Medical management of kidney stones: AUA guideline

Prospective Evaluation of Extracorporeal Shockwave Lithotripsy in Renal and Upper Ureteric Stone Treatment: Clinical Assessment and Results

INTRODUCTION

Extracorporeal shockwave lithotripsy (ESWL) is a widely accepted non-invasive treatment for renal and upper ureteric stones smaller than 2 cm due to its safety and efficacy. Despite advancements in minimally invasive techniques, extracorporeal shockwave lithotripsy remains an important modality.

AIMS AND OBJECTIVE

This prospective observational study aimed to evaluate the outcomes of ESWL in managing renal and upper ureteric stones measuring less than 2 cm in terms of stone clearance.

MATERIAL AND METHODS

In a study conducted at a university-affiliated tertiary care hospital, 119 patients with renal and upper ureteric stones underwent extracorporeal shockwave lithotripsy over a 12-month period. Data on patient demographics, stone characteristics, treatment procedures, and complications were collected. Follow-up assessments were performed at two-week intervals for up to two months post-treatment.

RESULTS

The mean age of patients was 39.78 years, with a mean stone size of 1.2 cm. Right kidney stones were more prevalent (61.3% [n=76]). Complications included fever (19.3% [n=23]), gross haematuria (24.3% [n=29]), and steinstrasse (21.8% [n=26]). The success rate of extracorporeal shockwave lithotripsy was 81.5% (n=97), with 18.5% (n=22) of patients requiring surgical intervention due to incomplete fragmentation or residual fragments >4 mm. Stone size and density played significant roles in treatment success.

CONCLUSION

Despite advancements in minimally invasive techniques, ESWL retains its significance as a noninvasive and effective treatment option for renal and upper ureteric stones smaller than 2 cm. Its success depends on various factors, including the stone site, size, and composition. ESWL offers advantages such as minimal morbidity, shorter hospital stays, and better patient compliance. Complications such as steinstrasse are manageable with conservative measures or ancillary procedures. While ESWL may be losing ground in some cases, its noninvasive nature and favourable outcomes make it a valuable option in the armamentarium for stone management.

Surgeon, and Institution Characteristics Associated Surgical Preferences in the Pediatric KIDney Stone Care Improvement Network

OBJECTIVE

To reveal barriers and opportunities to implement evidence for the management of pediatric kidney stone disease, we determined surgeon and institutional factors associated with preferences for the type of surgical intervention for kidney and ureteral stones.

METHODS

We conducted a cross-sectional study of urologists participating in the Pediatric KIDney Stone Care Improvement Network (PKIDS) trial. Questionnaires ascertained strengths of urologists' preferences for types of surgery as well as characteristics of participating urologists and institutions. The outcome was the strength of preferences for ureteroscopy, shockwave lithotripsy, and percutaneous nephrolithotomy for four scenarios for which two alternative procedures are recommended by the AUA guidelines: (1) 2 cm kidney stone, (2) 9 mm proximal ureteral stone, (3) 1.5 cm lower pole kidney stone, (4) 1 cm nonlower pole kidney stone. Principal component analysis was performed to identify unique clusters of factors that explain surgical preferences.

RESULTS

One hundred forty-eight urologists at 29 sites completed surveys. Stated preferences were highly skewed except for the choice between ureteroscopy and percutaneous nephrolithotomy for a 1.5 cm kidney stone. Shockwave lithotripsy ownership and local practice patterns most frequently associated with the strength of surgeons' preferences for the type of surgery. Principal component analysis revealed that three clusters of stone, patient, and heterogenous characteristics explained 30% of the variance in preferences.

CONCLUSION

There is wide variation in the strengths of preferences for surgical interventions supported by current guidelines that are partially explained by surgeon and institutional characteristics. These results reveal opportunities to develop strategies for guidelines that consider real-world drivers of care.

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.

Medical management of urolithiasis: Great efforts and limited progress

Objective

To provide a comprehensive review on the existing literature on medical management of urolithiasis.

Methods

A thorough literature review was performed using Medline, PubMed/PMC, Embase, and the Cochrane Database of Systematic Reviews up to December 2022 to identify publications on the medical management of urolithiasis. Studies that assessed dietary and pharmacologic management of urolithiasis were reviewed; studies on medical expulsive therapy were not included in this review.

Results

Medical management of urolithiasis ranges from the prophylactic management of kidney stone disease to dissolution therapies. While most treatment concepts have been long established, large randomized controlled trials are scarce. Dietary modification and increased fluid intake remain cornerstones in the conservative management of urolithiasis. A major limitation for medical management of urolithiasis is poor patient compliance.

Conclusion

Medical management of urolithiasis is more important in patients with recurrent urolithiasis and patients with metabolic abnormalities putting them at higher risk of developing stones. Although medical management can be effective in limiting stone recurrence, medical interventions often fail due to poor compliance.

International Alliance of Urolithiasis (IAU) guideline on staghorn calculi management

BACKGROUND

The stone burden based management strategy reported in the guidelines published by different associations is well known for a long time. Staghorn calculi, representing the largest burden and most complex stones, is one of the most challenging cases to practicing urologists in clinical practice. The International Alliance of Urolithiasis (IAU) has released a series of guidelines on the management of urolithiasis.

PURPOSE

To develop a series of recommendations for the contemporary management management of staghorn calculi and to provide a clinical framework for urologists treating patients with these complex stones.

METHODS

A comprehensive literature search for articles published in English between 01/01/1976 and 31/12/2022 in the PubMed, OVID, Embase and Medline database is performed. A series of recommendations are developed and individually graded following the review of literature and panel discussion.

RESULTS

The definition, pathogenesis, pathophysiology, preoperative evaluation, intraoperative treatment strategies and procedural advice, early postoperative management, follow up and prevention of stone recurrence are summarized in the present document.

CONCLUSION

A series of recommendations regarding the management of staghorn calculi, along with related commentary and supporting documentation offered in the present guideline is intended to provide a clinical framework for the practicing urologists in the management of staghorn calculi.

Pathophysiology and Main Molecular Mechanisms of Urinary Stone Formation and Recurrence

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

Promoting fluid intake to increase urine volume for kidney stone prevention: Protocol for a randomized controlled efficacy trial of the sipIT intervention

BACKGROUND

Risk of kidney stone recurrence can be reduced by increasing fluid intake and urine production but most patients fail to adhere to recommended clinical guidelines. Patients have indicated that common barriers to fluid intake include a lack of thirst, forgetting to drink, and not having access to water. We developed the sipIT intervention to support patients' fluid intake with semi-automated tracking (via a mobile app, connected water bottle and a smartwatch clockface that detects drinking gestures) and provision of just-in-time text message reminders to drink when they do not meet the hourly fluid intake goal needed to achieve the recommended volume. This trial evaluates the efficacy of sipIT for increasing urine output in patients at risk for recurrence of kidney stones.

METHOD/DESIGN

Adults with a history of kidney stones and lab-verified low urine production (<2 L/day) will be randomly assigned to receive either usual care (education and encouragement to meet fluid intake guidelines) or usual care plus the sipIT intervention. The primary outcome is 24-h urine volume; secondary outcomes include urinary supersaturations, past week fluid intake, and experienced automaticity of fluid intake. Outcomes will be assessed at baseline, 1 month, 3 months, and 12 months.

CONCLUSIONS

The sipIT intervention is the first to prompt periodic fluid intake through integration of just-in-time notifications and semi-automated tracking. If sipIT is more efficacious than usual care, this intervention provides an innovative treatment option for patients needing support in meeting fluid intake guidelines for kidney stone prevention.

