Annual Incidence of Nephrolithiasis among Children and Adults in South Carolina from 1997 to 2012

Association between kidney stones and poor sleep factors in U.S. adults

The purpose of our study is to examine the correlation between sleep factors and the prevalence of kidney stones in US adults. A total of 34,679 participants from the National Health and Nutrition Examination Survey 2007 to 2018 were included in the analyses. Sleep data collection included: presleep factors (difficulty falling asleep, sleep onset latency), intra-sleep factors (risk index of obstructive sleep apnea, restless leg syndrome, difficulty maintaining sleep), post-sleep factors (daytime sleepiness, non-restorative sleep), sleep schedule and duration, and sleep quality. Logistic regression models were used to analyze the correlation between sleep factors and the prevalence of kidney stones. Among the 34,679 participants, the overall incidence of kidney stones was 9.3%. The presence of presleep factors (difficulty falling asleep [odds ratios [OR], 1.680; 95% CI, 1.310-2.150], prolonged sleep onset latency [OR, 1.320; 95% CI, 1.020-1.700]), intra-sleep factors (higher risk index of obstructive sleep apnea [OR, 1.750; 95% CI, 1.500-2.050], restless leg syndrome [OR, 1.520; 95% CI, 1.150-1.990], difficulty maintaining sleep [OR, 1.430; 95% CI, 1.130-1.810]), post-sleep factors (daytime sleepiness [OR, 1.430; 95% CI, 1.220-1.680], non-restorative sleep [OR, 1.400; 95% CI, 1.110-1.760]), short sleep duration (OR, 1.190; 95% CI, 1.080-1.310), mediate sleep quality (OR, 1.140; 95% CI, 1.020-1.290), and poor sleep quality (OR, 1.500; 95% CI, 1.310-1.720) are linked to the occurrence of kidney stones. However, short sleep onset latency, bedtime and wake-up time were not significantly associated with the prevalence of kidney stones. These findings showed positive associations between higher kidney stone prevalence and poor sleep factors.

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.

Bacteria-mediated resistance of neutrophil extracellular traps to enzymatic degradation drives the formation of dental calculi

Dental calculi can cause gingival bleeding and periodontitis, yet the mechanism underlying the formation of such mineral build-ups, and in particular the role of the local microenvironment, are unclear. Here we show that the formation of dental calculi involves bacteria in local mature biofilms converting the DNA in neutrophil extracellular traps (NETs) from being degradable by the enzyme DNase I to being degradation resistant, promoting the nucleation and growth of apatite. DNase I inhibited NET-induced mineralization in vitro and ex vivo, yet plasma DNases were ineffective at inhibiting ectopic mineralization in the oral cavity in rodents. The topical application of the DNA-intercalating agent chloroquine in rodents fed with a dental calculogenic diet reverted NET DNA to its degradable form, inhibiting the formation of calculi. Our findings may motivate therapeutic strategies for the reduction of the prevalence of the deposition of bacteria-driven calculi in the oral cavity.

The intestinal microbiome of children with initial and recurrent nephrolithiasis: A pilot study and exploratory analysis

INTRODUCTION

Kidney stone disease in children is rising disproportionate to the general population, representing a disease population with a distinct biological mechanism as compared to adults. Factors influencing recurrent kidney stone disease in children are poorly characterized and the associations of the intestinal microbiome within sub-populations of kidney stone formers, however, are not well described. We evaluated a pilot cohort of children with nephrolithiasis comparing patients based on recurrent kidney stone episodes and abnormal 24-h urinary parameters, with dual aims to compare the microbiome signal in children with initial and recurrent nephrolithiasis and to explore additional associations in microbiome composition and diversity within this population.

METHODS

Children aged 6-18 with a history of nephrolithiasis, without an active ureteral calculus or antibiotic exposure within 30 days of study entry were eligible to participate. All participants had a 24-h urine study within 6 months of study entry and provided a fecal sample. Microbiome samples were analyzed using 16S ribosomal DNA sequencing techniques for alpha and beta diversity comparing initial and recurrent stone formers as well as microbiome multivariate association (MaAsLin2) to determine differentially abundant taxa. Shotgun sequencing reads were aligned to custom oxidase degradation and butyrate production gene databases (5 databases total). Comparisons for MaAsLin2 and shotgun metagenomics, normalized to sequencing depth, were based on stone recurrence, sex, hypercalcuria (≤4 mg/kg/day), hyperoxaluria (≥45 mg/1.73 m2), and hypocitraturia (<310 mg/1.73 m2 [females] or < 365 mg/1.73 m2 [males]).

RESULTS

A total of 16 enrolled children provided samples sufficient for analyses, including 9 girls and 7 boys, of whom 5 had experienced recurrent kidney stone events. Three participants had hypercalcuria, 2 had hyperoxaluria, and 4 had hypocitraturia. Comparisons of Formyl-CoA transferase between index and recurrent urinary stone disease revealed a trend towards higher mean abundance of the gene in initial stone formers (0.166% vs 0.0343%, p = 0.2847) (Summary Figure), while trends toward lower biodiversity were also noted in the recurrent stone cohort on both Faith (p = 0.06) and Shannon (p = 0.05) indices. Exploratory analyses found Eubacterium siraeum to be significantly greater in relative abundance in children with documented hypercalciuria (p = 0.001).

DISCUSSION

Our pilot study demonstrates possible signals in both microbial diversity and oxalate gene expression, both of which are lower in recurrent pediatric kidney stone patients. These findings warrant further investigation as a potential diagnostic marker for future kidney stone events.

Endoscopic combined intrarenal surgery composed of micro-perc and retrograde intrarenal surgery in the treatment of complex kidney stones in children

OBJECTIVE

This research aims to explore the efficiency and safety of endoscopic combined intrarenal surgery (Micro-ECIRS) composed of micro-percutaneous nephrolithotomy (Micro-perc) and retrograde intrarenal surgery (RIRS) in the Galdakao-modified supine Valdivia (GMSV) position for a single session for the treatment of complex nephrolithiasis in children.

MATERIALS AND METHODS

This study retrospectively reviewed patients aged < 18 years who underwent Micro-ECIRS in the GMSV position for renal stones larger than 2 cm under ultrasound guidance between August 2020 to May 2022 at our institution.

RESULTS

A total of 13 patients (8 males and 5 females) received Micro-ECIRS for renal stones under ultrasound guidancewhile adopting the GMSV position. The average stone size was 2.7 cm (range: 2.1-3.7 cm). Among them, 6 patients had left kidney stones, 5 patients had right kidney stones, and 2 patients had bilateral kidney stones. The mean operative time was 70.5 min (range: 54-93 min). The mean hospital stay was 6.4 days (range: 4-9 days). The mean hemoglobin decrease was 8.2 g/L (range: 5.1-12.4 g/L). The total number of kidneys that had complete stone clearance was 8 kidneys at 48 h postoperatively, 11 kidneys at 2 weeks postoperatively, and 14 kidneys at 1 month postoperatively.

CONCLUSION

Our results demonstrate that Micro-ECIRS while patients are in the GMSV position is a safe and effective method for the treatment of complex children nephrolithiasis. However, all children made three hospital visits and received anesthesia three times. Further research is needed to confirm these findings.

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.

Climate change and kidney stones

PURPOSE OF REVIEW

Kidney stones affect an increasing proportion of the population. We suggest that these trends are in part influenced by exposure to higher temperatures as a result of climate change and urbanization. The changing epidemiology of kidney stones is a topic worthy of discussion due to the economic and healthcare burden the condition poses as well as the quality-of-life disruption faced by individuals with kidney stones.

RECENT FINDINGS

The relationship between heat and kidney stones is well supported. Exposure to high temperatures has been shown to increase risk for stone development within a short time frame. Effects are modified by factors such as sex, comorbid conditions, and population vulnerability and adaptability. Urban heat islands (UHIs) likely exaggerate the effect of increasing global surface temperature. The concentration of UHIs often coincides with historic redlining practices in the United States, potentially contributing to observed disparities in kidney health among minoritized populations. As global surface temperature increases and urbanization trends continue, a greater proportion of the world's population is exposed to significant temperature extremes each year, leading to the expectation that kidney stone prevalence will continue to increase.

