Urolithiasis in pediatric patients

Urinary stone in infants; should vitamin D prophylaxis be stopped?

BACKGROUND

This study investigated the effect of the discontinuation of vitamin D supplementation on kidney stone formation in children under 2 years of age.

METHODS

This study involved a retrospective analysis of two patient groups. The first group comprised postoperative patients who were stone-free, while the second group consisted of asymptomatic patients with kidney stones. The patients who discontinued vitamin D supplementation and those who continued were compared in terms of stone formation and stone size progression. The data collected included patient characteristics, stone size measurements, and laboratory results.

RESULTS

The findings showed that the discontinuation of vitamin D supplementation was not associated with kidney stone formation or the progression of stone size in either group. For patients who were stone-free on ultrasonography 1 month after the operation, according to the 12-month ultrasonography evaluation, in the group that discontinued vitamin D, 42 (78%) patients had no stones, 6 (11%) patients had stones larger than 3 mm, and 6 (11%) patients had microlithiasis. However, in the group that continued vitamin D, 49 (72%) patients were stone-free, 10 (15%) patients had stones larger than 3 mm, and 9 (13%) patients had microlithiasis. There was no difference between the groups in terms of stone status at 12 months (p = 0.76). For patients with asymptomatic kidney stones, the initial stone sizes were similar between the groups (p = 0.74). During the 6th month of ultrasound, the changes in stone size were 1.76 ± 1.81 mm and 1.79 ± 1.75 mm for the two groups, respectively (p = 0.9). During the 12-month ultrasound measurement, the changes in stone size were 1.98 ± 2.93 mm and 2.60 ± 2.48 mm for the two groups, respectively (p = 0.09).

CONCLUSIONS

We believe that more research is needed to make definitive recommendations regarding vitamin D prophylaxis in infants with kidney stones. Although the first objective of our study is not conclusively proven with the current findings, we recommend continued vitamin D prophylaxis in infants with urolithiasis.

Metabolic Evaluation and Recurrence Prevention for Urinary Stone Patients: An EAU Guidelines Update

BACKGROUND AND OBJECTIVE

The aim of this review was to define patients who are at high risk of recurrence of urolithiasis, to delineate diagnostic and therapeutic algorithms for each type of stone, and to clarify general guidelines and recommendations for prevention of recurrence.

METHODS

A professional research librarian carried out literature searches for all sections of the urolithiasis guidelines, covering the timeframe between 1976 and June 2023.

KEY FINDINGS AND LIMITATIONS

For every patient with urolithiasis, an attempt should be made to analyse the stone. Patients should be given general instructions on how to prevent recurrence, including adequate fluid and calcium intake, and low consumption of sodium and protein. Identifying and correcting the causative factors is a cornerstone in preventing the recurrence of urolithiasis. Diagnostic and therapeutic algorithms by stone composition are available. Every patient should undergo baseline metabolic screening, while patients with calcium stones, who are at high risk of relapse and complications, should undergo extensive metabolic screening with two 24-h urine collections and should receive targeted therapy. Patients with uric acid, infection, or cystine stones are at high risk of relapse. All patients at high risk of recurrence should be closely monitored, especially those not complying with therapy in the long term.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Metabolic stone evaluation and patient follow-up are highly recommended to prevent urolithiasis recurrence.

PATIENT SUMMARY

We reviewed the evidence for proper evaluation of patients with urinary and stones and the treatment options for preventing stone recurrence. It is essential to determine the type of stone and to carry out specific blood and urine tests for planning the best treatment course for each patient.

Risk factors for recurrence in pediatric urinary stone disease

BACKGROUND

Children's urinary system stones may develop from environmental, metabolic, anatomical, and other causes. Our objective is to determine the recurrence and prognosis, demographic, clinical, and etiological characteristics of children with urolithiasis.

METHODS

Medical records of patients were evaluated retrospectively. Patients' demographic data and medical history, serum/urine biochemical and metabolic analysis, blood gas analysis, stone analysis, imaging findings, and medical/surgical treatments were recorded.

RESULTS

The study included 364 patients (male 187). Median age at diagnosis was 2.83 (IQR 0.83-8.08) years. The most common complaints were urinary tract infection (23%) and urine discoloration (12%). Sixty-two percent had a family history of stone disease. At least one metabolic disorder was found in 120 (88%) of 137 patients having all metabolic analyses: hypercalciuria was found in 45%, hypocitraturia in 39%, and hyperoxaluria in 37%. Anatomical abnormalities were detected in 18% of patients. Of 58 stones analyzed, 65.5% were calcium and 20.6% were cystine stones. Stone recurrence rate was 15% (55/364). Older age (> 5 years), family history of stone disease, stone size (≥ 5 mm), and urinary system anatomical abnormalities were significantly associated with stone recurrence (p = 0.027, p = 0.031, p < 0.001, and p < 0.001, respectively). In adjusted logistic regression analysis, stone size ≥ 5 mm (OR 4.85, 95% CI 2.53-9.3), presence of urinary system anatomical abnormalities (OR 2.89, 95% CI 1.44-5.78), and family history of stone disease (OR 2.41, 95% CI 1.19-4.86) had increased recurrence rate.

CONCLUSIONS

All children with urolithiasis should be evaluated for factors affecting stone recurrence. Children at higher risk of recurrence need to be followed carefully.