A rare complication in percutaneous nephrolithotomy: clinical case and implications

Percutaneous nephrolithotomy has become the standard procedure for the management of large kidney stones. Compared with other endo-urological techniques, it has a better fragmentation rate in a single session for kidney stones over 20 mm. It is therefore the recommended first-line treatment modality for large kidney stones. Bleeding is a well-known complication of this procedure, often requiring transfusion. In 0.8% of cases, bleeding can be severe, requiring surgical intervention to control hemostasis. Damage to the lumbar artery is a very rare event, and a potential complication. To our knowledge, this is the first report of lumbar artery involvement during percutaneous nephrolithotomy, complicated by severe bleeding and hemodynamic instability, necessitating conversion. Surgical exploration revealed a severed and bleeding lumbar artery. After hemostasis control by coagulation and ligation, the patient became stable. The patient was discharged on D3, where ureteroscopic lithotripsy was planned after collegial discussion with the patient. Based on this experience, it is important for the surgeon to have in mind certain principles and a thorough knowledge of the classic lateral lumbotomy approach to the kidney.

Pharmacological interventions for the management of cystinuria: a systematic review

BACKGROUND

Cystinuria is a rare genetic kidney stone disease, with no cure. Current treatments involve lowering urinary cystine levels and increasing cystine solubility. This systematic review evaluates the available literature regarding non-surgical interventions for cystinuria.

METHODS

Key electronic databases were searched for studies that described the clinical management of cystinuria with high diuresis, alkalinizing agents and thiol-based drugs that were published between 2000 and 2022. Observational studies were included if they contained clinical investigation with at least one previous or current episode of cystine stones, urine cystine levels > 250 mg/L and patients being managed with urinary dilution, alkalinizing agents or other pharmacological agents. All included studies were assessed for study design, patient characteristics and outcomes. A qualitative and critical analysis was performed whereby study quality was assessed using Methodological Index for Non-Randomized Studies (MINORS). Two authors performed the quality assessment and excluded the studies with a low MINORS score.

RESULTS

Fourteen studies met the review inclusion and quality criteria. Of the fourteen studies, two reported treatment using alkalinizing agents, six reported treatment using thiol-based drugs, and six reported combination treatment using alkalinizing agents and thiol-based drugs. These studies indicated that first-line therapies, including high fluid intake and urinary alkalinization, increased urine volume to > 3 L/day and urinary pH > 7.0, and were associated with reduced urinary cystine levels and cystine stone formation. Second-line therapy with cystine-binding thiol drugs, such as tiopronin and D-penicillamine, reduced urinary cystine levels, cystine crystal volume and increased cystine solubility, resulting in decreased cystine stone formation and stone recurrence rate. Further, combined intervention with alkalinizing agents and thiol-based drugs synergistically reduced stone recurrence.

CONCLUSION

Cystinuria treatment may require a combined approach of high diuresis, alkalinization and pharmacological interventions with regular monitoring of urinary pH, cystine levels, cystine crystal volume and solubility. However, poor adherence to treatment is relatively frequent, hence the pressing urgency for improved therapies and treatments.

Tranexamic acid for percutaneous nephrolithotomy: an abridged Cochrane review

OBJECTIVE

To assess the effects of tranexamic acid (TXA) in individuals with kidney stones undergoing percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

We performed a literature search of Cochrane Library, PubMed (including MEDLINE), Embase, Scopus, Global Index Medicus, trials registries, grey literature, and conference proceedings. We included randomised controlled trials (RCTs) that compared treatment with PCNL with administration of TXA to placebo (or no TXA) for patients aged ≥18 years. Two review authors independently classified studies and abstracted data. Primary outcomes were blood transfusion, stone-free rate (SFR), thromboembolic events (TEE). We rated the certainty of evidence (CoE) according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach using a minimally contextualised approach with pre-defined thresholds for minimally clinically important differences (MCID).

RESULTS

We included 10 RCTs assessing the effect of systemic TXA in PCNL vs placebo (or no TXA). Eight studies were published as full text. Based on an adjusted baseline risk of blood transfusion of 5.7%, systemic TXA may reduce blood transfusions (risk ratio [RR] 0.45, 95% confidence interval [CI] 0.27-0.76). Based on an adjusted baseline SFR of 75.7%, systemic TXA may increase SFR (RR 1.11, 95% CI 0.98-1.27). There is probably no difference in TEEs (risk difference 0.001, 95% CI -0.01 to 0.01). Systemic TXA may increase adverse events (AEs) (RR 5.22, 95% CI 0.52-52.72). Systemic TXA may have little to no effect on secondary interventions (RR 1.15, 95% CI 0.84-1.57). The CoE for most outcomes was assessed as low or very low.

CONCLUSIONS

Based on a body of evidence of 10 RCTs, we found that systemic TXA in PCNL may reduce blood transfusions, major surgical complications, and hospital length of stay, as well as improve the SFR; however, it may increase AEs. These findings should inform urologists and their patients in making informed decisions about the use of TXA in the setting of PCNL.

Impact of a Mediterranean diet on prevention and management of urologic diseases

Compared to a Western diet, the Mediterranean diet moves away from red meat and processed foods. Universally regarded as a healthier dietary alternative, the Mediterranean diet has garnered scientific endorsement for its ability to confer an array of compelling benefits. These health benefits encompass not only a lowered incidence of Type 2 diabetes with a reduction in obesity, but also a robust protective effect on cardiovascular health. Extensive literature exists to corroborate these health benefits; however, the impact of a Mediterranean diet on urologic diseases, specifically sexual dysfunction, lower urinary tract symptoms, stone disease, and urologic cancers are not well studied. Understanding how dietary habits may impact these urologic conditions can contribute to improved prevention and treatment strategies.A total of 955 papers from PubMed and Embase were systematically reviewed and screened. After exclusion of disqualified and duplicated studies, 58 studies consisting of randomized controlled trials, cohort studies, cross sectional studies, reviews and other meta-analyses were included in this review. 11 primary studies were related to the impact of a Mediterranean diet on sexual dysfunction, 9 primary studies regarding urinary symptoms, 8 primary studies regarding stone disease, and 9 primary studies regarding urologic cancers. All primary studies included were considered of good quality based on a New-Castle Ottawa scale. The results demonstrate a Mediterranean diet as an effective means to prevent as well as improve erectile dysfunction, nephrolithiasis, lower urinary tract symptoms, and urinary incontinence. The review highlights the need for additional research to study the impact of diet on urologic cancers and other urologic conditions such as premature ejaculation, loss of libido, female sexual dysfunction, and overactive bladder.

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.

Comparison of the bone mineral density status of patients with kidney stones stratified by stone composition

PURPOSE

Bone loss has been found to occur frequently in patients with particular metabolic disorders that are likely associated with certain kidney stone composition. Thus, we compared the bone mineral density (BMD) of patients with different kidney stone compositions.

PATIENTS AND METHODS

A total of 204 consecutive patients who exhibited stone formation with calcium oxalate (CaOx), calcium phosphate (CaP), uric acid (UA), and magnesium ammonium phosphate (MAP) underwent 24 h urine test and BMD measurement. BMD was measured by dual X-ray absorptiometry at the lumbar spine (LS) and femoral neck (FN). The Z-score was used to express BMD. A BMD Z-score ≤  - 2 was defined as a diagnostic threshold for bone loss.