SUMMARY

This work describes the effect of increasing global surface temperature as a result of climate change on kidney stone disease and kidney health. These effects may result in further perpetuation of significant kidney stone related social disparities. We suggest strategies to mitigate the effects of heat exposure on stone formation.

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.

Multi-site microbiota alteration is a hallmark of kidney stone formation

BACKGROUND

Inquiry of microbiota involvement in kidney stone disease (KSD) has largely focussed on potential oxalate handling abilities by gut bacteria and the increased association with antibiotic exposure. By systematically comparing the gut, urinary, and oral microbiota of 83 stone formers (SF) and 30 healthy controls (HC), we provide a unified assessment of the bacterial contribution to KSD.

RESULTS

Amplicon and shotgun metagenomic sequencing approaches were consistent in identifying multi-site microbiota disturbances in SF relative to HC. Biomarker taxa, reduced taxonomic and functional diversity, functional replacement of core bioenergetic pathways with virulence-associated gene markers, and community network collapse defined SF, but differences between cohorts did not extend to oxalate metabolism.

CONCLUSIONS

We conclude that multi-site microbiota alteration is a hallmark of SF, and KSD treatment should consider microbial functional restoration and the avoidance of aberrant modulators such as poor diet and antibiotics where applicable to prevent stone recurrence. Video Abstract.

Current Status of Protein Biomarkers in Urolithiasis-A Review of the Recent Literature

Urolithiasis is an increasingly common clinical problem worldwide. The formation of stones is a combination of metabolic status, environmental factors, family history and many other aspects. It is important to find new ways to quickly detect and assess urolithiasis because it causes sudden, severe pain and often comes back. One way to do this is by exploring new biomarkers. Current advances in proteomic studies provide a great opportunity for breakthroughs in this field. This study focuses on protein biomarkers and their connection to kidney damage and inflammation during urolithiasis.

In focus: perplexing increase of urinary stone disease in children, adolescent and young adult women and its economic impact

Background

Urinary stone disease (USD) historically has affected older men, but studies suggest recent increases in women, leading to a near identical sex incidence ratio. USD incidence has doubled every 10 years, with disproportionate increases amongst children, adolescent, and young adult (AYA) women. USD stone composition in women is frequently apatite (calcium phosphate), which forms in a higher urine pH, low urinary citrate, and an abundance of urinary uric acid, while men produce more calcium oxalate stones. The reasons for this epidemiological trend are unknown.

Methods

This perspective presents the extent of USD with data from a Canadian Province and a North American institution, explanations for these findings and offers potential solutions to decrease this trend. We describe the economic impact of USD.

Findings

There was a significant increase of 46% in overall surgical interventions for USD in Ontario. The incidence rose from 47.0/100,000 in 2002 to 68.7/100,000 population in 2016. In a single United States institution, the overall USD annual unique patient count rose from 10,612 to 17,706 from 2015 to 2019, and the proportion of women with USD was much higher than expected. In the 10-17-year-old patients, 50.1% were girls; with 57.5% in the 18-34 age group and 53.6% in the 35-44 age group. The roles of obesity, diet, hormones, environmental factors, infections, and antibiotics, as well as the economic impact, are discussed.

Interpretation

We confirm the significant increase in USD among women. We offer potential explanations for this sex disparity, including microbiological and pathophysiological aspects. We also outline innovative solutions - that may require steps beyond typical preventive and treatment recommendations.

Associations of exposure to heavy metal mixtures with kidney stone among U.S. adults: A cross-sectional study

Assessing the effects of heavy metals (HMs) on kidney stone is often limited to analyzing individual metal exposures, with studies on the effects of exposure to mixtures of HMs being scarce. To comprehensively evaluate the relationship between exposure to mixed HMs and kidney stones, we analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 2007-2016, which included 7809 adults. We used multiple statistical methods, including multiple logistic regression models, weighted quantile sum (WQS) regression, quantile g-computation (qgcomp) and bayesian kernel machine regression (BKMR), to assess the association between single HM and mixed exposure to HMs and kidney stones. Firstly, in single exposure analysis, urinary cadmium (Cd) and cobalt (Co) demonstrated a positive association with the risk of kidney stones. Secondly, various other approaches consistently revealed that mixed exposure to HMs exhibited a positive association with kidney stone risk, primarily driven by Cd, Co, and barium (Ba) in urine, with these associations being particularly notable among the elderly population. Finally, both BKMR and survey-weighted generalized linear models consistently demonstrated a significant synergistic effect between urinary Co and urinary uranium (Ur) in elevating the risk of kidney stones. Overall, this study provides new epidemiological evidence that mixed exposure to HMs is associated with an increased risk of kidney stones. Further prospectively designed studies are needed to confirm these findings.

Pediatric Stone Disease: Current Trends and Future Directions

Pediatric nephrolithiasis is less common in children than in adults but the incidence has been rising rapidly, and it is now a public health and economic burden in the United States. There are challenges unique to children that should be taken into consideration when evaluating and managing pediatric stone disease. In this review, we present the current research on risk factors, emerging new technologies for treatment of stones and recent investigations on prevention of stones in this population.

Machine Learning Models to Predict Kidney Stone Recurrence Using 24 Hour Urine Testing and Electronic Health Record-Derived Features

Objective

To assess the accuracy of machine learning models in predicting kidney stone recurrence using variables extracted from the electronic health record (EHR).

Methods

We trained three separate machine learning (ML) models (least absolute shrinkage and selection operator regression [LASSO], random forest [RF], and gradient boosted decision tree [XGBoost] to predict 2-year and 5-year symptomatic kidney stone recurrence from electronic health-record (EHR) derived features and 24H urine data (n = 1231). ML models were compared to logistic regression [LR]. A manual, retrospective review was performed to evaluate for a symptomatic stone event, defined as pain, acute kidney injury or recurrent infections attributed to a kidney stone identified in the clinic or the emergency department, or for any stone requiring surgical treatment. We evaluated performance using area under the receiver operating curve (AUC-ROC) and identified important features for each model.

Results

The 2- and 5- year symptomatic stone recurrence rates were 25% and 31%, respectively. The LASSO model performed best for symptomatic stone recurrence prediction (2-yr AUC: 0.62, 5-yr AUC: 0.63). Other models demonstrated modest overall performance at 2- and 5-years: LR (0.585, 0.618), RF (0.570, 0.608), and XGBoost (0.580, 0.621). Patient age was the only feature in the top 5 features of every model. Additionally, the LASSO model prioritized BMI and history of gout for prediction.

Conclusions

Throughout our cohorts, ML models demonstrated comparable results to that of LR, with the LASSO model outperforming all other models. Further model testing should evaluate the utility of 24H urine features in model structure.

Low Potassium Intake: A Common Risk Factor for Nephrolithiasis in Patients with High Blood Pressure

Hypertension (Htn) is a crucial cause of cardio-vascular and chronic kidney disease. Moreover, it is an independent risk factor for nephrolithiasis (NL). A diet rich in vegetables and fruits is indicated for both Htn and NL prevention, and the 24-h urinary potassium excretion can be used as a warning light for adherence. The aim of this study is to demonstrate the association between urinary potassium excretion and recurrent nephrolithiasis among patients affected by Htn. We have analyzed medical records of 119 patients affected by Htn and NL (SF-Hs) referring to Bone and Mineral Metabolism laboratory and 119 patients affected by Htn but without NL (nSF-Hs) referring to Hypertension and Organ Damage Hypertension related laboratory, both in Federico II University of Naples. The potassium 24-h urinary levels in SF-Hs were significantly lower compared to nSF-Hs. This difference was confirmed by the multivariable linear regression analysis in the unadjusted model and adjusted model for age, gender, metabolic syndrome, and body mass index. In conclusion, a higher potassium urinary excretion in 24-h is a protective factor against NL in patients affected by Htn and dietary interventions can be considered for kidney protection.

Pediatric urolithiasis: what can pediatricians expect from radiologists?