Current Status and Prospects of Pediatric Stone Disease: A Bibliometric and Visualization Study

Pediatric stone disease, once considered rare, has emerged as a significant research area in the past two decades due to a sharp increase in its incidence. Understanding the evolving epidemiology and treatment strategies for pediatric stone disease is crucial for enhancing child health protection. This study aims to summarize the advancements in pediatric stone disease research over the last two decades through bibliometric analysis. We conducted a comprehensive search in the Web of Science Core Collection (WoSCC) for literature on pediatric stone disease from January 1, 2000 to February 20, 2024. Econometric analyses were performed using tools such as VOSviewer, CiteSpace, and the R package "bibliometrix." Our search yielded 1,208 publications, predominantly from the United States and Turkey, showing an annual increase in publications on pediatric stone disease. Leading research institutions include Dicle University, Children's Hospital of Philadelphia, and the University of Pennsylvania, with the Journal of Pediatric Urology publishing the highest number of articles. The most prolific authors were C.P. Nelson and B. Hoppe, with Caleb P. Nelson being the most co-cited author. Research themes primarily focused on risk factors and therapeutic approaches for pediatric stone disease. Emerging research hotspots are identified by keywords such as mechanism, mini-percutaneous nephrolithotomy, recurrence, and retrograde intrarenal surgery. The study forecasts a continued upward trend in global research on pediatric stone disease, with future studies likely to delve deeper into risk factors and novel therapeutic methods.

Paediatric Renal Stone Management in Africa: A Scoping Review and Analysis of Current Practices

Renal stones are solid deposits formed from minerals and salts that develop within the kidneys and urinary tract. While the condition is more common among adults, children and even infants can also be affected. There is an increasing incidence of paediatric renal stones in Africa alongside multiple challenges faced in managing the condition. This scoping review aimed to provide an overview of the management modalities of paediatric renal stones in Africa. This study utilised Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist. A systematic search was conducted in three electronic databases: PubMed, African Journal Online (AJOL), and Google Scholar, with 1,180 articles curated. After extensive examination, 10 articles satisfied the inclusion criteria. The review found that calcium oxalate stones were the most prevalent type, accounting for 34.03% of cases, followed by whewellite stones and ammonium urate stones. The most frequent location for stones was the kidney, and the most common symptom was pain. Abdominopelvic ultrasound was the most frequently utilised investigation. Of the 886 patients managed for renal stones, 75.4% were managed surgically, 2.9% medically, and 21.7% spontaneously resolved without intervention. This review identifies opportunities for improving the management of paediatric renal stones in Africa, including the need for standardised diagnostic and treatment protocols and the development of evidence-based guidelines tailored to the African context. Overall, this scoping review provides valuable insights into the patterns and management of paediatric renal stones in Africa and highlights the need for further research to improve the management of this condition in the region.

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.

Urolithiasis in children; The importance of stone localization in treatment and follow-up

To evaluate the demographic, etiologic, treatment, and follow-up differences in stones according to their location within the kidney. This retrospective study comprised 337 patients with urolithiasis between 2015 and 2019. Patients were classified into 2 groups according to stone location as lower pole stones (LPS) and upper-middle pole stones (UMPS). The patient's data were recorded at 3-month intervals for one year. One hundred and eighty-three (54.3%) female and 154 (45.7%) men were included in the study. One hundred and twenty-nine (38.3%) of the stones were in the LPS and 208 (61.7%) in the UMPS. UMPS was more common in patients aged > 12 months (p < 0.01). At least one metabolic risk factor was present in 93 (72.1%) patients with LPS and 164 (78.4%) with UMPS. The most common urinary metabolic risk factors were hyperoxaluria (31.8%) in patients with LPS and hypocitraturia (34.1%) in patients with UMPS. ROC analysis results showed that cut-off values of 5.5 mm for LPS and 6.1 mm for UMPS did not provide improve with medical treatment. At the 6- and 12-month follow-ups, the improvement rates were higher in the UMPS group than in the LPS group (p < 0.05). During the follow-up, recurrence was detected in 43 patients: 29% of patients with LPS and 5.8% of patients with UMPS (p < 0.01). Patients with small stones can be followed up. Surgical treatment may be considered for small stones in the LPS. In addition, the risk of recurrence is higher in patients with LPS, and close follow-up is required.

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.

Management of Pediatric Urolithiasis in an Italian Tertiary Referral Center: A Retrospective Analysis

Background and Objectives: In recent years, the prevalence of pediatric urolithiasis has increased in North America and Western countries, though it is endemic in developing countries. The aim of this study is to describe the experience of a tertiary pediatric referral center in the surgical management of pediatric urolithiasis. Materials and Methods: We retrospectively reviewed the experience of patients ≤ 16 years old affected by urinary stones who underwent surgery. Results: From April 2021 to September 2023, 31 pediatric patients underwent surgical procedures for stone diseases at our department: 13 preschool-aged (1-5 years) and 18 school-aged (6-16 years) children. During this period, 12 URSs, 17 RIRSs, and 2 PCNLs were recorded. Five patients had residual fragments at first, so three of them underwent a second endourological lithotripsy (2 RIRSs and 1 URS). Complete clearance was finally achieved in 27 patients. The stone composition was evaluated in 25 cases. Conclusions: Numerous innovations in the surgical treatment of pediatric urolithiasis have resulted from the development of smaller devices and new technology. Our results show how, in experienced centers, retrograde and percutaneous lithotripsy are safe and effective procedures for use in pediatric populations.