RESULTS

Amongst the patients, 38 had an LS BMD Z-score of ≤  - 2, but only 2 had FN BMD Z-score of ≤  - 2. The group with an LS BMD Z-score of ≤  - 2 exhibited significantly larger male - female ratio, higher frequency of hypercalciuria and CaP, and lower frequency of MAP than the group with an LS BMD Z-score of >  - 2. Reduced LS BMD was most remarkable in the CaP group, followed by the CaOx, UA, and MAP groups. The LS BMD Z-score of hypercalciuric patients was significantly lower than that of normocalciuric patients only in the CaP group.

CONCLUSION

Patients with different kidney stone compositions presented different BMD status. Using this information may facilitate medical decision-making in patients with kidney stone who should undergone BMD earlier.

Advancements in stone classification: unveiling the beauty of urolithiasis

PURPOSE

Urolithiasis has become increasingly prevalent, leading to higher disability-adjusted life years and deaths. Various stone classification systems have been developed to enhance the understanding of lithogenesis, aid urologists in treatment decisions, and predict recurrence risk. The aim of this manuscript is to provide an overview of different stone classification criteria.

METHODS

Two authors conducted a review of literature on studies relating to the classification of urolithiasis. A narrative synthesis for analysis of the studies was used.

RESULTS

Stones can be categorized based on anatomical position, size, medical imaging features, risk of recurrence, etiology, composition, and morphoconstitutional analysis. The first three mentioned offer a straightforward approach to stone classification, directly influencing treatment recommendations. With the routine use of CT imaging before treatment, precise details like anatomical location, stone dimensions, and Hounsfield Units can be easily determined, aiding treatment planning. In contrast, classifying stones based on risk of recurrence and etiology is more complex due to dependencies on multiple variables, including stone composition and morphology. A classification system based on morphoconstitutional analysis, which combines morphological stone appearance and chemical composition, has demonstrated its value. It allows for the rapid identification of crystalline phase principles, the detection of crystalline conversion processes, the determination of etiopathogenesis, the recognition of lithogenic processes, the assessment of crystal formation speed, related recurrence rates, and guidance for selecting appropriate treatment modalities.

CONCLUSIONS

Recognizing that no single classification system can comprehensively cover all aspects, the integration of all classification approaches is essential for tailoring urolithiasis patient-specific management.

Personalized Medicine in Urolithiasis: AI Chatbot-Assisted Dietary Management of Oxalate for Kidney Stone Prevention

Accurate information regarding oxalate levels in foods is essential for managing patients with hyperoxaluria, oxalate nephropathy, or those susceptible to calcium oxalate stones. This study aimed to assess the reliability of chatbots in categorizing foods based on their oxalate content. We assessed the accuracy of ChatGPT-3.5, ChatGPT-4, Bard AI, and Bing Chat to classify dietary oxalate content per serving into low (<5 mg), moderate (5-8 mg), and high (>8 mg) oxalate content categories. A total of 539 food items were processed through each chatbot. The accuracy was compared between chatbots and stratified by dietary oxalate content categories. Bard AI had the highest accuracy of 84%, followed by Bing (60%), GPT-4 (52%), and GPT-3.5 (49%) (p < 0.001). There was a significant pairwise difference between chatbots, except between GPT-4 and GPT-3.5 (p = 0.30). The accuracy of all the chatbots decreased with a higher degree of dietary oxalate content categories but Bard remained having the highest accuracy, regardless of dietary oxalate content categories. There was considerable variation in the accuracy of AI chatbots for classifying dietary oxalate content. Bard AI consistently showed the highest accuracy, followed by Bing Chat, GPT-4, and GPT-3.5. These results underline the potential of AI in dietary management for at-risk patient groups and the need for enhancements in chatbot algorithms for clinical accuracy.

Mixed stones: urinary stone composition, frequency and distribution by gender and age

Proper analysis of urinary stone composition is a cornerstone for diagnosis, targeted treatment and recurrence prevention of urolithiasis. The aim of this study was to determine the composition, frequency and distribution of mixed stones according to gender and age of patients. A total of 42,519 urinary stones from 30,311 men and 12,208 women submitted between January 2007 and December 2020 were studied. Most urinary calculi consisted of two components (50.9%), followed by stones of a single constituent (27.1%) and three-component stones (21.9%), while four-component stones were only rarely identified (0.1%). Among all stones, 49.8% consisted of whewellite (COM), weddellite (COD), and mixtures of COM and COD, 33.8% were pure carbonate apatite (CA) and mixtures of CA with COM and/or COD, while 7.6% were composed of uric acid anhydrous (UAA), uric acid dihydrate (UAD), and mixed UAA and UAD. The remaining 8.8% of calculi were rare single-component stones and rare mixtures of various constituents. The number of stone components was inversely associated with age (p < 0.001). The proportion of men decreased significantly with the number of stone constituents, from 3.01:1 for single-component stones to 1.0:1 for four-component urinary calculi (p < 0.001). The vast majority of urinary calculi consisted of two or more components in varying proportions. While age was inversely associated with the number of stone constituents, the proportion of women increased significantly from single-component to four-component urinary calculi. A significant proportion of mixed stones could present a challenge for diagnosis and targeted recurrence prevention.

Leveraging behavioral modification technology for the prevention of kidney stones

PURPOSE OF REVIEW

The purpose of this review is to examine the use of technology to help promote and maintain behaviors that decrease stone recurrence.

RECENT FINDINGS

Behavior change is a complex process with various interacting components. Recent developments have sought to utilize technology in combination with behavioral change techniques to promote behavior that lowers stone recurrence risk. Smart water bottles are becoming a popular way to accurately measure fluid intake with variable impact on adherence to the recommended daily fluid intake. Mobile apps have also been explored as a method to improve fluid intake. Interventions that combine smart water bottles, mobile apps, and behavioral change techniques have shown the most promise in promoting increased daily fluid intake. Other technologies, such as smart pill dispensers and hydration monitors, have potential applications in promoting behavioral change for stone disease but have yet to be evaluated for this purpose.

SUMMARY

There is a limited number of studies exploring technology as a means to promote and maintain behaviors that decrease urinary stone recurrence. Future research is needed to elucidate how to maximize the potential of these technologies and better understand which behavioral change techniques best promote habit formation for the prevention of stones.

Stevens-Johnson Syndrome From Combined Allopurinol and Angiotensin-Converting Enzyme Inhibitors: A Narrative Review

Stevens-Johnson syndrome (SJS) is a severe and potentially debilitating skin reaction frequently related to medication use. Allopurinol and angiotensin-converting enzyme (ACE) inhibitors are commonly prescribed medications for prevalent health conditions worldwide, and their interaction associated with SJS warrants further investigation. A comprehensive literature search was performed to investigate cases as studies related to SJS occurring in patients with concomitant use of allopurinol and ACE inhibitors. We identified case reports and studies detailing hypersensitivity reactions, including SJS, attributed to a combination of allopurinol and ACE inhibitors. Despite the drug-drug interactions or lack thereof seen in patient populations, there is no definitive evidence of a pharmacokinetic interaction between allopurinol and ACE inhibitors. We were only able to find one case report specifically detailing SJS in a patient on combined ACE inhibitors and allopurinol. While the exact mechanism of the interaction is unclear, those reported cases of severe hypersensitivity reactions suggest a previous history of impaired renal function as a predisposing factor in the development of SJS. The potential risk of SJS with coadministration of ACE inhibitors and allopurinol is a drug-drug interaction that physicians should be aware of. This topic requires additional attention to determine if this drug combination should be avoided entirely in certain patients.