The incidence of urolithiasis in children has increased over the two last decades. Urolithiasis formation results from urine oversaturation following insufficient water intake, urinary obstruction (notably in cases of congenital uropathies), excess production of an insoluble compound, or imbalance between crystallization promoters and inhibitors. Whereas most urolithiases in adults occur secondary to environmental factors, in children, secondary causes are far more frequent, and 15% are related to genetic causes, most often monogenic. This is especially true in recurrent forms, with early and rapid progression and bilateral stones, and in cases of familial history or consanguinity. Because of differing clinical management, one should rule out cystinuria, primary hyperoxaluria and renal tubular acidosis, among other causes of urolithiasis. As such, a complete biochemical evaluation must be performed in all cases of pediatric urolithiasis, even in cases of an underlying uropathy. Ultrasound examination is the first-line modality for imaging pediatric urolithiasis, allowing both diagnosis (urolithiasis and its complications) and follow-up. US examination should also explore clues to an underlying cause of urolithiasis. This review is focused on the role of imaging in the management and etiological assessment of pediatric urolithiasis. Radiologists play an important role in pediatric urolithiasis, facilitating diagnosis, follow-up and surgical management. A trio of clinicians (pediatric nephrologist, pediatric surgeon, pediatric radiologist) is thus necessary in the care of these pediatric patients.

Pediatric Nephrolithiasis

The prevalence of pediatric nephrolithiasis has increased dramatically in the past two decades for reasons that have yet to be fully elucidated. Workup of pediatric kidney stones should include metabolic assessment to identify and address any risk factors predisposing patients to recurrent stone formation, and treatment should aim to facilitate stone clearance while minimizing complications, radiation and anesthetic exposure, and other risks. Treatment methods include observation and supportive therapy, medical expulsive therapy, and surgical intervention, with choice of treatment method determined by clinicians' assessments of stone size, location, anatomic factors, comorbidities, other risk factors, and preferences and goals of patients and their families. Much of the current research into nephrolithiasis is restricted to adult populations, and more data are needed to better understand many aspects of the epidemiology and treatment of pediatric kidney stones.

Epidemiology of Kidney Stones

In the past two decades, major breakthroughs that improve our understanding of the pathophysiology and therapy of kidney stones (KS) have been lacking. The disease continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of kidney stones. Our expanding knowledge of the epidemiology of kidney stones is of paramount importance and largely upgrades the modern management of the disease. In this paper, we review the variables affecting prevalence and incidence, including age, gender, race, ethnicity, occupation, climate, geography, systemic diseases, diabetes, vascular disease, chronic kidney disease, and dietary risk factors relevant to kidney stones.

Influence of BMI on the Recurrence Rate of Nephrolithiasis in the Adult Population of Saudi Arabia: A Retrospective Study

Objectives Nephrolithiasis is a common disease, and Saudi Arabia is among the countries with the highest prevalence of nephrolithiasis. Obesity is one of the risk factors associated with the increased formation of renal calculi. We aimed to assess whether obesity also increases the recurrence rate of nephrolithiasis. Methods We retrospectively identified and collected data of 283 adult patients with renal stones who were managed at our hospital from November 2018 to November 2021. The demographic information, comorbidities, stone burden, and treatment methods related to them were identified, collected, and analyzed. Moreover, we performed the chi-squared test (χ2) and multivariate logistic regression analysis in order to assess the risk factors (i.e., independent predictors) of recurrence among the studied patients. Additionally, the odds ratio (OR) was calculated at a confidence interval (CI) of 95%. A p-value of less than 0.05 was considered statistically significant. Results Of the 283 adult patients we analyzed, 35 did not meet the criteria of our study and, consequently, were excluded. Therefore, we ended up with 248 patients, of whom 179 (68.1%) were males, 131 (52.8%) had a previous history of renal stones, and 90 (36.3%) had chronic illnesses. Moreover, the mean age of the studied patients was 48.91 ± 14.51 years, and the mean BMI was 29.44 ± 6.1 kg/m². It was found that most of the patients (35.5%) had only one stone, while 23.4% of them had more than 5 stones. Furthermore, the majority of the stones (35.9%) were medium size (with a stone diameter of 10-19 mm [1-1.9 cm]). We did not find a relationship between obesity and the recurrence rate of renal stones. However, there was a significant association (p < 0.05) between the recurrence rate and Saudi nationality, chronic diseases (more specifically, HTN), unilateral stones, and a stone diameter of 10-19 mm (1-1.9 cm). Additionally, we identified diabetes and the kidney as stone location factors that are associated with less recurrence. Conclusion Although obesity was reported to increase the risk of renal stone formation, we did not find it to be associated with an increased recurrent rate of the disease in the Saudi Arabian population, which is inconsistent with other studies conducted in this area in other countries. Therefore, larger studies are needed to prove this finding.

Homozygous GRHPR C.494G>A mutation is deleterious that causes early onset of nephrolithiasis in West Bengal, India

Pediatric nephrolithiasis (NL) or Kidney stone disease (KSD) is an untethered topic in Asian population. In Western countries, the annual incidence of paediatric NL is around 6-10%. Here, we present data from West Bengal, India, on lower age (LA, 0-20 years) NL and its prevalence for the first time. To discover the mutations associated with KSD, twenty-four (18 + 6) rare LA-NL patients were selected for Whole Exome Sequencing (WES) and Sanger sequencing, respectively. It was found that GRHPR c. 494G>A mutation (MZ826703) is predominant in our study cohort. This specific homozygous mutation is functionally studied for the first time directly from human peripheral mononuclear cell (PBMC) samples. Using expression study with biochemical activity and computational analysis we assumed that the mutation is pathogenic with loss of function. Moreover, three genes, AGXT, HOGA1 and GRHPR with Novel variants known to cause hyperoxaluria were found frequently in the study cohort. Our study analyses the genes and variations that cause LA-NL, as well as the molecular function of the GRHPR mutation, which may serve as a clinical marker in the population of West Bengal, Eastern India.

Diagnosis and Management of Nephrolithiasis in Children

The incidence of kidney stones in children is increasing. Approximately two-thirds of pediatric cases have a predisposing cause. Children with recurrent kidney stones have an increased higher risk of developing chronic kidney. A complete metabolic workup should be performed. Ultrasound examination is the initial imaging modality recommended for all children with suspected nephrolithiasis. A general dietary recommendation includes high fluid consumption, dietary salt restriction, and increased intake of vegetables and fruits. Depending on size and location of the stone, surgical intervention may be necessary. Multidisciplinary management is key to successful treatment and prevention.

Variation in care between pediatric and adult patients presenting with nephrolithiasis to tertiary care pediatric emergency departments in the United States (2009-2020)

BACKGROUND

Individuals with nephrolithiasis frequently present to the Emergency Department (ED). Safety and quality principles are often applied in pediatric EDs to children presenting with nephrolithiasis, such as limiting ionizing radiation exposure and opioid analgesics. However, it is unknown whether pediatric EDs apply these same principles to adult patients who present with nephrolithiasis. We hypothesized that adult patients would be associated with higher use of radiation-based imaging and opioid analgesics.

OBJECTIVE

To assess variations in diagnostic and treatment interventions and hospital utilization between pediatric and adult patients presenting to the pediatric ED with nephrolithiasis.

STUDY DESIGN

A retrospective cohort study was conducted, examining outcomes for pediatric (<18-years-old) versus adult (≥18-years-old) patients in 42 pediatric EDs from 2009 to 2020 using the Pediatric Health Information System (PHIS) database. Patients with an ICD-9/10 principal diagnosis code of nephrolithiasis with no nephrolithiasis-related visits within the prior 6 months were included. Primary outcomes were imaging, medications, and surgical interventions. Secondary outcomes were hospital admissions, 90-day ED revisits, and 90-day readmissions. Generalized linear mixed models with random effects were used to adjust for confounding and clustering.

RESULTS

In total, 16,117 patients with 17,837 encounters were included. Most hospitals were academic (95.2%), and a plurality were located in the South (38.1%). Most patients were <18-years-old (84.4%, median (interquartile range): 15 (12-17)-years-old), female (57.9%), and White (76.3%), and 17.1% were Hispanic/Latino. Most had no complex chronic conditions (89.2%) and no chronic disease per pediatric medical complexity algorithm (51.5%). For the primary outcome, adults, relative to pediatric patients, who presented to the pediatric ED with nephrolithiasis had higher adjusted odds of receiving computerized tomography (CT) scans (Odds Ratio [OR] 1.43 [95% Confidence Interval [CI] 1.29-1.59]) and opioid analgesics (OR 1.45 [95%CI 1.33-1.58]) (Summary Figure). Secondary outcomes showed that adults, relative to pediatric patients, had lower adjusted odds of hospital admissions, 90-day ED revisits, and 90-day readmissions.