Population genetics analysis of SLC3A1 and SLC7A9 revealed the etiology of cystine stone may be more than what our current genetic knowledge can explain

BACKGROUND

Cystine stone is a Mendelian genetic disease caused by SLC3A1 or SLC7A9. In this study, we aimed to estimate the genetic prevalence of cystine stones and compare it with the clinical prevalence to better understand the disease etiology.

METHODS

We analyzed genetic variants in the general population using the 1000 Genomes project and the Human Gene Mutation Database to extract all SLC3A1 and SLC7A9 pathogenic variants. All variants procured from both databases were intersected. Pathogenic allele frequency, carrier rate, and affected rate were calculated and estimated based on Hardy-Weinberg equilibrium.

RESULTS

We found that 9 unique SLC3A1 pathogenic variants were carried by 26 people and 5 unique SLC7A9 pathogenic variants were carried by 12 people, all of whom were heterozygote carriers. No homozygote, compoun d heterozygote, or double heterozygote was identified in the 1000 Genome database. Based on the Hardy-Weinberg equilibrium, the calculated genetic prevalence of cystine stone disease is 1 in 30,585.

CONCLUSION

The clinical prevalence of cystine stone has been previously reported as 1 in 7,000, a notably higher figure than the genetic prevalence of 1 in 30,585 calculated in this study. This suggests that the etiology of cystine stone is more complex than what our current genetic knowledge can explain. Possible factors that may contribute to this difference include novel causal genes, undiscovered pathogenic variants, alternative inheritance models, founder effects, epigenetic modifications, environmental factors, or other modifying factors. Further investigation is needed to fully understand the etiology of cystine stone.

Cystine Stones: Developments in Minimally Invasive Surgery and Their Impact on Morbidity and Stone Clearance

Cystinuria is a rare genetic condition that is responsible for cystine stones. Besides stone recurrence, patients with cystine stones have reduced health-related quality of life, increased rates of chronic kidney disease and hypertension. Although lifestyle measures, medical therapy and close follow up are essential to reduce and monitor cystine stone recurrences, surgical intervention is frequently needed for most cystinuria patients. Shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy and active surveillance all have a role, and technological advances in endourology are vital in achieving a stone-free status and to prevent recurrences. The complexity of managing cystine stones necessitates a multidisciplinary team discussion, patient involvement and an individualised approach in a specialist centre for optimum management. Thulium fibre laser and virtual reality may have an increasing role in the future of cystine stone management.

Why is childhood urolithiasis increasing? Etiology, diagnosis and management: a single-center experience

BACKGROUND

Globally, urolithiasis is becoming more and more common among children. We aimed to determine the etiology, and the diagnostic and therapeutic approaches in patients with urolithiasis.

METHODS

This was a retrospective study which included all patients (aged 1 month-18 years) admitted to the pediatric nephrology clinic in Elazığ Fethi Sekin City Hospital with urolithiasis between November 2019 and 2021. Only patients whose diagnosis of urolithiasis was confirmed by urinary ultrasonography were included in the study, while patients with chronic diseases (neurological diseases such as epilepsy, cerebral palsy, chronic bowel diseases, etc.) predisposing to kidney stone formation were not. Demographic characteristics, serum and urine biochemical parameters, urine metabolic and kidney stone metabolic and chemical analyses, urinary tract ultrasonography findings and treatment modalities were collected.

RESULTS

One hundred ninety-seven patients (91 female and 106 male) were included in the study. Hypervitaminosis D was detected in 4 (2%) patients, suppressed parathyroid hormone in 12 (6%) and hypercalcemia in 27 (14%) patients. Metabolic screening showed hypercalciuria in 69 (35%) patients, hypocitraturia in 39 (20%), hyperoxaluria in 15 (8%) and cystinuria in 6 (3%) patients. Eighty three (42%) patients had a positive family history for kidney stones. One hundred eighteen (60%) patients received potassium citrate treatment, 71 (36%) were given hydration and diet recommendations without medical treatment, 6 (3%) received tiopronin treatment, and 2 (1%) patients were treated surgically.

CONCLUSIONS

Our study suggests that Vitamin D supplementation at doses higher than 400 IU/day may be a risk factor for kidney stones in children. We observed that mothers tend not to give water to infants who are breastfed or formula-fed in the first year of life. K-citrate treatment can be a good option for prevention and dissolution of stones by alkalinization.

Dietary supplements and medicinal plants in urolithiasis: diet, prevention, and cure

BACKGROUND

Urolithiasis has been a major health concern for centuries, primarily owing to the limited treatment options in the physician's armamentarium. However, various studies have underscored a lesser incidence of urolithiasis in cohorts predominantly consuming fruits and vegetables. This article aims to review various dietary plants, medicinal herbs and phytochemicals in the prevention and management of urolithiasis.

METHODS

To provide context and evidence, relevant publications were identified on Google Scholar, PubMed and Science-Direct using keywords such as urolithiasis, nephrolithiasis, urolithiasis, renal stones, phytochemicals and dietary plants.