Pharmacologic treatment of kidney stones: Current medication and pH monitoring

Nephrolithiasis is a globally prevalent urologic condition associated with significant morbidity and patient discomfort. Current management of kidney stones includes both surgical and pharmacologic interventions. Though surgery may be necessary under certain circumstances, pharmacologic treatment is a more affordable, readily available, and a less invasive option for patients. A comprehensive scoping review was conducted to summarize the available literature on the pharmacologic strategies for managing the predominant stone types including calcium oxalate, calcium phosphate, uric acid, struvite, and cystine stones. Central to these therapeutic approaches is the regulation of factors such as urine pH, stone crystallization, and patient metabolics that precipitate stone development and growth. This review highlights the pharmacological options available for treating each kidney stone type, emphasizing the importance of patient tailored medical management that should be considered by every physician.

Mobile and eHealth technologies in the management and prevention of nephrolithiasis: A systematic review

INTRODUCTION

Kidney stone disease (KSD) is a common urological condition that often requires long-term care. Mobile health (mHealth) and eHealth technologies have the potential to enhance chronic disease management and behavioral change. To assess opportunities to apply these tools to improve KSD treatment and prevention, we aimed to assess current evidence on the use, benefits, and limitations of mHealth and eHealth in KSD.

METHODS

We performed a systematic review of primary research studies of mHealth and eHealth in the evaluation and management of KSD. Two independent researchers screened citations by title and abstract for relevance, then full-text review was performed for descriptive summary of the studies.

RESULTS

A total of 37 articles were included for analysis. Primary domains of evidence included: 1) "smart" water bottles and mobile-device apps for tracking fluid consumption, which showed increased intake in most studies; 2) ureteral stent tracking platforms, which improved the rate of long-term retained stents; 3) virtual stone clinics, which have been suggested to increase access, lower costs, and have satisfactory outcomes; 4) smartphone-based endoscopy platforms, which offered cost-effective image quality in resource-limited settings; 5) patient information about KSD online, which was typically characterized as poor quality and/or accuracy, particularly on YouTube. Most studies were proof-of-concept or single-arm intervention designs, with limited assessment of effectiveness or long-term clinical outcomes.

CONCLUSIONS

Mobile and eHealth technologies have significant real-world applications to KSD prevention, intervention, and patient education. A lack of rigorous effectiveness studies currently limits evidence-based conclusions and incorporation in clinical guidelines.

A Systematic Scoping Review of Comparative Effectiveness Studies in Kidney Stone Disease

OBJECTIVE

To review the status of comparative effectiveness studies for kidney stone disease with focus on study outcome, type, population, time trends, and patient-centered approaches.

METHODS

A systematic scoping review was performed for articles published between January 1, 2005, and March 30, 2021, using keywords relevant to kidney stone disease. Studies published in English that compared two or more alternative methods for prevention, diagnosis, treatment, monitoring, or care delivery were included. Two reviewers independently reviewed abstracts and an arbitrator resolved discrepancies. Nine reviewers abstracted information from full-length studies. Descriptive statistics were summarized, and linear regression was performed to evaluate temporal trends of study characteristics.

RESULTS

We reviewed 1773 abstracts and 707 full-length manuscripts focused on surgical intervention (440); medical expulsive therapy (MET) (152); analgesic control (80); and homeopathic, diagnostics, and/or prophylaxis (84). Randomized controlled trials were common across all outcome categories, including surgery (41.6%), MET (60.2%), analgesic control (81.3%), homeopathic (41.2%), diagnostic (47.6%), and prophylaxis (49.1%). Patient-reported outcomes were utilized in 71.7% and 95% of MET and analgesic control studies, respectively, but in the minority of all other study themes. Over time, meta-analyses and multicenter studies increased [P < .001].

CONCLUSION

Surgical and MET themes dominate published comparative literature in kidney stone disease. There is substantial variation in use of patient-reported outcomes across surgical themes. Multicentered studies and those generating higher level evidence have increased over time but opportunities exist to improve collaborative, high-quality, and patient-centered research in kidney stone disease.

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

Felbamate urolithiasis

Drug-induced nephrolithiasis is an important consideration in recurrent stone formers with polypharmacy. While felbamate nephrolithiasis has previously been published in the paediatric population, we present the oldest published case of a felbamate stone in an adult, a man in his 30s with Lennox-Gastaut syndrome. Even with moderate dosing, high drug serum levels can occur. Performing at least one stone analysis remains a critical component to care in these patients. Urologists should have a high index of suspicion for drug stone when stone analysis returns indeterminate characterisation in the absence of infection. Close communication with neurology is key to preventing recurrent stone disease.

Pediatric renal lithiasis in Spain: research, diagnostic and therapeutic challenges, and perspectives

Incidence and prevalence of urolithiasis is apparently increasing worldwide, also among children and adolescents. Nevertheless, robust data have only been obtained in a few countries. In Spain, a voluntary Registry for Pediatric Renal Lithiasis has been active since 2015. Irregular participation limits its applicability, as well as its limitation to patients with a stone available for morphocompositional study, to obtain data about incidence and prevalence. On the other hand, findings about typology of stones and clinical and analytical characteristics of these subjects have been communicated in several meetings. Other valuable efforts in this field are the elaboration of guidelines for the collection and processing of urine samples for the study of urolithiasis in pediatric patients with the consensus of the Spanish Society for Pediatric Nephrology (AENP) as well as the Spanish Society for Laboratory Medicine (SEQC), the collaborative network RenalTube for the diagnosis of primary tubulopathies and the registry of patients with Primary Hyperoxaluria (OxalSpain). In many hospitals from the public healthcare system, pediatric nephrologists are the specialists in charge of the management of children with kidney stones, but there is no formal regulation on this competence. Other specialists, such as urologists, pediatric surgeons or pediatric urologists, in many cases do not offer a complete insight into the etiopathogenic mechanisms and the consequent medical treatment. Access to medication according to standards of treatment is warranted, provided a correct diagnosis is achieved, but criteria for the reimbursement of certain therapies, such as RNAi drugs for primary hyperoxaluria, are arguable.

Is stone free status really necessary for metabolic evaluation following stone removal procedures?

OBJECTIVE

To evaluate the impact of stone free status on the outcomes of metabolic evaluation in recurrent stone formers after ureteroscopic stone removal.

PATIENTS AND METHODS

A total of 78 patients undergoing retrograde intrarenal surgery (RIRS) for renal stones were included and cases were divided into two groups after 4 weeks based on the NCCT findings. While cases in the Group 1 (n = 54) was completely stone free, cases in Group 2 (n = 24) had residual fragments in the kidney. A full 24-h urine analysis for relevant stone forming risk factors has been performed after 4 weeks following the fURS procedures in all patients of both groups. Outcomes of metabolic evaluation (24-h urine and serum) have been comparatively evaluated in both groups.

RESULTS

Evaluation of the preoperative serum and urine stone forming risk factors revelaed no statistical difference in both groups. Comparative evaluation of the 24-h urinary stone forming risk factors also revealed no statistically significant difference between preoperative and postoperative findings in cases of Group 2 with residual stones. Last but not least, no significant difference was observed between the mean preoperative and postoperative serum variables between two groups.

CONCLUSIONS

Our results show that in the light of the similar metabolic evaluation outcomes obtained in cases with and without residual fragments, 'stone free status' may not be an essential factor to perform a detailed metabolic evaluation (24-h urine analysis and serum parameters) after endourological stone removal procedures.