DISCUSSION

Our results suggest that certain pediatric safety and quality principles, such as limiting ionizing radiation exposure and opioid analgesic prescriptions, are not being equally applied to pediatric and adult patients who present to pediatric EDs with nephrolithiasis. The mechanism of these findings remains to be elucidated.

CONCLUSIONS

Variations in care for individuals with nephrolithiasis reflect an opportunity for quality improvement in pediatric EDs and inform work exploring optimal care pathways for all patients presenting to the pediatric ED with nephrolithiasis.

Incidence of Emergency Department Presentations of Symptomatic Stone Disease in Pediatric Patients: A Southeastern Study

Background The incidence of nephrolithiasis during childhood has increased significantly over recent decades. Some studies indicate a rapid rise in adolescents, particularly in African American women. This study serves to identify trends in symptomatic pediatric nephrolithiasis presentations to the emergency department (ED) as a result of increasing incidence and to determine associations between demographic variables at our single-site tertiary pediatric hospital in the Southeast United States. Methods After IRB approval, a review of the data provided by the Pediatric Health Information System, a pediatric database that includes clinical and resource utilization data for 51 of the largest children's hospitals in the nation, yielded 644 pediatric occurrences of nephrolithiasis at single-site emergency departments from 2006 to 2020. The percent change and average percent change in three-year intervals were calculated to establish a trend over time. A chi-square test of independence was performed to assess associations between race, gender, and age groups. Results A total of 780 stone occurrences and associated patient demographic data were reviewed for 644 children (364, 56.52% female) with median age of 183 ± 45.11 months (9-397 months). Of the 644 children, 79 (12.3%) were noted to have recurrent symptomatic nephrolithiasis, contributing to 136/780 stone events. There was a marked increase of 84.4% in confirmed pediatric nephrolithiasis occurrences over 15 years, with an average percent increase of 16.1% every three years. A Chi² test of independence was performed between gender and age group (>/< 10yr), gender and race, and race and age group. No expected cell frequencies were less than five. There is no statistically significant relationship between gender and age group, χ² (1, N=644) = 3.30, p=0.692. There is no significant association between race (Caucasian vs. non-Caucasian) and age group (>/< 10yr), χ² (1, N=644) = 0.393, p=0.531. There is a statistically significant relationship between gender and race (Caucasian vs. non-Caucasian), χ² (1, N=644) = 5.28, p=0.021. Caucasian females were more likely to present to our tertiary pediatric hospital's emergency department with nephrolithiasis than Caucasian males or non-Caucasian males or females. Additionally, our data reflected a greater percentage of symptomatic nephrolithiasis presentations occurred in the second decade of life (85.4% vs 14.3%, 552 vs 92 stone events). Conclusion Based on our data, there is a marked increase of 84.4% in pediatric nephrolithiasis occurrences from 2006 to 2020, with a mean increase of 16.1% every three years at our single-site tertiary referral pediatric hospital in the Southeast. Among demographic groups, white adolescent females have an increased risk of developing kidney stones.

Role of Pediatric Ureteral Access Sheath and Outcomes Related to Flexible Ureteroscopy and Laser Stone Fragmentation: A Systematic Review of Literature

Context

Flexible ureteroscopy and laser lithotripsy (FURSL) represent a good treatment option for pediatric urolithiasis. Scarce evidence is available about the safety and efficacy of the concomitant use of a ureteral access sheath (UAS) in the setting of pediatric ureteroscopy (URS).

Objective

To acquire all the available evidence on UAS usage in pediatric FURSL, focusing on intra- and postoperative complications and stone-free rates (SFRs).

Evidence acquisition

We performed a systematic literature research using PubMed/MEDLINE, Embase, and Scopus databases. The inclusion criteria were cohorts of pediatric patients <18 yr old, submitted to URS for FURSL, reporting on more than ten cases of UAS placement. The primary outcomes were prestenting rates, operating time, ureteric stent placement rates after surgery, rates and grades of complications, ureteral injuries, and overall SFR. A total of 22 articles were selected.

Evidence synthesis

In total, 26 intraoperative and 130 postoperative complications following URS with UAS placement were reported (1.8% and 9.18% of the overall procedures, respectively). According to the Clavien-Dindo classification, 32 were classified as Clavien I, 29 as Clavien II, 43 as Clavien I or II, six as Clavien III, and one as Clavien IV. Twenty-one cases of ureteral injuries (1.59%) were noted in the whole cohort; most of them were ureteral perforation or extravasation, and were treated with a temporary indwelling ureteric stent. The overall SFR after a single URS procedure was 76.92%; after at least a second procedure, it was 84.9%.

Conclusions

FURSL is a safe and effective treatment option for pediatric urolithiasis. UAS use was associated with a low rate of ureteric injuries, mostly treated and resolved with a temporary indwelling ureteric stent.

Patient summary

We performed a systematic literature research on the utilization of a UAS during ureteroscopy for stone treatment in pediatric patients. We assessed the outcomes related to the rates of intra- and postoperative complications and the rates of efficacy of the procedure in the clearance of stones. The evidence shows a low rate and grade of complications associated with UAS placement and good stone-free outcomes. A ureteric injury may occur in 1.6% of cases, but it is usually managed and resolved with a temporary indwelling ureteric stent.

The monetary costs of pediatric upper urinary tract stone disease: Analysis in a contemporary United States cohort

INTRODUCTION

The prevalence of upper urinary tract stone disease (USD) in the United States is rising among both adults and children. Studies on the contemporary economic burden of USD management in the pediatric population are lacking.

OBJECTIVE

To comprehensively analyze the economic impact of USD in a contemporary United States pediatric cohort, and to evaluate drivers of cost.

STUDY DESIGN

A retrospective cohort study of pediatric patients (aged 0-17), diagnosed with USD between 2011 and 2018 were identified from PearlDiver-Mariner, an all-payer claims database containing diagnostic, treatment and prescription data provided in all treatment settings. Relevant International Classification of Disease (ICD-9 and ICD-10) and Current Procedural Terminology (CPT) codes were used for identification, and only patients with claims recorded for at least one year before and after entry of a diagnosis code for USD were selected (N = 10,045). Patients were stratified into those undergoing operative vs. non-operative management and for each patient, total 1-year healthcare costs following USD diagnosis, including same day and non-same day encounters, were analyzed. Factors associated with increased spending, as well as economic trends were analyzed.

RESULTS

Overall, 8498 (85%) patients were managed non-operatively, while 1547 (15%) underwent a total of 1880 procedural interventions. Total overall cost was $117.1 million, while median annual expenditure was $15.8 million. Proportion of spending for outpatient, inpatient and prescription services was 52%, 32% and 16%, respectively (Table). Outpatient management accounted for 67% of overall spending. The proportion of patients managed non-operatively increased significantly over time, in parallel with spending for non-operative care. Comorbidity burden, treatment year and geographic region were among predictors of costs.

DISCUSSION

Our study is the first to report actual insurance reimbursements for pediatric USD management using actual reimbursement data, examined across all treatment settings. We found that majority of the costs were for outpatient services and for non-operative management, with a rising tendency toward non-operative management over time. Regional variation in expenditures was evident. Specific reasons underlying these observed patterns could not directly be discerned from our dataset, but merit further investigation.

CONCLUSION

Non-operative and outpatient management for pediatric USD are increasingly common, resulting in parallel shifts in spending. Notably, 52% of overall spending was for outpatient care. These insights into the contemporary economic burden of pediatric USD could provide value in shaping future healthcare policy.

Comparative effectiveness of paediatric kidney stone surgery (the PKIDS trial): study protocol for a patient-centred pragmatic clinical trial

INTRODUCTION

The strength of the evidence base for the comparative effectiveness of three common surgical modalities for paediatric nephrolithiasis (ureteroscopy, shockwave lithotripsy and percutaneous nephrolithotomy) and its relevance to patients and caregivers are insufficient. We describe the methods and rationale for the Pediatric KIDney Stone (PKIDS) Care Improvement Network Trial with the aim to compare effectiveness of surgical modalities in paediatric nephrolithiasis based on stone clearance and lived patient experiences. This protocol serves as a patient-centred alternative to randomised controlled trials for interventions where clinical equipoise is lacking.

