, those residing in rural areas, with lower educational and socioeconomic status, insufficient water intake, a diet high in sodium, personal history of kidney stones, and overweight are at higher risk of urolithiasis. Public education on preventive measures is essential to decrease the incidence of kidney stones and enhance quality of life.

Oxalates: Dietary Oxalates and Kidney Inflammation: A Literature Review

This literature review explores the role of dietary oxalate in the development of chronic inflammatory kidney disease in middle-aged and older individuals. The authors pose the following questions: Is oxalate produced endogenously? If food sources contribute to chronic kidney disease and inflammation, what are those foods? What role do cultural food preparation and cooking play in denaturing food oxalates? The concentration of oxalates found within the body at any particular time is not limited to edible plants; normal human metabolic processes of breaking down ascorbic acid may create up to 30 mg of oxalate daily. Research supports urolithiasis as a common urologic disease in industrialized societies. Approximately 80% of kidney stones are composed of calcium oxalate, resulting in hyperoxaluria. Exogenous (originating outside the cell or organism) oxalate sources include ascorbic acid, amino acids, and glyoxal metabolism. Additional research estimates the daily endogenous (produced within the cell or organism) production of oxalate to be 10-25 mg. Suboptimal colonization of oxalate-degrading bacteria and malabsorptive disease are also contributing factors to the development of chronic kidney disease. Oxalate transcellular processes, though poorly understood, rely on multifunctional anion exchangers, and are currently being investigated. A review of research showed that normal human metabolic processes, including the breakdown of ascorbic acid, account for 35-55% of circulating oxalates and can create ≤30 mg of circulating serum oxalate daily. Glyoxylic acid accounts for 50-70% of circulating urinary oxalate in compromised individuals with liver glycation, bacterial insufficiencies, malabsorption, and anion exchange challenges. For persons with a family history of kidney stones, consumption of foods high in oxalates may be consumed in moderation, provided there is adequate calcium intake in the diet to decrease the absorption of oxalates from the meal ingested.

Is a Vitamin K Epoxide Reductase Complex Subunit 1 (VKORC1) Polymorphism a Risk Factor for Nephrolithiasis in Sarcoidosis?

Sarcoidosis is a systemic inflammatory disorder characterized by granuloma formation in various organs. It has been associated with nephrolithiasis. The vitamin K epoxide reductase complex subunit 1 (VKORC1) gene, which plays a crucial role in vitamin K metabolism, has been implicated in the activation of proteins associated with calcification, including in the forming of nephrolithiasis. This study aimed to investigate the VKORC1 C1173T polymorphism (rs9934438) in a Dutch sarcoidosis cohort, comparing individuals with and without a history of nephrolithiasis. Retrospectively, 424 patients with sarcoidosis were divided into three groups: those with a history of nephrolithiasis (Group I: n = 23), those with hypercalcemia without nephrolithiasis (Group II: n = 38), and those without nephrolithiasis or hypercalcemia (Group III: n = 363). Of the 424 sarcoidosis patients studied, 5.4% had a history of nephrolithiasis (Group I), only two of whom possessed no VKORC1 polymorphisms (OR = 7.73; 95% CI 1.79-33.4; p = 0.001). The presence of a VKORC1 C1173T variant allele was found to be a substantial risk factor for the development of nephrolithiasis in sarcoidosis patients. This study provides novel insights into the genetic basis of nephrolithiasis in sarcoidosis patients, identifying VKORC1 C1173T as a potential contributor. Further research is warranted to elucidate the precise mechanisms and explore potential therapeutic interventions based on these genetic findings.

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.

Comparative analysis of renal calculi treatment via different extracorporeal shock wave lithotripsy (ESWL) pathways

OBJECTIVE

To compare the efficacy and safety of Extracorporeal Shock Wave Lithotripsy (ESWL) for treating renal calculi under different shock wave pathways.

METHODS

This study involved a prospective analysis of clinical data obtained from 264 eligible patients with renal stones treated at the Urology Department of Shanxi Bethune Hospital between January 2021 and June 2023. Among these patients, 125 underwent ESWL via the dorsal shock wave pathway (Group A), while 139 patients underwent ESWL via the ipsilateral clavicular midline shock wave pathway (Group B). Preoperatively, all patients underwent non-contrast abdominal CT (NCCT) scans to assess stone count, diameter, CT values, and Skin-to-Stone Distance (SSD). Intraoperatively, ultrasonography was utilized to remeasure SSD and monitor stone fragmentation continuously. The ESWL procedure employed a standardized intermittent stepwise energy escalation technique until treatment completion. Various metrics, including intraoperative Visual Analog Scale (VAS) pain scores, number of shocks, total shock wave energy, stone-free rate (SFR) at 4 weeks post-operation, and postoperative complication rates, were recorded and subjected to statistical analysis.