RESULTS

Growing bodies of evidence suggest the incorporation of plant-based foods, medicinal and herbal supplements, and crude drugs containing phytochemicals into the staple diet of people. The anti-urolithiatic activity of these plant bioactives can be attributed to their antioxidant, antispasmodic, diuretic, and inhibitory effect on the crystallization, nucleation and crystal aggregation effects. These mechanisms would help alleviate the events and symptoms that aid in the development and progression of renal calculi. In addition, it will also avoid the exacerbation of secondary disorders like inflammation and injury, which can initiate a vicious circle in turn worsening the disease progression.

CONCLUSION

In conclusion, the results presented in the review demonstrate the promising role of various dietary plants, medicinal and herbal supplements, and phytochemicals in preventing and managing the precipitation of uroliths. However, more conclusive and cogent evidence from preclinical and clinical studies is required to substantiate their safety, efficacy and toxicity profiles in humans.

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.

Antenatal urolithiasis: A case report

INTRODUCTION

Although pediatric urolithiasis is an established entity, its antenatal diagnosis is rare. We hereby report a case detected at 20 weeks gestation and discuss the etiopathogenesis, predisposition, and surveillance following intervention.

CASE REPORT

A 2-year-old girl with left renal pelvic calculus detected antenatally at 20 weeks was evaluated. Left hydronephrosis, obstructive pelvic calculus with a decrease in differential renal function on ethylene dicysteine (EC) renogram was confirmed. The metabolic workup was normal. Following stone extraction by left pyelolithotomy, a left ureteropelvic junction obstruction secondary to a mucosal valve was apparent which was excised and left pyeloplasty was done. Stone analysis revealed 100% cystine. Differential renal function and drainage improved post-surgery. The child, however, did not have a follow-up in the interim and presented with a recurrent stone one and a half years later.

CONCLUSION

Knowledge of antenatal urolithiasis ensures continued follow-up, evaluation for metabolic disorders, and associated structural defects, especially with increasing stone size and increasing hydronephrosis. This helps in timely intervention and continued surveillance.

Meta-Analysis of the Safety and Efficacy of α-Adrenergic Blockers for Pediatric Urolithiasis in the Distal Ureter

OBJECTIVE

Pediatric urolithiasis is a common condition, and medical expulsive therapy has grown to be accepted by many parents. We carried out a meta-analysis to identify the efficacy and safety of α-adrenergic blockers for the treatment of pediatric urolithiasis.

METHODS

We identified related articles from the PubMed, Embase, and Cochrane Library databases. All published randomized controlled trials (RCTs) describing the use of α-adrenergic blockers and placebo treatment for pediatric distal urolithiasis were involved. The outcomes included stone expulsion rate, stone expulsion time, pain episodes, need for analgesia, adverse events, and related subgroup analyses.

RESULTS

A total of nine RCTs were involved in our study, including 586 patients. We found that α-adrenergic blockers could significantly increase the rate of stone expulsion [odds ratio (OR), 3.49; 95% confidence interval (CI), 2.38-5.12; p < 0.00001], reduce the stone expulsion time [mean difference (MD), -5.15; 95% CI, -8.51 to -1.80; p = 0.003], and decrease pain episodes (MD, -1.02; 95% CI, -1.33 to -0.72; p < 0.00001) and analgesia demand (MD, -0.92; 95% CI, -1.32 to -0.53; p < 0.00001) but had a higher incidence of side effects (MD, 2.83; 95% CI, 1.55 to 5.15; p = 0.0007). During subgroup analyses, different medications (tamsulosin, doxazosin, and silodosin) also exhibited better efficiencies than placebo, except for doxazosin, which showed no difference in expulsion time (MD, -1.23; 95% CI, -2.98 to 0.51; p = 0.17). The three kinds of α-adrenergic blockers also appeared to be better tolerated, except for tamsulosin with its greater number of adverse events (MD, 2.85; 95% CI, 1.34 to 6.03; p = 0.006). Silodosin led to a better expulsion rate than tamsulosin (OR, 0.42; 95% CI, 0.20 to 0.92; p = 0.03). In addition, α-adrenergic blockers increased the stone expulsion rate regardless of stone size and decreased the expulsion time of stones measuring <5 mm (MD, -1.71; 95% CI, -2.91 to -0.52; p = 0.005), which was not the case for stones measuring >5 mm in expulsion time (MD, -3.61; 95% CI, -10.17 to 2.96; p = 0.28).

CONCLUSION

Our review suggests that α-adrenergic blockers are well-tolerated and efficient for treating pediatric distal urolithiasis. We also conclude that silodosin is the best choice of drug, offering a better expulsion rate, but it remains to be evaluated further by future studies.

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.