METHODS AND ANALYSIS

The PKIDS is a collaborative learning organisation composed of 26 hospitals that is conducting a prospective pragmatic clinical trial comparing the effectiveness of ureteroscopy, shockwave lithotripsy and percutaneous nephrolithotomy for youth aged 8-21 years with kidney and/or ureteral stones. Embedded within clinical care, the PKIDS trial will collect granular patient-level, surgeon-level and institution-level data, with a goal enrolment of 1290 participants over a 21-month period. The primary study outcome is stone clearance, defined as absence of a residual calculus of >4 mm on postoperative ultrasound. Secondary outcomes include patient-reported physical, emotional and social health outcomes (primarily using the Patient-Reported Outcome Measurement Information System), analgesic use and healthcare resource use. Timing and content of secondary outcomes assessments were set based on feedback from patient partners. Heterogeneity of treatment effect for stone clearance and patient-reported outcomes by participant and stone characteristics will be assessed.

ETHICS AND DISSEMINATION

This study is approved by the central institutional review board with reliance across participating sites. Participating stakeholders will review results and contribute to development dissemination at regional, national and international meetings.

TRIAL REGISTRATION NUMBER

NCT04285658; Pre-results.

The genetics of kidney stone disease and nephrocalcinosis

Kidney stones (also known as urinary stones or nephrolithiasis) are highly prevalent, affecting approximately 10% of adults worldwide, and the incidence of stone disease is increasing. Kidney stone formation results from an imbalance of inhibitors and promoters of crystallization, and calcium-containing calculi account for over 80% of stones. In most patients, the underlying aetiology is thought to be multifactorial, with environmental, dietary, hormonal and genetic components. The advent of high-throughput sequencing techniques has enabled a monogenic cause of kidney stones to be identified in up to 30% of children and 10% of adults who form stones, with ~35 different genes implicated. In addition, genome-wide association studies have implicated a series of genes involved in renal tubular handling of lithogenic substrates and of inhibitors of crystallization in stone disease in the general population. Such findings will likely lead to the identification of additional treatment targets involving underlying enzymatic or protein defects, including but not limited to those that alter urinary biochemistry.

Pediatric Stone Surgery: What Is Hot and What Is Not

PURPOSE OF REVIEW

We aim to highlight recent advances in technology and techniques for surgical management of urinary tract calculi in pediatric patients.

RECENT FINDINGS

Percutaneous nephrolithotomy (PCNL) is classically performed in the prone position. The supine PCNL was first attempted to overcome the shortcomings of difficult airway access, patient and surgeon discomfort. The supine PCNL, and subsequent modifications, has been successfully described in the pediatric population. Classically, PCNL has also been classically concluded with obligate placement of a nephrostomy tube and bladder catheter. Recently, tubeless and totally tubeless PCNL reduces pain and duration of hospitalization with satisfactory surgical outcomes in children. Finally, we describe the use of thulium laser technology, which offers improved efficacy in stone treatment and may supplant the current dominant technologies in coming years. Recent advances in pediatric stone surgery include supine PCNL, miniaturized PCNL instrumentation, tubeless procedures, and thulium laser technology.

Risk factors for subsequent stone events in pediatric nephrolithiasis: A multi-institutional analysis

INTRODUCTION

Children with nephrolithiasis have a 50% risk of recurrence 3 years following an index urinary stone event. The American Urological Association guidelines for medical management of nephrolithiasis suggest metabolic evaluations be stratified according to risk of future stone events. However, no such risk stratification exists across the pediatric population with urinary stone disease. We aim to assess the risk factors among pediatric patients for a subsequent stone event (SSE).

MATERIALS AND METHODS

A retrospective review for children <17 years of age with a diagnosis of nephrolithiasis and at least one completed follow-up at two tertiary-care children's hospitals within our state between 2012 and 2017 was performed. Children with known monogenic stone disease were excluded as well as those with follow-up less than 1 year. SSEs following initial diagnosis and treatment for nephrolithiasis were defined as follows: subsequent surgical intervention, new stone on imaging, reported stone passage, or ED evaluation for renal colic. Clinical and demographic factors were compared between patients with and without SSEs and analyzed using univariate and multivariate analyses via Cox proportional hazard models. Survival curves for significant associations for SSEs were generated and evaluated using Log-Rank and Wilcoxon comparisons.

RESULTS

A total of 200 patients with median clinical follow-up of 2.9 years were analyzed. Median age was 11.5 years (IQR: 6.0-15.5), with 109 (54.5%) males and 91 (45.5%) females, 94 (47%) of whom had a relevant comorbidity. An SSE occurred in 82 patients (41.0%). Age >12 (HR 2.21, 95%CI 1.42-3.45), reported stone event prior to enrollment encounter (i.e. personal history of nephrolithiasis) (HR 1.82, 95%CI 1.14-2.89), and family history of nephrolithiasis (HR 1.62, 95%CI 1.05-2.51) were associated with SSE on univariate analysis while age >12 (HR 2.09, 95%CI 1.33-3.27) and personal history of nephrolithiasis (HR 1.63, 1.02-2.6) retained significance on multivariable analysis. Survival analysis shows increased risk of recurrence with accumulation of risk factors (Summary Figure). Sensitivity analysis accounting for missing family history data retained significance for all three variables.

CONCLUSIONS

Adolescent age and a personal history of nephrolithiasis are independent risk factors for SSE in children. Understanding these risk factors and the nature of SSE among the pediatric population can potentially enhance counseling for further metabolic work-up and tailored clinical follow-up.

The impact of heat on kidney stone presentations in South Carolina under two climate change scenarios

The risk of kidney stone presentations increases after hot days, likely due to greater insensible water losses resulting in more concentrated urine and altered urinary flow. It is thus expected that higher temperatures from climate change will increase the global prevalence of kidney stones if no adaptation measures are put in place. This study aims to quantify the impact of heat on kidney stone presentations through 2089, using South Carolina as a model state. We used a time series analysis of historical kidney stone presentations (1997–2014) and distributed lag non-linear models to estimate the temperature dependence of kidney stone presentations, and then quantified the projected impact of climate change on future heat-related kidney stone presentations using daily projections of wet-bulb temperatures to 2089, assuming no adaptation or demographic changes. Two climate change models were considered—one assuming aggressive reduction in greenhouse gas emissions (RCP 4.5) and one representing uninibited greenhouse gas emissions (RCP 8.5). The estimated total statewide kidney stone presentations attributable to heat are projected to increase by 2.2% in RCP 4.5 and 3.9% in RCP 8.5 by 2085–89 (vs. 2010–2014), with an associated total excess cost of ~ $57 million and ~ $99 million, respectively.

Urinary manifestations in African American and Caucasian inflammatory bowel disease patients: a retrospective cohort study

Background

Inflammatory bowel diseases (IBD), like ulcerative colitis (UC) and Crohn’s disease (CD), are associated with urinary extra-intestinal manifestations, like urolithiasis and uncomplicated urinary tract infections (UTIs). The literature reviewed for this study identifies an increased association of CD and urolithiasis against the general population as well as UC. Furthermore, the rates in which urinary comorbidities manifest have not been well characterized in cross-race analyses. The purpose of this study is to establish the prevalence of common urinary extra-intestinal manifestations in CD and UC and to further determine at what rate these affect the African American and Caucasian populations.

Methodology

This is a retrospective cohort study using de-identified data collected from a research data base that included 6 integrated facilities associated with one tertiary healthcare center from 2012 to 2019. The electronic chart records for 3104 Caucasian and African American IBD patients were reviewed for frequency of urolithiasis and uncomplicated UTI via diagnosed ICD-10 codes. Comparison between data groups was made using multivariate regressions, t-tests, and chi square tests.

Results

Our study included 3104 patients of which 59% were female, 38% were African American, and 43% were diagnosed with UC. Similar proportions of UC and CD diagnosed patients developed urolithiasis (6.0% vs 6.7%, p = 0.46), as well as uncomplicated UTIs (15.6% vs. 14.9%, p = 0.56). Similar proportions of African American and Caucasian patients developed urolithiasis (5.4% vs 7.0%, p = 0.09), but a higher proportion of African Americans developed uncomplicated UTIs (19.4% vs 12.6%, p ≤ 0.001).

Conclusion

We found similar rates of urolithiasis formation in both UC and CD in this study. Furthermore, these rates were not significantly different between African American and Caucasian IBD populations. This suggests that UC patients have an elevated risk of urolithiasis formation as those patients with CD. Additionally, African Americans with IBD have a higher frequency of uncomplicated UTI as compared to their Caucasian counterparts.