RESULTS

There were no statistically significant differences between the two groups regarding gender, age, BMI, stone count, stone diameter, stone CT values, intraoperative VAS pain scores, and postoperative complication rates (P>0.05). Preoperative SSD was significantly higher in Group B than in Group A (P<0.05), but there were no significant differences in intraoperative SSD between the groups (P>0.05). Group B showed significantly lower total shock wave energy and number of shocks compared to Group A (P<0.05). The stone-free rate (SFR) after 4 weeks did not exhibit significant differences between the groups (P>0.05). However, when the stone diameter was ≥1.3 cm, the SFR at 4 weeks post-operation in Group B was significantly higher than in Group A (P<0.05).

CONCLUSION

ESWL emerges as a safe and efficacious approach for treating renal calculi. Our findings suggest that utilizing the ipsilateral clavicular midline shock wave pathway in ESWL necessitates less shock wave energy and enhances efficiency, particularly in cases with larger stone burdens.

Cymbopogon proximus and Petroselinum crispum seed ethanolic extract/Gum Arabic nanogel emulsion: Preventing ethylene glycol and ammonium chloride-induced urolithiasis in rats

Urolithiasis is a prevalent urological disorder that contributes significantly to global morbidity. This study aimed to assess the anti-urolithic effects of Cymbopogon proximus (Halfa Bar) and Petroselinum crispum (parsley) seed ethanolic extract /Gum Arabic (GA) emulsion, and its nanogel form against ethylene glycol (EG) and ammonium chloride (AC)-induced experimental urolithiasis in rats. Rats were divided into four groups: group 1 served as the normal control, group 2 received EG with AC in drinking water for 14 days to induce urolithiasis, groups 3 and 4 were orally administered emulsion (600 mg/kg/day) and nanogel emulsion (600 mg/kg/day) for 7 days, followed by co-administration with EG and AC in drinking water for 14 days. Urolithiatic rats exhibited a significant decrease in urinary excreted magnesium, and non-enzymic antioxidant glutathione and catalase activity. Moreover, they showed an increase in oxalate crystal numbers and various urolithiasis promoters, including excreted calcium, oxalate, phosphate, and uric acid. Renal function parameters and lipid peroxidation were intensified. Treatment with either emulsion or nanogel emulsion significantly elevated urolithiasis inhibitors, excreted magnesium, glutathione levels, and catalase activities. Reduced oxalate crystal numbers, urolithiasis promoters' excretion, renal function parameters, and lipid peroxidation while improving histopathological changes. Moreover, it decreased renal crystal deposition score and the expression of Tumer necrosis factor-α (TNF-α) and cleaved caspase-3. Notably, nanogel emulsion showed superior effects compared to the emulsion. Cymbopogon proximus (C. proximus) and Petroselinum crispum (P. crispum) seed ethanolic extracts/GA nanogel emulsion demonstrated protective effects against ethylene glycol induced renal stones by mitigating kidney dysfunction, oxalate crystal formation, and histological alterations.

High Self-Reported Prevalence of Kidney Stones in Trinidad and Tobago: Results of a Cross-Sectional Online Survey

Introduction No data exist on the prevalence of kidney stone disease in Trinidad and Tobago. Local clinicians have noted that the disease is very common, and this study represents the first attempt to investigate the prevalence of urolithiasis in these islands. Objectives The objective is to estimate the prevalence of kidney stone disease in Trinidad and Tobago and to investigate the epidemiology of the disease. Methods An online survey using the online tool Survey Monkey was distributed among members of the public via instant messaging and social media. The survey captured data relating to the stone status and demographics of respondents. Results 1225 patients completed the survey of whom 46.5% were males and 53.5% were females. Respondents were equally distributed throughout the country. 16.74% of those surveyed indicated that they were currently affected by stones confirmed by imaging. Kidney stones were more common among Trinidadians of East Indian ancestry (20.6% vs 10.6%). Positive correlations were established between kidney stones and the presence of hypertension, diabetes, and gout. Persons with kidney stones were more likely to have a family member with the disease - 45.6% vs 31.4% among those without kidney stones. Conclusion This study demonstrates a high self-reported prevalence of kidney stones in Trinidad and Tobago.

Correlation research demonstrates that an inflammatory diet is a risk factor for calcium oxalate renal stone formation

BACKGROUND AND AIMS

Previous studies have demonstrated associations between the Dietary Inflammatory Index (DII®), an analytical tool which evaluates the inflammatory potential of the diet according to the pro- and anti-inflammatory properties of its components, and renal stone formation. However, these have not comprehensively addressed important parameters such as stone type, gender, DII scores in stone formers (SFs) and healthy controls (Cs) and associations of DII with urine and blood chemistries. These were adopted as the survey parameters for the present study, the purpose of which was to test whether the contributory role of an inflammatory diet on stone formation could be further confirmed.