The Impact of Diet on Urinary Risk Factors for Cystine Stone Formation

Despite the importance of dietary management of cystinuria, data on the contribution of diet to urinary risk factors for cystine stone formation are limited. Studies on the physiological effects of diet on urinary cystine and cysteine excretion are lacking. Accordingly, 10 healthy men received three standardized diets for a period of five days each and collected daily 24 h urine. The Western-type diet (WD; 95 g/day protein) corresponded to usual dietary habits, whereas the mixed diet (MD; 65 g/day protein) and lacto-ovo-vegetarian diet (VD; 65 g/day protein) were calculated according to dietary reference intakes. With intake of the VD, urinary cystine and cysteine excretion decreased by 22 and 15%, respectively, compared to the WD, although the differences were not statistically significant. Urine pH was significantly highest on the VD. Regression analysis showed that urinary phosphate was significantly associated with cystine excretion, while urinary sulfate was a predictor of cysteine excretion. Neither urinary cystine nor cysteine excretion was affected by dietary sodium intake. A lacto-ovo-vegetarian diet is particularly suitable for the dietary treatment of cystinuria, since the additional alkali load may reduce the amount of required alkalizing agents.

Prevalence of Vesicoureteral Reflux and Urinary Tract Infection in Children with and without Urolithiasis

Background: Vesicourethral reflux (VUR) is a common urinary tract disorder in children, which may be associated with urolithiasis. Objectives: The current study aimed to investigate vesicoureteral reflux in children with and without urolithiasis. Methods: In this case-control study, 130 children younger than 10 years, with a confirmed diagnosis of urinary tract infection (UTI) are investigated. The demographic information and clinical status of all participants were recorded. Ultrasonography was performed for all children, and they were divided into two groups of 65 subjects based on the results: group 1, children with UTI+stone; and group 2, children with UTI+ non-stone. All children received Voiding Cystourethrogram to evaluate Vesicourethral reflux. Results: The mean age of participants was 7.48 ± 3.2 years, and 68 (52.7%) of them were male. Also, VUR was observed in 33 (25.38%) cases. The frequency of reflux in the UTI + stone group was 21 (32.3%), which was significantly higher than the other group (12 cases, or 18.46%) (P = 0.011). However, the association between UTI and stone (P = 0.3, CC = -0.01) was not significant. Conclusions: This study demonstrated a significant correlation between urinary tract stones and VUR in children with urinary tract infections. It is recommended to investigate the presence of stone or VUR in children suffering from any of the described disorders.

Prevention and management of urinary stone

The prevalence of urolithiasis is increasing not only in South Korea but also around the world. Urolithiasis has a high recurrence rate, therefore, reducing it is very important in the quality of life for stone formers. For this purpose, dietary modifications and drug therapy can be performed through stone analysis and 24-hour urine collection. Stone analysis is recommended for all stone formers, and the 24-hour urine collection is usually recommended for recurrent stone formers or high-risk groups. A general dietary modification for all stone formers includes a sufficient fluid intake, low levels of sodium, sugar, and animal protein, a normal calcium diet, as well as a high amount of citrate intake. Drug therapy should be performed in cases such as the recurrence of stones or increase of the existing ones, even after the application of preservation therapy, such as dietary modification. The ideal drug therapy should prevent the occurrence of urolithiasis, have no side effects, and have a suitable patientsʼ compliance. Follow-up should be performed periodically, through 24-hour urine collections and imaging studies. For follow-up imaging studies, a lowdose non-enhanced computed tomography is recommended, and it can be performed once a year if the patient is in a stable state. To control various and complex metabolic abnormalities in recurrent stone formers, multiple approaches may be required through diet modifications, drug therapy, treatment of the metabolic syndrome, and lifestyle modifications.

Metabolic risk factors in children with kidney stone disease: an update

BACKGROUND

The prevalence of kidney stones in children has significantly increased in the past few decades, with concomitant increased morbidity and healthcare costs worldwide. Assessing metabolic risk factors is essential for diagnosis and specific treatment. The objective of this retrospective study is to identify the epidemiological and clinical characteristics of children under 17 years of age, as well as the metabolic risk factors of nephrolithiasis.

METHODS

A total of 300 children with kidney stone disease were included to undergo several clinical tests using a standardized protocol.

RESULTS

The mean age was 11.2 years, and the male:female ratio was 1.15:1.0. Biochemical abnormalities were found in 89.3% of all cases. A single urine metabolic risk factor was present in 52.6% (n = 141) of the patients, and multiple risk factors were present in 36.7% (n = 106). Idiopathic hypercalciuria (alone or in combination) and hypocitraturia (alone or in combination) were the most frequent risk factors identified in 47.0% and 39.6% of these patients, respectively. Renal colic and/or unspecified abdominal pain were the most frequent forms of presentation (76.9%), followed by hematuria in 64.4% with 97.5% of stones located in the upper urinary tract. A positive family history in first-degree and second-degree relatives was found in 64.8% of boys and 61.8% of girls.

CONCLUSIONS

We conclude that specific urinary metabolic risk factors can be found in most children with kidney stones, with hypercalciuria and hypocitraturia being the most common diagnoses. Graphical abstract .