Composition of urinary stones in children: clinical and metabolic determinants in a French tertiary care center

As the epidemiology of urolithiasis is constantly evolving, analyzing the composition of stones is crucial to better understand the determinants of lithogenesis. The aim of this study was to describe the composition of stones of pediatric patients in a tertiary center. Clinical and metabolic data from all pediatric patients with at least one stone that was analyzed by Fourier transformed infrared spectroscopy (FTIR) in the Hospices Civils de Lyon between 2013 and 2017 were retrospectively collected. A total of 111 patients (sex ratio 1.4:1) were included; their median ([IQR]) age was 7.5 (3.1-10.5) years. The main component of stones was calcium oxalate (weddellite for 34 (31%) stones, whewellite 23 (21%)), calcium phosphate (carbapatite 32 (29%), brushite 6 (5%), amorphous calcium phosphate 3 (3%)), struvite 5 (5%), cystine 4 (4%), uric acid 2 (2%), and ammonium acid urate 2 (2%). A total of 20 (18%) stones were pure and 24 (22%) were infectious. Carbapatite stones were the most frequent in patients < 2 years and calcium oxalate stones in patients > 2 years old. Metabolic abnormalities (most frequently hypercalciuria) were found in 50% of tested patients and in 54% of patients with infectious stones. Congenital anomalies of the kidney and/or urinary tract (CAKUT) or neurogenic bladder were present in 9/24 (38%) patients with infectious stones and 12/16 (76%) patients with bladder stones.Conclusion: This study confirms that calcium oxalate stones are the most frequent among pediatric patients, which could reflect the nutritional habits of predisposed patients. In contrast, infectious stones are less frequent and occur mostly in association with anatomic or metabolic favoring factors.

Association of Urine Findings with Metabolic Syndrome Traits in a Population of Patients with Nephrolithiasis

Background

The odds of nephrolithiasis increase with more metabolic syndrome (MetS) traits. We evaluated associations of metabolic and dietary factors from urine studies and stone composition with MetS traits in a large cohort of stone-forming patients.

Methods

Patients >18 years old who were evaluated for stones with 24-hour urine collections between July 2009 and December 2018 had their records reviewed retrospectively. Patient factors, laboratory values, and diagnoses were identified within 6 months of urine collection and stone composition within 1 year. Four groups with none, one, two, and three or four MetS traits (hypertension, obesity, dyslipidemia, and diabetes) were evaluated. Trends across groups were tested using linear contrasts in analysis of variance and analysis of covariance.

Results

A total of 1473 patients met the inclusion criteria (835 with stone composition). MetS groups were 684 with no traits, 425 with one trait, 211 with two traits, and 153 with three or four traits. There were no differences among groups for urine volume, calcium, or ammonium excretion. There was a significant trend (P<0.001) for more MetS traits being associated with decreasing urine pH, increasing age, calculated dietary protein, urine uric acid (UA), oxalate, citrate, titratable acid phosphate, net acid excretion, and UA supersaturation. The ratio of ammonium to net acid excretion did not differ among the groups. After adjustment for protein intake, the fall in urine pH remained strong, while the upward trend in acid excretion was lost. Calcium oxalate stones were most common, but there was a trend for more UA (P<0.001) and fewer calcium phosphate (P=0.09) and calcium oxalate stones (P=0.01) with more MetS traits.

Conclusions

Stone-forming patients with MetS have a defined pattern of metabolic and dietary risk factors that contribute to an increased risk of stone formation, including higher acid excretion, largely the result of greater protein intake, and lower urine pH.

Sequencing the CaSR locus in Pakistani stone formers reveals a novel loss-of-function variant atypically associated with nephrolithiasis

BACKGROUND

Nephrolithiasis (NL) affects 1 in 11 individuals worldwide and causes significant morbidity and cost. Common variants in the calcium sensing receptor gene (CaSR) have been associated with NL. Rare inactivating CaSR variants classically cause hyperparathyroidism, hypercalcemia and hypocalciuria. However, NL and familial hypercalciuria have been paradoxically associated with select inactivating CaSR variants in three kindreds from Europe and Australia.

METHODS

To discover novel NL-associated CaSR variants from a geographically distinct cohort, 57 Pakistani families presenting with pediatric onset NL were recruited. The CaSR locus was analyzed by directed or exome sequencing.

RESULTS

We detected a heterozygous and likely pathogenic splice variant (GRCh37 Chr3:122000958A>G; GRCh38 Chr3:12228211A>G; NM_000388:c.1609-2A>G) in CaSR in one family with recurrent calcium oxalate stones. This variant would be predicted to cause exon skipping and premature termination (p.Val537Metfs*49). Moreover, a splice variant of unknown significance in an alternative CaSR transcript (GRCh37 Chr3:122000929G>C; GRCh38 Chr3:122282082G >C NM_000388:c.1609-31G >C NM_001178065:c.1609-1G >C) was identified in two additional families.

CONCLUSIONS

Sequencing of the CaSR locus in Pakistani stone formers reveals a novel loss-of-function variant, expanding the connection between the CaSR locus and nephrolithiasis.

Beyond kidney stones: Why pediatricians should worry about hypercalciuria

The incidence of urolithiasis (UL) is increasing, and it has become more common in children and adolescents over the past few decades. Hypercalciuria is the leading metabolic risk factor of pediatric UL, and it has high morbidity, with or without lithiasis as hematuria and impairment of bone mass. The reduction in bone mineral density has already been described in pediatric idiopathic hypercalciuria (IH), and the precise mechanisms of bone loss or failure to achieve adequate bone mass gain remain unknown. A current understanding is that hypercalciuria throughout life can be considered a risk of change in bone structure and low bone mass throughout life. However, it is still not entirely known whether hypercalciuria throughout life can compromise the quality of the mass. The peak bone mass is achieved by late adolescence, peaking at the end of the second decade of life. This accumulation should occur without interference in order to achieve the peak of optimal bone mass. The bone mass acquired during childhood and adolescence is a major determinant of adult bone health, and its accumulation should occur without interference. This raises the critical question of whether adult osteoporosis and the risk of fractures are initiated during childhood. Pediatricians should be aware of this pediatric problem and investigate their patients. They should have the knowledge and ability to diagnose and initially manage patients with IH, with or without UL.

Gender Differences in Kidney Stone Disease (KSD): Findings from a Systematic Review

Purpose of Review

The prevalence of kidney stones is rising and historically carries a preponderance for males. However, recent evidence has questioned whether this gender gap is closing. The aim of this systematic review was to examine this further as well as evaluate possible underlying causes.

Recent Findings

Recent evidence confirms the disparity in kidney stone disease between genders is closing. In the modern era, the rise in prevalence among females has been greater, especially in adolescence. Quality of life is also more adversely affected by kidney stone events among females who are also more likely to develop sepsis after endourological surgery. Males, however, are more likely to present with stone events during periods of high ambient temperatures

Summary

Recent literature demonstrates a temporal change in the disease burden of KSD among men and women. The latter, especially adolescent females, are more likely to develop KSD in their lifetime compared to previous eras. Determining causation is complex and continued research is warranted.

Postoperative outcomes of ureteroscopy for pediatric urolithiasis: A secondary analysis of the National Surgical Quality Improvement Program Pediatric

INTRODUCTION

Incidence of pediatric urinary stone disease (PUSD) has increased over recent decades. Innovations in ureteroscopic technology has expanded the role of endourologic stone management in children. However, there is currently no consensus on the optimal use of ureteroscopy (URS) within the heterogenous PUSD population.

OBJECTIVE

The primary objective was to investigate the rate of 30-day unplanned readmissions in pediatric patients after URS. The secondary objective was to examine the influence of demographic, perioperative, postoperative, and reoperation variables as predictors of an increased risk of unplanned readmission in this sample.

STUDY DESIGN

A secondary analysis was performed on retrospectively collected data from the National Surgical Quality Improvement Program Pediatric between 2015 and 2018. Pediatric patients diagnosed with PUSD and treated with URS were identified. Patients undergoing concurrent or additional surgeries during the URS procedure were excluded. Data on demographic, perioperative, postoperative, and unplanned reoperation variables were examined for their possible influence on 30-day unplanned readmissions. Descriptive statistics were used to characterize the study cohort. Continuous and categorical variables were analyzed using independent samples t-test, one-way ANOVA with Tukey post-hoc test, and Chi-square Tests or Fisher's Exact Test, respectfully. Multivariate analysis was performed using stepwise logistic regression.