METHODS

97 calcium oxalate (CaOx) SFs and 63 Cs, matched for age and gender each completed a semi-quantitative food frequency questionnaire from which nutrient composition was computed. These data were used to calculate the DII® score. To control the effect of energy intake, energy-adjusted DII scores were calculated per 1000 kcal consumed (E-DII™). A single blood sample and two consecutive overnight (8h) urine samples were collected from a subset (n = 59 SFs and n = 54 Cs) of the overall number of particpants (n = 160). These were analysed for renal stone risk factors. Data were analysed using regression models fit in R software.

RESULTS

E-DII scores were found to fit the data better than DII, so they were used throughout. E-DII scores were significantly more positive (more pro-inflammatory) in SFs than in controls in the combined gender group (-0.34 vs. -1.73, p < 0.0001) and separately in males (-0.43 vs. -1.78, p = 0.01) and females (-0.26 vs. - 1.61, p = 0.05). In blood, a significant negative correlation was seen between E-DII and HDL cholesterol. In urine significant positive correlations were seen between E-DII and each of calcium (ρ = 0.25, p = 0.02), phosphate (ρ = 0.48, p < 0.001), magnesium (ρ = 0.33, p < 0.0001) and uric acid (ρ = 0.27, p = 0.004) concentrations. A significant negative correlation was seen between E-DII and urinary volume ρ = -0.27, p = 0.003). There was no correlation between E-DII scores and the relative supersaturations of urinary CaOx, calcium phosphate (brushite) and uric acid.

CONCLUSIONS

Our findings provide hitherto unreported quantitative evidence in support of the notion that the diet of calcium oxalate renal stone patients is significantly more pro-inflammatory than that of healthy controls.

Automatic Urinary Stone Detection System for Abdominal Non-Enhanced CT Images Reduces the Burden on Radiologists

To develop a fully automatic urinary stone detection system (kidney, ureter, and bladder) and to test it in a real clinical environment. The local institutional review board approved this retrospective single-center study that used non-enhanced abdominopelvic CT scans from patients admitted urology (uPatients) and emergency (ePatients). The uPatients were randomly divided into training and validation sets in a ratio of 3:1. We designed a cascade urinary stone map location-feature pyramid networks (USm-FPNs) and innovatively proposed a ureter distance heatmap method to estimate the ureter position on non-enhanced CT to further reduce the false positives. The performances of the system were compared using the free-response receiver operating characteristic curve and the precision-recall curve. This study included 811 uPatients and 356 ePatients. At stone level, the cascade detector USm-FPNs has the mean of false positives per scan (mFP) 1.88 with the sensitivity 0.977 in validation set, and mFP was further reduced to 1.18 with the sensitivity 0.977 after combining the ureter distance heatmap. At patient level, the sensitivity and precision were as high as 0.995 and 0.990 in validation set, respectively. In a real clinical set of ePatients (27.5% of patients contain stones), the mFP was 1.31 with as high as sensitivity 0.977, and the diagnostic time reduced by > 20% with the system help. A fully automatic detection system for entire urinary stones on non-enhanced CT scans was proposed and reduces obviously the burden on junior radiologists without compromising sensitivity in real emergency data.

Clinical characteristics of adult cases with urolithiasis from Turkey: A regional epidemiological study

OBJECTIVE

To evaluate the metabolic and clinical characteristics of adult cases with stone disease from a regional part of Turkey.

METHODS

The study included 2348 adult patients with sonography and/or computed tomography-proven urinary stones. All cases were given a questionnaire about the epidemiological features of urolithiasis. Aside from the type and severity of stoneforming risk factors, both patient (age, gender, BMI, associated comorbidities, first onset of stone disease, positive family history, educational level) and stone-related (size, number, location, chemical composition, previous stone attacks) factors have been thoroughly assessed. The data were evaluated in multiple aspects to outline the epidemiological features.

RESULTS

The overall mean age value of the cases was 43.3 years, and the M/F ratio was 1.34. The first onset of the disease was found to vary between 15-57 years, with a mean value of 32.4 years. While most of the stones were located in kidney and ureter, calcium-containing stones constituted the most common type (CaOx 69%, CaOxPO4 7%). More than 42% of the cases suffered from multiple stone attacks; positive family history was present in 31.6%. Among the associated comorbidities, hypertension was the most common pathology (45.8%), and the BMI index value was >30 in 31.3% of the cases. 57.7% of the patients had just one stone attack, and 42.2% had recurrent stone formation.

CONCLUSIONS

Our findings clearly show that important implications may be extracted from epidemiologic data acquired from local scale research to implement an effective preventative program and closely monitor the patients.

Sodium-Glucose Cotransporter 2 Inhibitors and Nephrolithiasis Risk in Patients With Type 2 Diabetes

Importance

Type 2 diabetes (T2D) is associated with an increased risk of kidney stones. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) might lower the risk of nephrolithiasis by altering urine composition. However, no studies have investigated the association between SGLT2i use and nephrolithiasis risk in patients receiving routine care in the US.