Drivers of calcium oxalate stone formation in the octogenarian population

INTRODUCTION

American Urological Association (AUA) guidelines suggest metabolic testing via 24-h urine studies in high-risk, interested first-time stone formers, and recurrent stone formers. If metabolic testing is not available or otherwise not feasible, clinicians may need to utilize empiric therapy. Debility and social barriers, particularly in the elderly population, may limit the practicality of metabolic testing, and therefore, empiric therapy is of particular importance. The aim of this study is to identify whether unique urinary metabolic abnormality profiles exist for octogenarians with calcium oxalate kidney stones, as this may guide empiric stone prevention therapy more precisely in this population.

MATERIALS AND METHODS

Patients with calcium oxalate stones from a single academic kidney stone center in New York, NY, were retrospectively identified in our prospectively managed database. Patient data, including demographic, clinical information, and baseline 24-h urine studies, were collected before initiating any treatment. Subjects were stratified by age (≤ 40, 41-59, 60-79, and ≥ 80 years) to compare the metabolic urinary abnormality profiles between octogenarians and other age groups. Subgroup analyses were also performed to compare results by gender and by the presence of underlying kidney dysfunction. Comparative statistical analysis was carried out using Chi-square tests, Mann-Whitney U tests, and t-tests where appropriate.

RESULTS

Hypocitraturia, low urine pH, and low urine volume were most common in older patients, particularly in octogenarians. Hypercalciuria, hypernatriuria, and hyperuricosuria were more apparent in younger groups.

CONCLUSION

With increasing age, hypocitraturia, low urine pH, and low urine volume were more prevalent on 24-h urine metabolic testing. We hypothesize increased comorbidity, including medical renal disease, polypharmacy, and dehydration are possible factors contributing to this unique profile. We suggest that empiric therapy targeted towards this profile is important in very elderly stone formers in whom 24-h urine testing may not be possible. Increased hydration, increased fruit and vegetable intake, and low-dose alkali therapy are easy measures to accomplish this.

POCUS-first for nephrolithiasis: A Monte Carlo simulation illustrating cost savings, LOS reduction, and preventable radiation

OBJECTIVES

Non-contrast computed tomography (NCCT) is the gold standard for nephrolithiasis evaluation in the emergency department (ED). However, Choosing Wisely guidelines recommend against ordering NCCT for patients with suspected nephrolithiasis who are <50 years old with a history of kidney stones. Our primary objective was to estimate the national annual cost savings from using a point-of-care ultrasound (POCUS)-first approach for patients with suspected nephrolithiasis meeting Choosing Wisely criteria. Our secondary objectives were to estimate reductions in ED length of stay (LOS) and preventable radiation exposure.

METHODS

We created a Monte Carlo simulation using available estimates for the frequency of ED visits for nephrolithiasis and eligibility for a POCUS-first approach. The study population included all ED patients diagnosed with nephrolithiasis. Based on 1000 trials of our simulation, we estimated national cost savings in averted advanced imaging from this strategy. We applied the same model to estimate the reduction in ED LOS and preventable radiation exposure.

RESULTS

Using this model, we estimate a POCUS-first approach for evaluating nephrolithiasis meeting Choosing Wisely guidelines to save a mean (±SD) of $16.5 million (±$2.1 million) by avoiding 159,000 (±18,000) NCCT scans annually. This resulted in a national cumulative decrease of 166,000 (±165,000) annual bed-hours in ED LOS. Additionally, this resulted in a national cumulative reduction in radiation exposure of 1.9 million person-mSv, which could potentially prevent 232 (±81) excess cancer cases and 118 (±43) excess cancer deaths annually.

CONCLUSION

If adopted widely, a POCUS-first approach for suspected nephrolithiasis in patients meeting Choosing Wisely criteria could yield significant national cost savings and a reduction in ED LOS and preventable radiation exposure. Further research is needed to explore the barriers to widespread adoption of this clinical workflow as well as the benefits of a POCUS-first approach in other patient populations.

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.

Underdiagnosis of Hyperparathyroidism in Patients With Nephrolithiasis in a Community Setting

Objective Untreated primary hyperparathyroidism (PHPT) has wide-ranging multisystemic effects. Recent studies based in the US have shown a less than 25% screening rate for PHPT. Our study aims to detect whether similar deficiencies exist in our community healthcare system while quantifying the prevalence of PHPT underdiagnosis and inadequate surgical referrals. Study design This retrospective quantitative study enrolled patients aged ≥18 years with imaged-confirmed nephrolithiasis at our healthcare facilities from 2017 to the present (n=2021). Patients with documented calcium levels and kidney/ureter stones were included. Descriptive and univariate analyses were performed. Results A total of 2021 subjects met the criteria to be enrolled in the study. 26.6% (n=537) of patients with nephrolithiasis had elevated calcium levels on record. 13.6% (n=73) of hypercalcemic patients were screened for PHPT with an intact parathyroid hormone (PTH). A majority (63%, n=46) of patients with intact PTH had PHPT defined as PTH levels >55 pg/mL. Ultimately, only 19.6% (n=9) of patients with PHPT were referred for surgical intervention, and there was no significant difference in referral rate between patients with PHPT and those without (p=0.913). Conclusions PHPT is underdiagnosed in our community, leading to a significantly low rate of surgical referral and delay in management. Implementation of hospital protocols to aid in improving diagnosis and interventions could improve outcomes for PHPT patients.

A Green Prescription: Integrating Environmental Sustainability in Urology Guidelines

Against the background of the climate crisis, there is an urgent need to include environmental sustainability recommendations in clinical practice guidelines. We highlight five domains for which suitable recommendations could help in mitigating the environmental impact of urology practice. PATIENT SUMMARY: Climate change is an urgent issue that requires global action. Guidelines published by urological societies should include recommendations for minimizing the impact of urology practice on the environment.

Predictive value of single-nucleotide polymorphism signature for nephrolithiasis recurrence: a 5-year prospective study

Background

Genetic variations are linked to kidney stone formation. However, the association of single nucleotide polymorphism (SNPs) and stone recurrence has not been well studied. This study aims to identify genetic variants associated with kidney stone recurrences and to construct a predictive nomogram model using SNPs and clinical features to predict the recurrence risk of kidney stones.

Methods

We genotyped 49 SNPs in 1001 patients who received surgical stone removal between Jan 1 and Dec 31 of 2012. All patients were confirmed stone-free by CT scan and then received follow-up at least 5 years. SNP associations with stone recurrence were analyzed by Cox proportion hazard model. A predictive nomogram model using SNPs and clinical features to predict the recurrence risk of kidney stones was developed by use of LASSO Cox regression.

Results

The recurrence rate at 3, 5, 7 years were 46.8%, 71.2%, and 78.4%, respectively. 5 SNPs were identified that had association with kidney stone recurrence risk. We used computer-generated random numbers to assign 500 of these patients to the training cohort and 501 patients to the validation cohort. A nomogram that combined the 14-SNPs-based classifier with the clinical risk factors was constructed. The areas under the curve (AUCs) at 3, 5 and 7 years of this nomogram was 0.645, 0.723, and 0.75 in training cohort, and was 0.631, 0.708, and 0.727 in validation cohort, respectively. Results show that the nomogram presented a higher predictive accuracy than those of the SNP classifier or clinical factors alone.

Conclusion

SNPs are significantly associated with kidney stone recurrence and should add prognostic value to the traditional clinical risk factors used to assess the kidney stone recurrence. A nomogram using clinical and genetic variables to predict kidney stone recurrence has revealed its potential in the future as an assessment tool during the follow-up of kidney stone patients.