RESULTS

A total of 2510 patients were identified within the study period. The majority of children undergoing URS were between 12 and 18 years of age (66.1%), female (56.9%), and had renal calculi (45.2%). Of these, 162 (6.5%) experienced a 30-day unplanned readmission related to the URS procedure. The most common reasons for an unplanned readmission was urinary tract infection (31.4%), new/unresolved stone (28.3%), and postoperative pain (8.2%). Multivariate modelling showed that females (Relative Risk [RR]: 2.03; 95% Confidence Interval [95%CI]: 1.34-3.07), patients with renal stones (RR: 1.77; 95%CI: 1.10-2.83), and inpatients at the time of surgery (RR: 1.61; 95%CI: 1.03-2.51) were more at risk of an unplanned readmission within 30-days of an URS procedure.

CONCLUSION

This study reports on short-term unplanned readmission rates in pediatric patients who underwent an URS procedure. Further it highlights possible predictors of unplanned readmission rates within a sampling of patients from NSQIP affiliated institutions. The findings from this study can be used to guide future studies around the safe use of URS in pediatric patients.

Disparities in Kidney Stone Disease: A Scoping Review

PURPOSE

We reviewed the available evidence regarding health disparities in kidney stone disease to identify knowledge gaps in this area.

MATERIALS AND METHODS

A literature search was conducted using PubMed®, Embase® and Scopus® limited to articles published in English from 1971 to 2020. Articles were selected based on their relevance to disparities in kidney stone disease among adults in the United States.

RESULTS

Several large epidemiological studies suggest disproportionate increases in incidence and prevalence of kidney stone disease among women as well as Black and Hispanic individuals in the United States, whereas other studies of comparable size do not report racial and ethnic demographics. Numerous articles describe disparities in imaging utilization, metabolic workup completion, analgesia, surgical intervention, stone burden at presentation, surgical complications, followup, and quality of life based on race, ethnicity, socioeconomic status and place of residence. Differences in urinary parameters based on race, ethnicity and socioeconomic status may be explained by both dietary and physiological factors. All articles assessed had substantial risk of selection bias and confounding.

CONCLUSIONS

Health disparities are present in many aspects of kidney stone disease. Further research should focus not only on characterization of these disparities but also on interventions to reduce or eliminate them.

The current status of preventive measures for urinary calculi in children

Urological calculus is a common disease in urology. Urological calculi are generally more common in adults but have become more common in children in recent years. Most existing studies focus on the prevention of urinary calculi in adults; there are relatively few articles on calculi in children. Reported preventive measures are not comprehensive enough, while the latest research progress has not been updated. The pathogenesis and preventive measures associated with urinary calculi have been the focus of research, but many preventive measures still need further clarification. This article reviews the progress on preventive measures for urinary calculi in children.

Effect of antibiotic treatment on Oxalobacter formigenes colonization of the gut microbiome and urinary oxalate excretion

The incidence of kidney stones is increasing in the US population. Oxalate, a major factor for stone formation, is degraded by gut bacteria reducing its intestinal absorption. Intestinal O. formigenes colonization has been associated with a lower risk for recurrent kidney stones in humans. In the current study, we used a clinical trial of the eradication of Helicobacter pylori to assess the effects of an antibiotic course on O. formigenes colonization, urine electrolytes, and the composition of the intestinal microbiome. Of 69 healthy adult subjects recruited, 19 received antibiotics for H. pylori eradication, while 46 were followed as controls. Serial fecal samples were examined for O. formigenes presence and microbiota characteristics. Urine, collected serially fasting and following a standard meal, was tested for oxalate and electrolyte concentrations. O. formigenes prevalence was 50%. Colonization was significantly and persistently suppressed in antibiotic-exposed subjects but remained stable in controls. Urinary pH increased after antibiotics, but urinary oxalate did not differ between the control and treatment groups. In subjects not on antibiotics, the O. formigenes-positive samples had higher alpha-diversity and significantly differed in Beta-diversity from the O. formigenes-negative samples. Specific taxa varied in abundance in relation to urinary oxalate levels. These studies identified significant antibiotic effects on O. formigenes colonization and urinary electrolytes and showed that overall microbiome structure differed in subjects according to O. formigenes presence. Identifying a consortium of bacterial taxa associated with urinary oxalate may provide clues for the primary prevention of kidney stones in healthy adults.

Meta-analysis of Clinical Microbiome Studies in Urolithiasis Reveal Age, Stone Composition, and Study Location as the Predominant Factors in Urolithiasis-Associated Microbiome Composition

To determine whether functionally relevant questions associated with the urinary or gut microbiome and urinary stone disease (USD) can be answered from metagenome-wide association studies (MWAS), we performed the most comprehensive meta-analysis of published clinical MWAS in USD to date, using publicly available data published prior to April 2021. Six relevant studies met inclusion criteria. For alpha-diversity, significant differences were noted between USD status, stone composition, sample type, study location, age, diet, and sex. For beta-diversity, significant differences were noted by USD status, stone composition, sample type, study location, antibiotic use (30 days and 12 months before sampling), sex, hypertension, water intake, body habitus, and age. Prevotella and Lactobacillus in the gut and urinary tract, respectively, were associated with healthy individuals, while Enterobacteriaceae was associated with USD in the urine and stones. Paradoxically, other Prevotella strains were also strongly associated with USD in the gut microbiome. When data were analyzed together, USD status, stone composition, age group, and study location were the predominant factors associated with microbiome composition. Meta-analysis showed significant microbiome differences based on USD status, stone composition, age group or study location. However, analyses were limited by a lack of public data from published studies, metadata collected, and differing study protocols. Results highlight the need for field-specific standardization of experimental protocols in terms of sample collection procedures and the anatomical niches to assess, as well as in defining clinically relevant metadata and subphenotypes such as stone composition.

Incidence of nephrolithiasis after bladder augmentation in people with spina bifida

INTRODUCTION

Risks of nephrolithiasis after bladder augmentation in people with spina bifida (SB) remain unclear. Annual incidence of nephrolithiasis in the general population is 0.01% for 10-14 years old, 0.07% for 15-19 years old and 0.2% for 20-24 years old. Our aim was to assess the incidence and risk factors of nephrolithiasis in SB patients after augmentation.

METHODS

Patients with SB and augmentation followed at our institution were retrospectively reviewed (born ≥1972, surgery 1979-2019). Patients were screened annually with renal bladder ultrasound and abdominal radiograph. Main outcome was nephrolithiasis treatment. Kaplan-Meier survival and Cox proportional hazards analysis were used. Possible predictors were assessed using stepwise forward selection (variables with p < 0.1 on univariate analysis included in multivariate analysis).

RESULTS

427 patients with SB and augmentation were included (51.8% female, 74.9% shunted). Median age at augmentation was 8.5 years (median follow-up: 12.4 years, ileum segment: 81.0%, bladder neck procedure: 60.7%, urinary channel: 74.2%) and 28.8% developed bladder stones. Overall, 47 (11.0%) patients were treated for nephrolithiasis. After correction for differential follow-up, nephrolithiasis was treated in 7.3% at 10 years, 13.2% at 15 years, and 18.0% at 20 years (Figure). Patients presented with either a urinary tract infection (46.8%), on screening (44.7%), or pain (8.5%). Stones were treated percutaneously, endoscopically or by ESWL (63.8%/34.0%/10.7%, respectively). Most were calcium stones (58.3%). On multivariate analysis, compared to younger patients, patients augmented at ≥10 years of age had 1.84 times the risk of nephrolithiasis (p = 0.01). Nephrolithiasis was more common in those who developed bladder stones (HR = 3.00, p < 0.0001). Among those with both renal and bladder stones, bladder stones typically preceded nephrolithiasis (55.2%), were treated concurrently (31.0%) and 13.8% occurred after nephrolithiasis. Gender, wheelchair use, bowel segment used, MACE and skeletal fractures were not associated with higher nephrolithiasis risk (p ≥ 0.11).