Objective

To investigate the association between SGLT2i use and nephrolithiasis risk in clinical practice.

Design, Setting, and Participants

This new-user, active comparator cohort study used data from commercially insured adults (aged ≥18 years) with T2D who initiated treatment with SGLT2is, glucagon-like peptide 1 receptor agonists (GLP-1RAs), or dipeptidyl peptidase 4 inhibitors (DPP4is) between April 1, 2013, and December 31, 2020. The data were analyzed from July 2021 through June 2023.

Exposure

New initiation of an SGLT2i, GLP-1RA, or DPP4i.

Main Outcomes and Measures

The primary outcome was nephrolithiasis diagnosed by International Classification of Diseases codes in the inpatient or outpatient setting. New SGLT2i users were 1:1 propensity score matched to new users of a GLP-1RA or DPP4i in pairwise comparisons. Incidence rates, rate differences (RDs), and estimated hazard ratios (HRs) with 95% CIs were calculated.

Results

After 1:1 propensity score matching, a total of 716 406 adults with T2D (358 203 pairs) initiating an SGLT2i or a GLP-1RA (mean [SD] age, 61.4 [9.7] years for both groups; 51.4% vs 51.2% female; 48.6% vs 48.5% male) and 662 056 adults (331 028 pairs) initiating an SGLT2i or a DPP4i (mean [SD] age, 61.8 [9.3] vs 61.7 [10.1] years; 47.4% vs 47.3% female; 52.6% vs 52.7% male) were included. Over a median follow-up of 192 (IQR, 88-409) days, the risk of nephrolithiasis was lower in patients initiating an SGLT2i than among those initiating a GLP-1RA (14.9 vs 21.3 events per 1000 person-years; HR, 0.69 [95% CI, 0.67-0.72]; RD, -6.4 [95% CI, -7.1 to -5.7]) or a DPP4i (14.6 vs 19.9 events per 1000 person-years; HR, 0.74 [95% CI, 0.71-0.77]; RD, -5.3 [95% CI, -6.0 to -4.6]). The association between SGLT2i use and nephrolithiasis risk was similar by sex, race and ethnicity, history of chronic kidney disease, and obesity. The magnitude of the risk reduction with SGLT2i use was larger among adults aged younger than 70 years vs aged 70 years or older (HR, 0.85 [95% CI, 0.79-0.91]; RD, -3.46 [95% CI, -4.87 to -2.05] per 1000 person-years; P for interaction <.001).

Conclusions and Relevance

These findings suggest that in adults with T2D, SGLT2i use may lower the risk of nephrolithiasis compared with GLP-1RAs or DPP4is and could help to inform decision-making when prescribing glucose-lowering agents for patients who may be at risk for developing nephrolithiasis.

Seminal papers in urology: urinary volume, water and recurrences in idiopathic calcium nephrolithiasis: a 5-year randomized prospective study : Borghi L, Meschi T, Amato F, Briganti A, Novarini A, Giannini A. urinary volume, water and recurrences in idiopathic calcium nephrolithiasis: a 5-year randomized prospective study. The Journal of urology. 1996 Mar;155(3):839 - 43

Kidney stones, a persistent urological condition, continue to affect people globally. In this critical review, we examine the work of Borghi et al. who evaluated patients with idiopathic stone formation and randomised 99 patients to increased water intake (≥ 2 L/day) and 100 patients to usual care in a 5-year randomized controlled trial. The study examined baseline urine volume in individuals with idiopathic calcium stones, recurrence rates, and relevant biochemical factors. The study found reduced recurrence rate (12.1% vs. 27% (p = 0.008)), and time to recurrence with increased water intake (38.7 ± 13.2 months) vs. (25 ± 16.4 months) (p = 0.016). These findings inform clinical practice, contributing to the guideline recommendations that kidney stone patients should aim for fluid intake of at least 2.5 L per day to prevent stone recurrence.

Ultrasound accuracy in evaluating renal calculi in Maysan province

Renal calculi are a common clinical presentation. While ultrasound (US) is a widely used imaging modality for kidney stone diagnosis due to its accessibility and lower cost, its accuracy compared to computerized tomography (CT), the gold standard, remains understudied. This cross-sectional study evaluated the diagnostic accuracy of ultrasound for detecting and characterizing kidney stones compared to computed tomography (CT). Fifty-six patients with suspected kidney stones based on flank pain underwent abdominal ultrasound to assess stone presence, size, location, and the severity of any hydronephrosis (kidney swelling). These findings were then confirmed with a subsequent non-contrast CT scan. There was a fair agreement between US and CT (Kappa = 0.368) for detecting the stone location. The US could not detect 7 (12.5%) stones, being less sensitive in the middle and upper calyx compared to CT. There was a fair agreement between the US and CT (Kappa = 0.394) for detecting the severity of hydronephrosis. The US was less sensitive to moderate and severe hydronephrosis compared to CT. The abdominal ultrasound demonstrated excellent reliability for stone size measurement (intraclass correlation = 0.924), with CT measurements only slightly larger on average (mean difference 0.9 mm). Although abdominal ultrasound provides reliable stone size assessment, its capacity to accurately localize stones and assess hydronephrosis severity is limited.