Nephrolithiasis: Approach to Diagnosis and Management

Although kidney stones are less common in children than in adults, incidence in children is rising. Kidney stones may lead to significant morbidity in addition to escalating medical costs. Clinical presentation is variable. Bilateral kidney stones in a younger child should prompt work-up for primary hyperoxaluria. Metabolic abnormalities are more frequent in children and can result in frequent stone recurrence. Whole exome sequencing data shows genetic defects in about 30% of stone formers. 24 h urine collection should be conducted when patient receives his usual diet and fluid intake with normal activity. Infrared spectroscopy and X-ray diffraction are used for stone analysis. Urine studies should be delayed by 4-6 wk after stone fragmentation or treatment of any stone related complications. The goal of evaluation is to identify modifiable risk factors for which targeted therapy may be instituted. Primary indications for surgical intervention include pain, infection and obstruction. Extracorporeal shockwave lithotripsy (ESWL), ureteroscopy, and percutaneous nephrolithotomy (PCNL) are most commonly used, and selection is based on stone size, anatomy, composition and anatomy. Advances in technology have allowed a shift to minimally invasive surgeries. Comprehensive management requires multidisciplinary team. Children with kidney stones require long term follow-up with periodic assessment of stone forming activity and ascertaining stone burden. High index of suspicion should be there to diagnose diseases like primary hyperoxaluria, Dent's disease, renal tubular acidosis (RTA) etc. as these diseases have ramifications on kidney function and growth.

Risk of chronic kidney disease in patients with kidney stones-a nationwide cohort study

Background

Chronic kidney disease (CKD) and kidney stones are common in Taiwan; in particular, CKD has a high prevalence but low self-awareness rate. CKD-related risk factors such as diabetes, hypertension, and nephrotoxic drugs are well-known and uncontested; however, kidney stones are relatively less studied and easily overlooked as a risk factor. The objective of this study was to investigate whether kidney stones are a risk factor for CKD.

Methods

We conducted a nationwide population-based matched cohort study to assess the risk of incident CKD in people with kidney stones. Data on incident stones formers in the year 2001—excluding those with a history of CKD—were obtained from Taiwan’s National Health Insurance database. Stone formers were matched (1:4) to control subjects according to sex, age, and index date. The total observation period of the study was 10 years, and the primary end-point was the occurrence of CKD. Student’s t-test and Chi-squared test were used to compare continuous and categorical data, respectively. Logistic regression was used to calculate the odds ratio of kidney stone patients with incident CKD relative to the control group. Cox proportional hazard regression model was used to obtain the hazard ratio for development of incident CKD among patients with kidney stones.

Results

The incidence of CKD in the kidney stone cohort was 11.2%, which was significantly higher than that of the control group (P < .001). Survival analysis showed that the stones cohort was 1.82 times more likely to experience CKD than the controls. Age, sex, hypertension, diabetes mellitus, and hyperlipidemia increased the risk of CKD incidence (1.04, 1.27, 1.55, 3.31, and 1.25 times, respectively).

Conclusion

Kidney stones are a definite risk factor for CKD; therefore, patients with stones are suggested to undergo regular renal function monitoring and receive appropriate treatment to avoid CKD.

A single center's experience in pediatric cystine stone disease management: what changed over time?

The authors aimed to evaluate the factors affecting clinical outcomes of cystine stone disease in children and to understand the change in disease management over time. Between January 1991 and September 2017, the demographic and clinical data of pediatric patients with documented cystine stone disease were retrospectively analyzed. Patients with at least 12-month follow-up were included. Disease management and clinical outcomes were compared between the first and second 35 patients managed during the study's time frame. A total of 70 patients were included. The female to male ratio was 30/40. The mean age and follow-up period was 29.8 ± 40.1 months and 106.5 ± 56 months, respectively. The mean initial procedure number to treat the first stone episode was 2.4 ± 1.6. Single stone and single affected site were significant predictors for stone clearance. Overall, patients underwent a mean of 5.5 procedure during their follow-up. Recurrence was detected in 71.4% (50/70) of patients. Residual fragments and non-compliance to medical treatment after the initial intervention were significant predictors for recurrence within shorter interval period. 31.4% (22/70) of patients had renal atrophy during follow-up. They were older at the initial diagnosis and had average urine pH lower than 7.5. The first 35 patients had more open procedures. Still, they had more recurrence rate and tend to have more renal atrophy. As a conclusion, cystine stone disease has a recurrent course in children. Stone and fragments entirely removed (SaFER) concept with all minimally invasive methods available and strict follow-up should be the basis for any management plan.

No stone unturned: The epidemiology and outcomes of paediatric urolithiasis in Manchester, United Kingdom

BACKGROUND

The epidemiology and risk factors for paediatric urolithiasis (UL) in developed countries are evolving, with increasing rates of metabolic stone-formers. In the United Kingdom (UK), only a single London cohort has been studied in the past three decades. Regional disease patterns across the UK remain unknown. UL has been associated with an increased risk of chronic kidney disease in adults, but long-term paediatric outcomes remain poorly understood.

METHODS

We assessed the epidemiology of paediatric UL by defining the demographics, incidence, aetiology, recurrence rates and outcomes at tertiary nephro-urology centres in Greater Manchester. Health records of 177 consecutive paediatric urology referrals (0-18 years) for UL between 2002 and 2015 were retrospectively included for observational analysis. Metabolic screening was performed in 105 children.

RESULTS

The incidence of paediatric urology referrals for UL was 1.77/100,000 person-years, increasing annually by 13.6%. Mean patient age was 8.2 years and the male:female ratio was 1.3:1. The upper urinary tract was involved in more than 90% of cases and 45% of children presented with multiple calculi. Metabolic abnormalities were identified in 52% of children screened: hypercalciuria (64%), hyperoxaluria (18%) and cystinuria (11%) were the most common. Significant family history was predictive of metabolic abnormalities (OR 4.9:1, 95% CI 1.4-17.0). 30% of children had infective stones, which were more common in children less than 6 years. Ultrasound was found to be 90% sensitive for UL detection. Dimercaptosuccinic acid (DMSA) imaging identified renal scarring in 33 of the 55 children tested (60%). Recurrence was observed in 18% of children over mean 6.4 year follow-up and was more common in metabolic stone-formers. Spontaneous passage was observed in 83% of stones ≤ 5 mm, 69% between 5 and 10 mm and only one calculi > 10 mm.