DISCUSSION

This study of a large cohort of SB patients with long-term follow-up highlights that the risk of nephrolithiasis is cumulative and related to bladder stone formation, age at augmentation and time since augmentation. An association with bladder stones suggests potential shared metabolic causes. The study's retrospective design likely led to underestimating the risk of nephrolithiasis by not capturing spontaneously passed stones.

CONCLUSION

Approximately 1% of patients with SB develop nephrolithiasis annually after augmentation. Close long-term surveillance after augmentation is strongly indicated, as nephrolithiasis incidence in augmented patient with SB is at least 10 times higher than general population. Patients with bladder stones are especially at risk.

Effect of age, BMI, and gender on urinary risk factors in pediatric idiopathic stone formers

INTRODUCTION

The incidence of pediatric urolithiasis has been increasing over the years; however, the etiology of this increase is not well understood. Age, body mass index, and gender have been examined as possible risk factors for stone disease, but with inconsistent and variable associations.

OBJECTIVE

We aim to investigate the urine chemistry factors, as assessed by 24-h urinary parameters, in pediatric stone formers at a large volume tertiary referral center in the highest areas in the United States, the Southeast, based on age, body mass index, and gender.

STUDY DESIGN

We retrospectively reviewed all pediatric stone formers who completed a 24-h study between 2005 and 2016. Patients were stratified by age (3-10 versus 11-18 years of age), overweight status (above versus below the 85th percentile for body mass index), and gender (male versus female) (Summary Figure). Statistical analysis included analysis of variance and logistic regression.

RESULTS

243 patients were included in our analysis. Patients in the first decade of life were found to have greater numbers of urinary risk factors than those in the second decade. Non-overweight patients were more likely to have hyperoxaluria and hyperuricosuria, while overweight patients were more likely to have hypocitraturia. Female patients were more likely to have higher hyperoxaluria, while male patients were more likely to have hypercalciuria.

DISCUSSION

In contrast to prior publications, obesity is not linked to increased risk of urolithiasis with non-overweight individuals having a greater number of risk factors than the overweight cohort. Despite stone disease being more prevalent in adolescents, the greatest number of risk factors were present in the first decade of life. Lastly, female children had more urinary risk factors than males. Further understanding of the underlying causes of stone disease in various pediatric populations is warranted.

CONCLUSION

While more urinary risk factors were identified in younger, non-overweight, and female patients, there remains no consensus on the urinary risk factors for pediatric urolithiasis. Further study is needed to elucidate the risk factors and pathophysiology of pediatric stone disease.

Outcome of Mini-Percutaneous Nephrolithotomy in Patients Under the Age of 18: An Experience With 112 Cases

Purpose: Renal calculi are becoming more common among children. Although, extracorporeal shock wave lithotripsy (ESWL) is the first choice in this age group, minimal invasive surgeries, such as percutaneous nephrolithotomy (PCNL), are indicated for some patients. Recently, PCNL devices have become smaller in size with acceptable efficacy and lower complications. We evaluated the outcomes and complications of mini-PCNL (MPCNL) surgery in our referral training centers.

Materials and Methods: Between September 2012 and January 2020, a total of 112 children under the age of 18, who had shown failure of ESWL, and/or their parents refused to do it, underwent MPCNL (15 Fr). The patients' profiles were reviewed for data collection including preoperative and stone data, operation information, and postoperative complications.

Results: Of 112 patients, 69 were boys, and 43 were girls. Their mean age was 8.6 years (14 months to 18 years). Mean stone size was 20 mm (14–34 mm). Seventy-four cases had renal pelvic stone, 22 had pelvis and lower pole, and 16 had staghorn. The mean operation time was 65 min (35–100 min), and mean radiation time was 0.6 min (0.2–1.4 min). Low-grade fever was detected in 14 patients (12.5%). Four patients needed blood transfusion and two had increased creatinine, which improved with conservative management. One patient developed urosepsis that resolved with antibiotic therapy. None of the patients had kidney perforation or other organ injury or death. Early stone-free rate (SFR) after operation was 90.2% (101 patients). Six patients had residual fragment <5 mm, which passed spontaneously in 2 weeks after operation (total SFR 95.3%). Three patients underwent second-look nephroscopy, and ureteroscopy was done for two patients due to migrated stone fragments to the distal ureter.

Conclusion: MPCNL is recommended as a safe alternative option for treatment of the nephrolithiasis in children with good outcome and acceptable complications.

Ureterolithiasis in Adolescents: A Case Report

A 13-year-old patient presented to the emergency department with a history of abdominal pain and right flank pain. Two days before, she was evaluated at her pediatrician's office and was diagnosed with acute gastroenteritis and sent home. In the emergency department, the patient was diagnosed with ureterolithiasis after a physical examination, laboratory work, and imaging findings. She was treated successfully with conservative medical management. Symptomatic presentation of ureterolithiasis can include abdominal pain, flank pain, hematuria, dysuria, urgency, nausea, and vomiting. Nurse practitioners need to recognize nonspecific symptoms of ureterolithiasis for accurate diagnosis and treatment. Risk factors, signs and symptoms, prevention, and treatment options for ureterolithiasis are discussed.

Standardization of microbiome studies for urolithiasis: an international consensus agreement

Numerous metagenome-wide association studies (MWAS) for urolithiasis have been published, leading to the discovery of potential interactions between the microbiome and urolithiasis. However, questions remain about the reproducibility, applicability and physiological relevance of these data owing to discrepancies in experimental technique and a lack of standardization in the field. One barrier to interpreting MWAS is that experimental biases can be introduced at every step of the experimental pipeline, including sample collection, preservation, storage, processing, sequencing, data analysis and validation. Thus, the introduction of standardized protocols that maintain the flexibility to achieve study-specific objectives is urgently required. To address this need, the first international consortium for microbiome in urinary stone disease - MICROCOSM - was created and consensus panel members were asked to participate in a consensus meeting to develop standardized protocols for microbiome studies if they had published an MWAS on urolithiasis. Study-specific protocols were revised until a consensus was reached. This consensus group generated standardized protocols, which are publicly available via a secure online server, for each step in the typical clinical microbiome-urolithiasis study pipeline. This standardization creates the benchmark for future studies to facilitate consistent interpretation of results and, collectively, to lead to effective interventions to prevent the onset of urolithiasis, and will also be useful for investigators interested in microbiome research in other urological diseases.

Risk of Symptomatic Kidney Stones During and After Pregnancy

RATIONALE & OBJECTIVE

There are several well-known anatomical and physiological changes during pregnancy that could contribute to kidney stone formation, but evidence that they increase the risk of kidney stones during pregnancy is lacking. We determined whether there was an increased risk of a first-time symptomatic kidney stone during and after pregnancy.

STUDY DESIGN

A population-based matched case-control study.

SETTING & PARTICIPANTS

945 female first-time symptomatic kidney stone formers aged 15-45 years and 1,890 age-matched female controls in Olmsted County, MN, from 1984-2012. The index date was the date of onset of a symptomatic kidney stone for both the case and her matched controls.

EXPOSURE

The primary exposure was pregnancy with assessment for variation in risk across different time intervals before, during, and after pregnancy. Medical records were manually reviewed to determine the conception and delivery dates for pregnancies.

OUTCOME

Medical record-validated first-time symptomatic kidney stone.

ANALYTICAL APPROACH

Conditional and unconditional multivariable logistic regression analysis.

RESULTS

Compared with nonpregnant women, the odds of a symptomatic kidney stone forming in women was similar in the first trimester (OR, 0.92; P=0.8), began to increase during the second trimester (OR, 2.00; P=0.007), further increased during the third trimester (OR, 2.69; P=0.001), peaked at 0 to 3 months after delivery (OR, 3.53; P<0.001), and returned to baseline by 1year after delivery. These associations persisted after adjustment for age and race or for diabetes mellitus, hypertension, and obesity. These results did not significantly differ by age, race, time period, or number of prior pregnancies. Having a prior pregnancy (delivery date>1year ago) was also associated with a first-time symptomatic kidney stone (OR, 1.27; P=0.01).

LIMITATIONS

Observational study design in a predominantly White population. The exact timing of stone formation cannot be determined.

CONCLUSIONS

Pregnancy increases the risk of a first-time symptomatic kidney stone. This risk peaks close to delivery and then improves by 1 year after delivery, though a modest risk of a kidney stone still exists beyond 1 year after delivery.