Left endoscopic combined intrarenal surgery with electrocoagulation hemostasis and right flexible ureteroscopic lithotripsy for bilateral upper urinary tract stones: a case report

Background

Percutaneous nephrolithotomy (PCNL) is the first-line treatment for large renal stones. However, multi-tract or staged procedures may be necessitated in bilateral or anatomically-complex stones to achieve stone clearance. Endoscopic combined intrarenal surgery (ECIRS) integrates the advantages of PCNL and retrograde intrarenal surgery. In this article, we detail a hybrid surgical technique adopted for the management of complex simultaneous bilateral upper urinary tract stones. In addition, we discuss the advantages and disadvantages of combining a variety of new techniques that may improve post-operative outcomes and patient satisfaction.

Case Description

We report the case of a 36-year-old male with a large left renal pelvis stone, right proximal ureteric stone, and bilateral renal stones. Biochemical results showed raised inflammatory markers but he denied pre-stenting and staged surgery. After receiving 3-day antibiotic prophylaxis, he underwent an elective hybrid procedure. Under split-leg prone position, we performed a hybrid procedure that included left ECIRS with tubeless single-tract mini PCNL and left flexible ureteroscopy, and right flexible ureteroscopic lithotripsy. Hemostasis was achieved by electrocauterization with a novel device. The patient made an uneventful recovery. Follow-up computed tomography (CT) at 1-month revealed complete stone clearance.

Conclusions

Unilateral ECIRS with tubeless single-tract mini PCNL with electrocoagulation hemostasis and adjacent retrograde intrarenal surgery in split-leg prone position is a safe, feasible, and efficient technique to manage large renal stones.

Hydration for Adult Patients with Nephrolithiasis: Specificities and Current Recommendations

Nephrolithiasis affects around 10% of the population and is frequently associated with impaired dietary factors. The first one is insufficient fluid intake inducing reduced urine volume, urine supersaturation, and subsequently urinary lithiasis. Kidneys regulate 24 h urine volume, which, under physiological conditions, approximately reflects daily fluid intake. The aim of this study is to synthesize and highlight the role of hydration in the treatment of nephrolithiasis. Increasing fluid intake has a preventive effect on the risk of developing a first kidney stone (primary prevention) and also decreases the risk of stone recurrence (secondary prevention). Current guidelines recommend increasing fluid intake to at least at 2.5 L/day to prevent stone formation, and even to 3.5-4 L in some severe forms of nephrolithiasis (primary or enteric hyperoxaluria or cystinuria). Fluid intake must also be balanced between day and night, to avoid urinary supersaturation during the night. Patients should be informed and supported in this difficult process of increasing urine dilution, with practical ways and daily routines to increase their fluid intake. The liquid of choice is water, which should be chosen depending on its composition (such as calcium, bicarbonate, or magnesium content). Finally, some additional advice has to be given to avoid certain beverages such as those containing fructose or phosphoric acid, which are susceptible to increase the risk of nephrolithiasis.

Epidemiology and composition of upper urinary tract lithiasis in Senegalese population: a multicenter retrospective study

Urolithiasis is a major public health issue due to its increasing prevalence. The objective of this study was to describe the spectrophotometric profile of upper urinary tract stones (UTS) in Senegal. We conducted a multicenter retrospective study of all patients treated for upper UTS whose chemical composition was analyzed from January 2014 to January 2020 in eight regions of Senegal. Socio-demographic, clinical, paraclinical, and prognosis data were collected and analyzed. Three hundred and thirty-four patients were included in this study with a mean age of 46.3 ± 18.4 years and a sex ratio of 1.38. About one-third of patients (31.1%) had a body mass index > 25 kg/m2 and 74.2% presented with lumbar pain was the main clinical symptom. Calcium oxalate and calcium phosphate stones were the predominant types found, respectively, in 37.7% and 24.5% of patients. Uric acid was the main stone constituent in 18.6% of patients and struvites represented 14.7% of cases. Stones were located in the renal calyces and pelvis in 71.2% of cases. Surgical lithotomy was performed in 62.7% of patients for UTS extraction. Upper UTS are frequent condition in Senegalese with predominance of males and young adults. Calcium and uric acid stones are the main types. Preventive dietary and lifestyle measures are needed to reduce their burden.