2022 Recommendations of the AFU Lithiasis Committee: Medical management - from diagnosis to treatment

The morphological-compositional analysis of urinary stones allows distinguishing schematically several situations: dietary, digestive, metabolic/hormonal, infectious and genetic problems. Blood and urine testing are recommended in the first instance to identify risk factors of urinary stone disease in order to avoid recurrence or progression. The other objective is to detect a potential underlying pathology associated with high risk of urinary stone disease (e.g. primary hyperparathyroidism, primary or enteric hyperoxaluria, cystinuria, distal renal tubular acidosis) that may require specific management. Lifestyle-diet measures are the basis of the management of all stone types, but pharmacological treatments may be required. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

Mendelian Randomization Analysis of Genetic Proxies of Thiazide Diuretics and the Reduction of Kidney Stone Risk

Importance

Clinical trial data have called into question the efficacy of thiazide diuretics for the prevention of kidney stones.

Objective

To identify whether there is an association between genetic proxies of thiazide diuretics and the risk of kidney stones.

Design, Setting, and Participants

This genetic association study undertook a mendelian randomization analysis of derived exposures and outcomes from genome-wide association study summary statistics. Genetic proxies of thiazide diuretics were derived from the International Consortium for Blood Pressure. Kidney stone cases and controls were derived from the Million Veteran Program, UK Biobank, and the FinnGen study. These cross-sectional designs do not report a duration of follow-up. Data analysis was performed in May 2023.

Exposure

Genetic proxies of thiazide diuretics were genetic variants in the thiazide-sensitive sodium chloride cotransporter gene associated with systolic blood pressure. Genetic proxies of β-blockers and systolic blood pressure served as negative controls.

Main Outcomes and Measures

The main outcome was the odds of kidney stones. The secondary outcomes were serum laboratory values relevant to the treatment of kidney stones.

Results

The main analysis included up to 1 079 657 individuals, including 50 832 kidney stone cases and 1 028 825 controls. In a meta-analysis of all cohorts, genetic proxies of thiazide diuretics were associated with a lower odds of kidney stones (OR, 0.85; 95% CI, 0.81-0.89; P < .001). Genetic proxies of β-blockers (OR, 1.02; 95% CI, 0.96-1.07; P = .52) and systolic blood pressure (OR, 1.00; 95% CI, 1.00-1.01; P = .49) were not associated with kidney stones. Genetic proxies of thiazide diuretics were associated with higher serum calcium (β [SE], 0.051 [0.0092]; P < .001) and total cholesterol (β [SE], 0.065 [0.015]; P < .001), but lower serum potassium (β [SE], -0.073 [0.022]; P < .001).

Conclusions and Relevance

In this genetic association study, genetic proxies of thiazide diuretics were associated with reduced kidney stone risk. This finding reflects a drug effect over the course of a lifetime, unconstrained by the limited follow-up period of clinical trials.

Patient compliance for metabolic evaluation and medical treatment (CoMET) in calcium-oxalate stone patients: prospective study by EULIS eCORE study group

PURPOSE

In this study, we aimed to identify the compliance rates of calcium-oxalate stone patients for metabolic evaluation, diet and medical treatment and also determine the factors that are associated with poor compliance rates.

METHODS

This study was conducted by the EULIS eCORE working group prospectively. In the initial visit, demographic and stone-related characteristics were recorded. Patients were suggested metabolic evaluation, dietary advices and medical treatment. Follow-up visit was performed after 3 months and compliance rates were recorded. Logistic regression analysis was performed to determine factors associated with poor compliance to metabolic evaluation, diet and medical treatment.

RESULTS

Data of 346 patients from nine centers were analyzed. Compliance rates were 71.7%, 65.3%, and 63.7% for metabolic evaluation, diet, and medical treatment, respectively. In multivariate analysis, level of education (p = 0.003), history of emergency department visit (p = 0.04), number of stone surgeries (p = 0.03), patient care in dedicated stone clinic (p = 0.03), and history of shock wave lithotripsy (p = 0.005) were detected as independent predictors of compliance to metabolic analysis. Level of education (p < 0.001) and history of emergency department visit (p = 0.01) were detected as independent predictors of patient compliance to diet. Number of stone episodes (p = 0.03), family history of stones (p = 0.02), and polypharmacy (p < 0.001) were detected as independent predictors of patient compliance to medical treatment.

CONCLUSIONS

Patient compliance to metabolic evaluation, diet, and medical therapy is important for successful management of urolithiasis. Dietary advices and medications should be personalized by taking in to account the factors associated with poor compliance.

[Imaging for urolithiasis]

The substantial reduction of radiation exposure using (ultra-)low dose programs in native computed tomographic imaging has led to considerable changes in imaging diagnostics and treatment planning in urolithiasis in recent years. In addition, especially in Germany, ultrasound diagnostics is highly available in terms of equipment and with increasing expertise. This can largely replace the previous radiation-associated procedures in emergency and follow-up diagnostics, but also in intraoperative imaging, e.g., in percutaneous stone therapy (intraoperative fluoroscopy). This is reflected in the international guidelines, which recommend these two modalities as first-line diagnostics in all areas mentioned. Continuous technical development enables ever higher resolution imaging and thus improved diagnostics with high sensitivity and specificity. This also enables reliable imaging of particularly vulnerable patient groups, such as children or pregnant women. In addition, methods from the field of artificial intelligence (AI; machine learning, deep learning) are increasingly being used for automated stone detection and stone characterization including its composition. Furthermore, AI models can provide prognosis models as well as individually tailored treatment, follow-up, and prophyaxis. This will enable further personalization of diagnostics and therapy in the field of urolithiasis.

Tranexamic acid for percutaneous nephrolithotomy

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is the gold standard for the treatment of large kidney stones but comes with an increased risk of bleeding compared to other treatments, such as ureteroscopy and shock wave lithotripsy. Tranexamic acid (TXA) is an antifibrinolytic agent that has been used to reduce bleeding complications in other settings.

OBJECTIVES

To assess the effects of TXA in individuals with kidney stones undergoing PCNL.

SEARCH METHODS

We performed a comprehensive literature search of the Cochrane Library, PubMed (including MEDLINE), Embase, Scopus, Global Index Medicus, trials registries, other sources of the grey literature, and conference proceedings. We applied no restrictions on the language of publication nor publication status. The latest search date was 11 May 2023.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared treatment with PCNL with administration of TXA to placebo (or no TXA) for patients ≥ 18 years old.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified studies and abstracted data. Primary outcomes were: blood transfusion, stone-free rate (SFR), and thromboembolic events (TEEs). Secondary outcomes were: adverse events (AEs), secondary interventions, major surgical complications, minor surgical complications, unplanned hospitalizations or readmissions, and hospital length of stay (LOS). We performed statistical analyzes using a random-effects model. We rated the certainty of evidence (CoE) according to the GRADE approach using a minimally contextualized approach with predefined thresholds for minimally clinically important differences (MCIDs).