CONCLUSIONS

The incidence of paediatric urology referrals for UL is rising in North West England. Metabolic abnormalities were detected in half of the children tested, justifying comprehensive screening. Recurrence is common following paediatric UL, reinforcing the need for stone prevention strategies. The majority of calculi less than 10 mm were found to pass spontaneously with supportive measures, which favours an initial observation period over surgical intervention for small calculi. UL was associated with renal scarring in the analysed population and therefore, children with UL require long-term assessment of blood pressure and proteinuria.

Management of staghorn stones in special situations

Staghorn stones have always been a challenge for urologists, especially in some special situations, such as horseshoe kidney, ectopic kidney, paediatric kidney, and solitary kidney. The treatment of these staghorn stones must be aggressive because they can lead to renal function loss and serious complications. The gold-standard management for staghorn stones is surgical treatment with the aim of clearing the stones and preserving renal function. Treatment methods for staghorn stones have developed rapidly, such as extracorporeal shock wave lithotripsy, retrograde intrarenal surgery, percutaneous nephrolithotomy and laparoscopy and open surgery. Whether the standard procedures for staghorn stones can also apply to these stones in special situations is still not agreed upon. The decision should be made individually according to the circumstances of the patient. In this review, we evaluates the previous studies and comments on the management of staghorn stones under special situations in the hope of guiding the optimal choice for urologists.

Dietary risk factors for urinary stones in children

PURPOSE OF REVIEW

As the incidence of urinary stone disease in children is increasing, identifying dietary risk factors becomes vitally important, especially in the context of targeting interventions to reduce risk for stone formation. Indiscriminant dietary restrictions are not appropriate for paediatric patients.

RECENT FINDINGS

Although large, prospective studies are still needed to better quantify dietary risk factors for paediatric stone formers, a number of smaller studies provide data to identify common risk factors to help prevent stone formation, while minimizing inappropriate dietary restrictions.

SUMMARY

Interpretation of 24-h urine samples to identify individualized dietary risk factors is crucial for implementing a strategy for prevention of further urinary stone formation in children. Clinicians should avoid generalized dietary restrictions in stone-forming children uninformed by laboratory data.

The effect of additional drug therapy as metaphylaxis in patients with cystinuria: a systematic review

INTRODUCTION

To systematically review the effect of additional drug therapy as metaphylaxis in patients with cystinuria.

EVIDENCE ACQUISITION

A literature search of three databases (MEDLINE, Embase and the Cochrane Library) was performed according to the PRISMA-guidelines enclosing articles published up to May 2019. A total of 1117 articles were screened. Thirty-four publications met the inclusion criteria for this review.

EVIDENCE SYNTHESIS

Male-female ratio in the studied cohorts was 49.9% - 50.1%. The majority of studies showed a positive effect in reducing stone events and/or urinary cystine excretion. D-Penicillamine showed success in 13/14 (92%) studies, whereas Tiopronin-treatment showed a reduction in all (8/8; 100%) studies. All studies on Captopril (4/4) showed a decrease, however not all significant. The same is true for studies on Thiols in combination with Captopril (2/2). Furthermore, Tiopronin showed less side effects compared to D-penicillamine, respectively 30% and 37%. Captopril showed the least adverse events, with one event in nine patients.

CONCLUSIONS

The evidence on benefit of additional drug therapy in patients with cystinuria is scarce. All studied medications showed an effect on stone event and urinary cystine excretion, when used in addition to hyperhydration, alkalization and a diet low on methionine. Based on this systematic review, no drug can be preferred over another. An important aspect in the choice of drug is the risk of side effects. Therefore, the choice of additional drug should be personalized for every patient where the risk of side effects should be taken into consideration.

Amino Acid Transport Defects in Human Inherited Metabolic Disorders

Amino acid transporters play very important roles in nutrient uptake, neurotransmitter recycling, protein synthesis, gene expression, cell redox balance, cell signaling, and regulation of cell volume. With regard to transporters that are closely connected to metabolism, amino acid transporter-associated diseases are linked to metabolic disorders, particularly when they involve different organs, cell types, or cell compartments. To date, 65 different human solute carrier (SLC) families and more than 400 transporter genes have been identified, including 11 that are known to include amino acid transporters. This review intends to summarize and update all the conditions in which a strong association has been found between an amino acid transporter and an inherited metabolic disorder. Many of these inherited disorders have been identified in recent years. In this work, the physiological functions of amino acid transporters will be described by the inherited diseases that arise from transporter impairment. The pathogenesis, clinical phenotype, laboratory findings, diagnosis, genetics, and treatment of these disorders are also briefly described. Appropriate clinical and diagnostic characterization of the underlying molecular defect may give patients the opportunity to avail themselves of appropriate therapeutic options in the future.