Role of Climate Change in Urologic Health: Kidney Stone Disease

Kidney stones are rising in incidence and prevalence worldwide. Given the temperature dependence of kidney stone presentations, climate change is projected to further increase the burden of disease for individuals and society. PATIENT SUMMARY: This mini-review reports current knowledge on climate change in relation to kidney stone disease. Kidney stones are more common in patients living in parts of the world that are hotter and more humid. Kidney stone problems are also more common after periods of high heat, which have a greater impact on men than on women. As temperatures rise with climate change, it is likely that the occurrence of kidney stones and the costs associated with their diagnosis and treatment will increase as well.

Clinical Reproducibility of the Stone Volume Measurement: A "Kidney Stone Calculator" Study

BACKGROUND

An accurate estimation of the stone burden is the key factor for predicting retrograde intra-renal surgical outcomes. Volumetric calculations better stratify stone burden than linear measurements. We developed a free software to assess the stone volume and estimate the lithotrity duration according to 3D-segmented stone volumes, namely the Kidney Stone Calculator (KSC). The present study aimed to validate the KSC's reproducibility in clinical cases evaluating its inter-observer and intra-observer correlations.

METHODS

Fifty patients that harbored renal stones were retrospectively selected from a prospective cohort. For each patient, three urologists with different experience levels in stone management made five measurements of the stone volume on non-contrast-enhanced computed tomography (NCCT) images using the KSC.

RESULTS

the overall inter-observer correlation (Kendall's concordance coefficient) was 0.99 (p < 0.0001). All three paired analyses of the inter-observer reproducibility were superior to 0.8. The intra-observer variation coefficients varied from 4% to 6%, and Kendall's intra-observer concordance coefficient was found to be superior to 0.98 (p < 0.0001) for each participant. Subgroup analyses showed that the segmentation of complex stones seems to be less reproductible.

CONCLUSIONS

The Kidney Stone Calculator is a reliable tool for the stone burden estimation. Its extension for calculating the lithotrity duration is of major interest and could help the practitioner in surgical planning.

Metabolomic profiles and pathogenesis of nephrolithiasis

PURPOSE OF REVIEW

Kidney stone disease is caused by supersaturation of urine with certain metabolites and minerals. The urine composition of stone formers has been measured to prevent stone recurrence, specifically calcium, uric acid, oxalate, ammonia, citrate. However, these minerals and metabolites have proven to be unreliable in predicting stone recurrence. Metabolomics using high throughput technologies in well defined patient cohorts can identify metabolites that may provide insight into the pathogenesis of stones as well as offer possibilities in therapeutics.

RECENT FINDINGS

Techniques including 1H-NMR, and liquid chromatography paired with tandem mass spectroscopy have identified multiple possible metabolites involved in stone formation. Compared to formers of calcium oxalate stones, healthy controls had higher levels of hippuric acid as well as metabolites involved in caffeine metabolism. Both the gut and urine microbiome may contribute to the altered metabolome of stone formers.

SUMMARY

Although metabolomics has offered several potential metabolites that may be protective against or promote stone formation, the mechanisms behind these metabolomic profiles and their clinical significance requires further investigation.

Oxalate (dys)Metabolism: Person-to-Person Variability, Kidney and Cardiometabolic Toxicity

Oxalate is a metabolic end-product whose systemic concentrations are highly variable among individuals. Genetic (primary hyperoxaluria) and non-genetic (e.g., diet, microbiota, renal and metabolic disease) reasons underlie elevated plasma concentrations and tissue accumulation of oxalate, which is toxic to the body. A classic example is the triad of primary hyperoxaluria, nephrolithiasis, and kidney injury. Lessons learned from this example suggest further investigation of other putative factors associated with oxalate dysmetabolism, namely the identification of precursors (glyoxylate, aromatic amino acids, glyoxal and vitamin C), the regulation of the endogenous pathways that produce oxalate, or the microbiota's contribution to oxalate systemic availability. The association between secondary nephrolithiasis and cardiovascular and metabolic diseases (hypertension, type 2 diabetes, and obesity) inspired the authors to perform this comprehensive review about oxalate dysmetabolism and its relation to cardiometabolic toxicity. This perspective may offer something substantial that helps advance understanding of effective management and draws attention to the novel class of treatments available in clinical practice.

An Evaluation of Parylene Thin Films to Prevent Encrustation for a Urinary Bladder Pressure MEMS Sensor System

Recent developments in urological implants have focused on preventive strategies to mitigate encrustation and biofilm formation. Parylene, a conformal, pinhole-free polymer coating, has gained attention due to its high biocompatibility and chemical resistance, excellent barrier properties, and low friction coefficient. This study aims to evaluate the effectiveness of parylene C in comparison to a parylene VT4 grade coating in preventing encrustation on a urinary bladder pressure MEMS sensor system. Additionally, silicon oxide (SiOx) applied as a finish coating was investigated for further improvements. An in vitro encrustation system mimicking natural urine flow was used to quantify the formation of urinary stones. These stones were subsequently analyzed using Fourier transform infrared spectrometry (FTIR). Encrustation results were then discussed in relation to coating surface chemical properties. Parylene C and VT4 grades demonstrated a very low encrustation mass, making them attractive options for encrustation prevention. The best performance was achieved after the addition of a hydrophilic SiOx finish coating on parylene VT4 grade. Parylene-based encapsulation proved to be an outstanding solution to prevent encrustation for urological implants.