MAIN RESULTS

We analyzed 10 RCTs assessing the effect of systemic TXA in PCNL versus placebo (or no TXA) with 1883 randomized participants. Eight studies were published as full text. One was published in abstract proceedings, but it was separated into two separate studies for the purpose of our analyzes. Average stone surface area ranged 3.45 to 6.62 cm2. We also found a single RCT published in full text assessing the effects of topical TXA in PCNL versus placebo (or no TXA) with 400 randomized participants, the results of which are further described in the review. Here we focus only on the results of TXA used systemically. Blood transfusion - Based on a representative baseline risk of 5.7% for blood transfusions taken from a large presentative observational studies, systemic TXA may reduce blood transfusions (risk ratio (RR) 0.45, 95% confidence interval (CI) 0.27 to 0.76; I2 = 28%; 9 studies, 1353 participants; low CoE). We assumed an MCID of ≥ 2%. Based on 57 participants per 1000 with placebo (or no TXA) being transfused, this corresponds to 31 fewer (from 42 fewer to 14 fewer) participants being transfused per 1000. Stone-free rate - Based on a representative baseline risk of 75.7% for SFR, systemic TXA may increase SFRs (RR 1.11, 95% CI 0.98 to 1.27; I2 = 62%; 4 studies, 603 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 757 participants per 1000 being stone free with placebo (or no TXA), this corresponds to 83 more (from 15 fewer to 204 more) stone-free participants per 1000. Thromboembolic events - There is probably no difference in TEEs (risk difference (RD) 0.00, 95% CI -0.01 to 0.01; I2 = 0%; 6 studies, 841 participants; moderate CoE). We assumed an MCID of ≥ 2%. Since there were no thromboembolic events in intervention and/or control groups in 5 out of6 studies, we opted to assess a risk difference with systemic TXA for this outcome. Adverse events - Systemic TXA may increase AEs (RR 5.22, 95% CI 0.52 to 52.72; I2 = 75%; 4 studies, 602 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 23 participants per 1000 with placebo (or no TXA) having an adverse event, this corresponds to 98 more (from 11 fewer to 1000 more) participants with adverse events per 1000. Secondary interventions - Systemic TXA may have little to no effect on secondary interventions (RR 1.15, 95% CI 0.84 to 1.57; I2 = 0%; 2 studies, 319 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 278 participants per 1000 with placebo (or no TXA) having a secondary intervention, this corresponds to 42 more (from 44 fewer to 158 more) participants with secondary interventions per 1000. Major surgical complications - Based on a representative baseline risk for major surgical complications of 4.1%, systemic TXA may reduce major surgical complications (RR 0.36, 95% CI 0.21 to 0.62; I2 = 0%; 5 studies, 733 participants; moderate CoE). We assumed an MCID of ≥ 2%. Based on 41 participants per 1000 with placebo (or no TXA) having a major surgical complication, this corresponds to 26 fewer (from 32 fewer to 16 fewer) participants with major surgical complications per 1000. Minor surgical complications - Systemic TXA may reduce minor surgical complications (RR 0.71, 95% CI 0.45 to 1.10; I2 = 76%; 5 studies, 733 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 396 participants per 1000 with placebo (or no TXA) having a minor surgical complication, this corresponds to 115 fewer (from 218 fewer to 40 more) participants with minor surgical complications per 1000. Unplanned hospitalizations or readmissions - We are very uncertain how unplanned hospitalizations or readmissions are affected (RR 1.55, 95% CI 0.45 to 5.31; I2 = not applicable; 1 study, 189 participants; very low CoE). We assumed an MCID of ≥ 2%. Hospital length of stay - Systemic TXA may reduce hospital LOS (mean difference 0.52 days lower, 95% CI 0.93 lower to 0.11 lower; I2 = 98%; 7 studies, 1151 participants; low CoE). We assumed an MCID of ≥ 0.5 days.

AUTHORS' CONCLUSIONS

Based on 10 RCTs with substantial methodological limitations that lowered all CoE of effect, we found that systemic TXA in PCNL may reduce blood transfusions, major and minor surgical complications, and hospital LOS, as well as improve SFRs; however, it may increase AEs. We are uncertain about the effects of systemic TXA on other outcomes. Findings of this review should assist urologists and their patients in making informed decisions about the use of TXA in the setting of PCNL.

Examination of nutritional factors associated with urolithiasis risk in plant based meat alternatives marketed to children and infants

INTRODUCTION

The global prevalence of pediatric nephrolithiasis continues to rise amidst increased sodium and animal protein intake. Plant-based meat alternatives (PBMAs) have recently gained popularity due to health benefits, environmental sustainability, and increased retail availability. PBMAs have the potential to reduce the adverse metabolic impact of animal protein on kidney stone formation. We analyzed PBMAs targeted to children to characterize potential lithogenic risk vs animal protein.

METHODS

We performed a dietary assessment using a sample of PBMAs marketed to or commonly consumed by children and commercially available at national retailers. Nutrient profiles for PBMAs were compiled from US Department of Agriculture databases and compared to animal protein sources using standardized serving sizes. We also analyzed nutrient profiles for plant-based infant formulas against typical dairy protein-based formulas. Primary protein sources were identified using verified ingredient lists. Oxalate content was extrapolated from dietary data sources.

RESULTS

A total of 41 PBMAs were analyzed: chicken (N = 18), hot dogs (N = 3), meatballs (N = 5), fish (N = 10), and infant formula (N = 5). Most products (76%) contained a high-oxalate ingredient as the primary protein source (soy, wheat, or almond). Average oxalate content per serving was substantially higher in these products (soy 11.6 mg, wheat 3.8 mg, almond 10.2 mg) vs animal protein (negligible oxalate). PBMAs containing pea protein (24%) had lower average oxalate (0.11 mg). Most PBMAs averaged up to six times more calcium and three times more sodium per serving compared to their respective animal proteins. Protein content was similar for most categories.

CONCLUSIONS

Three-quarters of the examined plant-based meat products for children and infants contain high-oxalate protein sources. Coupled with higher per-serving sodium and calcium amounts, our findings raise questions about possible lithogenic risk in some PBMAs, and further studies are needed to assess the relationship between PBMAs and nephrolithiasis.

Vitamins as regulators of calcium-containing kidney stones - new perspectives on the role of the gut microbiome

Calcium-based kidney stone disease is a highly prevalent and morbid condition, with an often complicated and multifactorial aetiology. An abundance of research on the role of specific vitamins (B6, C and D) in stone formation exists, but no consensus has been reached on how these vitamins influence stone disease. As a consequence of emerging research on the role of the gut microbiota in urolithiasis, previous notions on the contribution of these vitamins to urolithiasis are being reconsidered in the field, and investigation into previously overlooked vitamins (A, E and K) was expanded. Understanding how the microbiota influences host vitamin regulation could help to determine the role of vitamins in stone disease.

Atypical clinical presentation and management of urinary stone disease in non-verbal non-ambulatory children

INTRODUCTION

Management of kidney stones primarily depends on various factors such as the presence of urinary tract obstruction, pain, stone size, location, impact on renal function, and the existence of infection. Renal colic is the classic presentation of an obstructive kidney stone. However, in this study, we present a cohort of non-verbal non-ambulatory (NVNA) patients who exhibit a distinct and uncommon presentation of kidney stones due to their medical conditions. Information about kidney stone disease in this gropup of complex pediatric patients is, scarce and their associated risk factors are not well understood. Therefore, we aim to summarize the clinical presentation, and management challenges in this unique group of NVNA patients to identify potential variables for prospective studies.

METHODS

A retrospective chart review was completed for all NVNA patients seen at the pediatric multidisciplinary kidney stone clinic between July 2020 to August 2022. Demographic variables, clinical presentation data, metabolic evaluation, radiological imaging, and surgical management was included for analysis.