Chemical Studies of Multicomponent Kidney Stones Using the Modern Advanced Research Methods

Defining the kidney stone composition is important for determining a treatment plan, understanding etiology and preventing recurrence of nephrolithiasis, which is considered as a common, civilization disease and a serious worldwide medical problem. The aim of this study was to investigate the morphology and chemical composition of multicomponent kidney stones. The identification methods such as infrared spectroscopy (FTIR), X-ray diffraction (XRD), and electron microscopy with the EDX detector were presented. The studies by the X-ray photoelectron spectroscopy (XPS) were also carried out for better understanding of their chemical structure. The chemical mapping by the FTIR microscopy was performed to show the distribution of individual chemical compounds that constitute the building blocks of kidney stones. The use of modern research methods with a particular emphasis on the spectroscopic methods allowed for a thorough examination of the subject of nephrolithiasis.

Associations between smoke exposure and kidney stones: results from the NHANES (2007-2018) and Mendelian randomization analysis

Purpose

It is currently controversial whether smoke exposure is associated with the risk of kidney stones. Herein, publicly available databases were combined to explore relationships with the risk of nephrolithiasis in terms of smoking status and serum cotinine concentrations.

Materials and methods

First, we conducted an observational study using data from 2007 to 2018, based on the National Health and Nutrition Examination Survey (NHANES) database. Univariate analysis, multivariate logistic regression, trend testing, restricted cubic spline (RCS), and multiple imputation (MI) were the main analytical methods of our study. Then, A Mendelian randomization (MR) analysis was performed to explore the causal relationship between serum cotinine and nephrolithiasis. Genetic instruments for serum cotinine and pooled data for kidney stones were derived from publicly available large-scale genome-wide association studies (GWAS). Inverse-variance weighting (IVW) was the primary method for our MR analysis.

Results

A total of 34,657 and 31,352 participants were included in the observational study based on smoking status and serum cotinine concentrations, respectively. Under full adjustment of covariates, current smokers had an increased risk of kidney stones compared to non-smokers [OR = 1.17 (1.04-1.31), P = 0.009, P for trend = 0.010]. Compared with serum cotinine of <0.05 ng/ml, serum cotinine levels of 0.05-2.99 ng/ml [OR = 1.15 (1.03-1.29), P = 0.013] and ≥3.00 ng/ml [OR = 1.22 (1.10-1.37), P < 0.001] were observed to have a higher risk of nephrolithiasis (P for trend < 0.001). In addition, a non-linear relationship between log2-transformed serum cotinine and the risk of nephrolithiasis was found (P for non-linearity = 0.028). Similar results were found when serum cotinine (log2 transformation) was used as a continuous variable [OR = 1.02 (1.01-1.03), P < 0.001] or complete data was used to analyze after MI. In the MR analysis, genetically predicted high serum cotinine was causally related to the high risk of nephrolithiasis [IVW: OR = 1.09 (1.00-1.19), P = 0.044].

Conclusion

Current smoking and high serum cotinine concentrations may be associated with an increased risk of kidney stones. Further research is needed to validate this relationship and explore its underlying mechanisms.

A Mechanistic Insight into Beneficial Effects of Polyphenols in the Prevention and Treatment of Nephrolithiasis: Evidence from Recent In Vitro Studies

Nephrolithiasis is a pathological condition characterized by the formation of solid crystals in the kidneys or other parts of urinary tract. Kidney stones are a serious public health issue and financial burden for health care system, as well as a painful and uncomfortable condition for patients, resulting in renal tissue injury in severe cases. Dietary habits, low fluid and high salt intake predominantly, contribute to the development of kidney stones. Current research suggests that polyphenols have a protective effect in the pathogenesis of kidney stones. Polyphenols are a group of naturally occurring compounds found in plant-based foods such as fruits, vegetables, tea, and coffee. In this review, we explore mechanisms underlying the beneficial effects of polyphenols, such as oxidative stress reduction and modulation of inflammatory pathways, in various in vitro models of nephrolithiasis. Additionally, certain polyphenols, such as catechins found in green tea, have been shown to inhibit the formation and growth of kidney stones in animal studies. This review highlights the antioxidant and anti-inflammatory effects, as well as the inhibition of crystal formation, as results of polyphenol treatment in vitro. Further research is required to determine the specific effects of polyphenols on kidney stone formation in humans; however, current knowledge implicates that incorporating a variety of polyphenol-rich foods into the diet may be a beneficial strategy for individuals at risk of developing nephrolithiasis.

Development of convenient crystallization inhibition assays for structure-activity relationship studies in the discovery of crystallization inhibitors

Kidney stone diseases are increasing globally in prevalence and recurrence rates, indicating an urgent medical need for developing new therapies that can prevent stone formation. One approach we have been working on is to develop small molecule inhibitors that can interfere with the crystallization process of the chemical substances that form the stones. For these drug discovery efforts, it is critical to have available easily accessible assay methods to evaluate the potential inhibitors and rank them for structure-activity relationship studies. Herein, we report a convenient, medium-to-high throughput assay platform using, as an example, the screening and evaluation of inhibitors of L-cystine crystallization for the prevention of kidney stones in cystinuria. The assay involves preparing a supersaturated solution, followed by incubating small volumes (<1 mL) of the supersaturated solution with test inhibitors for 72 hours, and finally measuring L-cystine concentrations in the supernatants after centrifugation using either a colorimetric or fluorometric method. Compared to traditional techniques for studying crystallization inhibitors, this miniaturized multi-well assay format is simple to implement, cost-effective, and widely applicable in determining and distinguishing the activities of compounds that inhibit crystallization. This assay has been successfully employed to discover L-cystine diamides as highly potent inhibitors of L-cystine crystallization such as LH708 with an EC50 of 0.058 μM, 70-fold more potent than L-CDME (EC50 = 4.31 μM).

Efficacy of Theobromine and Its Metabolites in Reducing the Risk of Uric Acid Lithiasis

Uric acid lithiasis accounts for about 10% of all types of renal lithiasis. The most common causes of uric acid lithiasis are low urinary pH, followed by high concentration of urinary uric acid, and low diuresis. Treatment of patients consists of alkalinization of urine, reducing the consumption of purine-rich foods, and administration of xanthine oxidase inhibitors, because there are no established therapeutic inhibitors of uric acid crystallization. We recently found that theobromine inhibited uric acid crystallization in vitro, and that the increased urinary level of theobromine following its oral consumption was associated with the prevention of uric acid crystallization. In this study, we evaluated the inhibitory effects of theobromine metabolites and other methylxanthine-related compounds on uric acid crystallization. We also measured the urinary concentrations of theobromine and its metabolites in samples from healthy individuals and patients with uric acid stones and compared the extent of uric acid supersaturation and uric acid crystal formation in these different samples. Theobromine and other methylxanthines that lacked a substituent at position 1 inhibited uric acid crystallization, but other methylxanthines did not have this effect. Individuals with clinical parameters that favored uric acid crystallization did not develop uric acid crystals when theobromine and its metabolites were in the urine at high levels. Thus, theobromine and its metabolites reduced the risk of uric acid lithiasis.

Analysis of Nephrolithiasis Treatment in Highest Reference Hospital-Occurrence of Acromegaly in the Study Group

BACKGROUND

Urolithiasis is one of the most common diseases of the urinary system, the incidence of which is assumed to be up to 100,000 cases per million (10% of the population). The cause of it is dysregulation of renal urine excretion. Acromegaly is a very rare endocrine disorder that causes a somatotropic pituitary adenoma producing higher amounts of growth hormone. It occurs approximately in 80 cases per million (about 0.008% of the population). One of the acromegaly complications may be urolithiasis.

METHODS

Clinical and laboratory results of 2289 patients hospitalized for nephrolithiasis in the highest reference hospital were retrospectively analyzed, distinguishing a subgroup of patients with acromegaly. Statistical analysis was performed to compare the prevalence of the disease in the analyzed subgroup with the epidemiological results available in up-to-date literature.

RESULTS

The distribution of nephrolithiasis treatment was definitely in favor of non-invasive and minimally invasive treatment. The methods used were as follows: ESWL (61.82%), USRL (30.62%), RIRS (4.15%), PCNL (3.1%), and pyelolithotomy (0.31%). Such a distribution limited the potential complications of the procedures while maintaining the high effectiveness of the treatment. Among two thousand two hundred and eighty-nine patients with urolithiasis, two were diagnosed with acromegaly before the nephrological and urological treatment, and seven were diagnosed de novo. Patients with acromegaly required a higher percentage of open surgeries (including nephrectomy) and also had a higher rate of kidney stones recurrence. The concentration of IGF-1 in patients with newly diagnosed acromegaly was similar to those treated with somatostatin analogs (SSA) due to incomplete transsphenoidal pituitary surgery.

CONCLUSIONS

In the population of patients with urolithiasis requiring hospitalization and interventional treatment compared to the general population, the prevalence of acromegaly was almost 50-fold higher (p = 0.025). Acromegaly itself increases the risk of urolithiasis.