RESULTS

A total of 224 pediatric patients were referred to the multidisciplinary stone clinic. Of those, 27 were identified to be NVNA. The most common primary diagnosis was Cerebral Palsy followed by Lennox-Gastaut syndrome. Average age at first kidney stone presentation was 11.5 years ± 5.7 years. An obstructing stone was diagnosed in 18 (66%) patients, 4 (22.2%) of these presented with sepsis. Average stone burden was 9.2 mm ( ± 5.8 mm). Of the obstructing stones, 13 (72%) were in the kidney. All patients with an obstructing stone underwent surgical management with retrograde endoscopic approach. Metabolic 24-h-urine analysis was completed in 24 (89%) patients. 17 (62%) had an elevated urine density, 15 (55%) demonstrated calcium oxalate supersaturation, 12 (44%) met criteria for acidosis, and 7 (26%) had significant hypocitraturia.

DISCUSSION

NVNA patients represent a unique cohort whose clinical presentation is atypical. Limited ability to express symptoms makes early detection difficult to recognize. Twenty two percent of patients present with sepsis as their first manifestation of an acutely obstructing kidney stone. Pain is subjectively interpreted by caregivers and is an uncommon symptom. Our cohort demonstrates common risk factors for stones including propensity for chronic dehydration, slow urinary tract transit, ineffective bladder emptying, G-tube feeding, and lithogenic medications.

CONCLUSION

NVNA pediatric patients have atypical kidney stone clinical presentation. Awareness of this unique group of patients should support future collaborative studies to focus on understanding these atypical presentations and reflect on improving management.

Lifestyle factors, serum parameters, metabolic comorbidities, and the risk of kidney stones: a Mendelian randomization study

Background and objective

The early identification of modifiable risk factors is important for preventing kidney stones but determining causal associations can be difficult with epidemiological data. We aimed to genetically assess the causality between modifiable factors (lifestyle factors, serum parameters, and metabolic comorbidities) and the risk of kidney stones. Additionally, we aimed to explore the causal impact of education on kidney stones and its potential mediating pathways.

Methods

We conducted a two-sample Mendelian randomization (MR) study to explore the causal association between 44 modifiable risk factors and kidney stones. The FinnGen dataset initially explored the causal relationship of risk factors with kidney stones and the UK Biobank dataset was used as the validation set. Then, a meta-analysis was conducted by combining discovery and validation datasets. We used two-step MR to assess potential mediators and their mediation proportions between education and kidney stones.

Results

The combined results indicated that previous exposures may increase the risk of kidney stones, including sedentary behavior, urinary sodium, the urinary sodium/potassium ratio, the urinary sodium/creatinine ratio, serum calcium, 25-hydroxyvitamin D (25OHD), the estimated creatinine-based glomerular filtration rate (eGFRcrea), GFR estimated by serum cystatin C (eGFRcys), body mass index (BMI), waist circumference, type 2 diabetes mellitus (T2DM), fasting insulin, glycated hemoglobin, and hypertension. Coffee intake, plasma caffeine levels, educational attainment, and the urinary potassium/creatinine ratio may decrease the risk of kidney stones. Ranked by mediation proportion, the effect of education on the risk of kidney stones was mediated by five modifiable risk factors, including sedentary behavior (mediation proportion, 25.7%), smoking initiation (10.2%), BMI (8.2%), T2DM (5.8%), and waist circumference (3.2%).

Conclusion

This study provides MR evidence supporting causal associations of many modifiable risk factors with kidney stones. Sedentary lifestyles, obesity, smoking, and T2DM are mediating factors in the causal relationship between educational attainment and kidney stones. Our results suggest more attention should be paid to these modifiable factors to prevent kidney stones.

'Like a ticking time bomb': A qualitative study exploring the illness experiences of adults with kidney stone disease

OBJECTIVE

Kidney stone disease (KSD) is a common, complex and painful urological condition, but how patients make sense of and respond to the challenges of KSD is poorly understood. Using the common-sense model of illness self-regulation (CSM-SR), we aimed to explore the illness experiences of individuals with KSD.

DESIGN

A qualitative design using individual semi-structured interviews.

METHODS

Thirty-three patients with KSD attending outpatient urology services participated in interviews informed by the CSM-SR. Data were analysed using reflexive thematic analysis. Themes were mapped onto the domains of the CSM-SR.

RESULTS

Five main themes were generated, broadly echoing domains within the CSM-SR: (1) making sense of KSD, (2) normality paused, (3) the psychological burden of KSD, (4) the tensions of managing KSD, and (5) improving understanding of KSD. Additionally, findings suggested that partners' perceptions of KSD were an additional contextual factor that informed patients' own perceptions and management of KSD. Participants appraised initial KSD symptoms as indicative of a serious health threat. Diagnosis brought some relief, however, KSD wielded multi-dimensional impacts on patients' perceptions, self-management and well-being. Anxiety, including fear of KSD recurrence, and low mood were common psychological burdens across narratives.

CONCLUSION

The majority of the themes identified were commensurate with an extended CSM-SR. This model has utility in informing how patients perceive and manage KSD. Examining patients' KSD representations and routinely assessing for psychological distress may be of benefit to improve health outcomes for this patient group.

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.

Voided volume may not impact stone outcomes: Review of a large institutional nephrolithiasis cohort

Background

Urologic guidelines universally recommend increasing fluid intake for kidney stone prevention. Increased voided volume is thought to help reduce stone recurrence and severity, but supporting evidence is limited.

Patients and Methods

Nephrolithiasis outcomes and 24-h urine data for patients from the Registry for Stones of the Kidney and Ureter (ReSKU), a registry of nephrolithiasis patients collected between 2015 and 2020, were retrospectively analysed. Outcome was stone events, either an office visit where a patient reports symptomatic passage of stones or surgery for stone removal.

Results

We identified 450 stone patients with 24-h urine and kidney stone outcome data. There was no significant difference in 24-h voided volume between patients with one stone event and patients with two or more stone events. On multivariable logistic regression, after controlling for age, gender, BMI, and 24-h sodium and creatinine per kilogram, no significant associations were found between voided volume and stone events. There was a statistically significant negative correlation noted between voided volume and stone events in calcium oxalate dihydrate stone formers (Spearman R = -0.42, p = 0.04), but not others.

Conclusions

Twenty-four-hour voided volume was not associated with stone events in a large institutional cohort, and subset analysis reveals that some stone formers may benefit more from increased voided volume than others; identifying such patients represents a novel precision medicine opportunity.

Comparison of the Effect of Hydroalcholic Extract of Alhagi maurorum and Hydrochlorothiazide on Excretion of 4-10 mm Kidney and Ureteral Stones in Adults: A Randomized Prospective Study

Objective

The prevalence of kidney stones and their complications is high. The review of the literature showed the therapeutic effects of Alhagi maurorum extract on urinary tract stones. This study reviewed the Alhagi plant's hydroalcholic extract's effect on eliminating kidney and ureteral stones compared to hydrochlorothiazide.

Materials and Methods

In this randomized prospective study, from March 2019 to September 2021, 80 patients over 18 years of age with kidney stones in the upper ureter with a size of 4-10 mm were divided into two groups based on the block random allocation method. The first group received hydrochlorothiazide tablets (50 mg), and the second group received 1 gram/day of the hydroalcholic areal extract of Alhagi maurorum in a two-divided capsule. The mean size and number of stones, renal function tests, and side effects were checked and compared in both groups before and after the study.

Results

Mean age, sex, serum urea level (P=0.351), serum creatinine (P=0.393), stone size (P=0178), and the number of stones (P=0.052) before intervention were similar. After intervention, the size and number of stones diminished, up to 70% in both groups. However, there was not a statistically significant difference between the two groups.

Conclusion

The study showed that Alhagi maurorum is as effective as hydrochlorothiazide in treatment of kidney and ureteral stones with no significant complications and is promising.