Technique, complications, and outcomes of pediatric urolithiasis management at a tertiary care hospital: evolving paradigms over the last 15 years

BACKGROUND

Despite technological advancements, there is lack of consensus for the standard treatment modalities for pediatric urolithiasis.

OBJECTIVE

The primary objective was to review the management of pediatric urolithiasis over the last 15 years in terms of technical modifications, surgical outcomes, and complications. The secondary objective was to compare the efficacy and outcomes of standard percutaneous nephrolithotomy (PCNL) and mini-PCNL for renal and upper ureteric calculi.

STUDY DESIGN

Medical records of all patients aged <18 years who presented to the authors' tertiary care hospital in northern India between August 2003 and December 2018 were reviewed retrospectively. Before 2010, all PCNLs performed were standard PCNL, whereas after 2010, most PCNLs performed were mini-PCNL. Thus, the patients were divided into two groups: group A (patients up to 2010) and group B (patients after 2010). These were compared for the type of treatment, success rate, and complications. The outcomes of surgical management of lower ureteric and vesical calculi were also reviewed.

RESULTS

During this period, there were 580 children with urolithiasis (677 stone sites). There were 265 patients (321 stone sites) in group A and 315 patients (356 stone sites) in group B. The median age was seven years (range: 3-18 years). The most common location of calculus was the collecting system of the kidney (n = 398, 58.8%). A total of 175 stone sites (25.8%) were located in the ureter. Urinary bladder calculi were seen in 43 (6.4%) patients. Multiple stones were seen in 61 sites (9.0%). A total of 115 patients in group A underwent standard PCNL, whereas in group B, nine patients underwent standard PCNL and 129 underwent mini-PCNL. Group B had a significantly higher stone clearance rate for mini-PCNL (P < 0.001). Minor complications (grades 1 and 2) accounted for a majority of overall complications in both groups (87.5% in group A and 94.9% in group B).

DISCUSSION

Mini-PCNL is an excellent option for renal calculi in children as it offers dual advantages of improved stone clearance and reduced major complications such as bleeding. Ureteroscopic lithotripsy has been established as the standard for small lower ureteric calculi.

CONCLUSION

For renal and upper ureteric calculi, mini-PCNL has evolved as standard technique with a high stone-free rate and minimum complications compared with standard PCNL. Extracorporeal shockwave lithotripsy and ureteroscopic lithotripsy (URSL)/retrograde intrarenal surgery are acceptable alternatives for smaller stone burden. For lower ureteric and vesical calculi, retrograde approaches such as cystolithotripsy and URSL have now become the standard of care.

Urolithiasis in children and exposure to melamine: A review of the epidemiological literature

Melamine (ME) is a high production volume compound, mainly used for the synthesis of ME-formaldehyde resins. There is an extensive toxicological and epidemiological database on this compound, but the epidemiology has so far not been reviewed. An extensive literature search in PubMed was conducted and relevant ME epidemiology studies were identified and assessed. The epidemiology data nearly entirely consisted of studies on the health effects due to the food tampering catastrophe in China discovered in 2008 where ME was intentionally added to powdered milk products. Most of these studies were aimed at assessing the extent of the catastrophe and the clinical follow-up of affected children. A reliable dose–response relationship could not be derived from the epidemiology studies. However, they do contain several strong data points that can assist in ranging the No Observed Adverse Effect Level (NOAEL) for humans, for children in particular.

Patient Characteristics Associated With Completion of 24-hour Urine Analyses Among Children and Adolescents With Nephrolithiasis

OBJECTIVE

To inform the development of strategies to improve adherence to guidelines, we sought to identify characteristics of pediatric patients with nephrolithiasis associated with completing 24-hour urine analyses.

MATERIALS AND METHODS

We performed a retrospective cohort study of patients with nephrolithiasis aged 3-18years treated in a large pediatric healthcare system from May 2012 to May 2017. Multivariable Cox models were fit to estimate the association between patient characteristics and completion of a 24-hour urine analysis.

RESULTS

Among 623 patients, 317 (50.9%) completed a 24-hour urine collection. Median age was 14.4years (interquartile range [IQR] 10.5, 16.3). In adjusted analyses, age at diagnosis (hazard ratio [HR] 1.03; 95% confidence interval [CI] 1.01-1.07), renal colic on presentation (HR 1.72; 95% CI 1.15-2.58), and family history of nephrolithiasis (HR 1.50; 95% CI 1.17-1.93) were associated with an increased likelihood of completion of a 24-hour urine. Public/government assistance insurance (HR 0.68; 95% CI 0.48-0.96) was associated with decreased likelihood of completing a 24-hour urine.

CONCLUSION

Patients who had prior painful experiences with stones (renal colic), and potential better understanding of nephrolithiasis (family history, older age on presentation) were more likely to complete a 24-hour urine. Those patients with public insurance/government assistance were less likely to complete a 24-hour urine. These results can be used to develop strategies to improve pediatric patients' adherence to completing 24-hour urine collections.

The effect of selenium supplementation on cystine crystal volume in patients with cystinuria

BACKGROUND

Cystinuria as an autosomal recessive sickness is a relatively rare disease. Formation of cystine stones indicates cystinuria. Few studies are considered the cysteine crystal volume in management of cystinuria. Selenium may inhibit organization of crystal stone, growth and stone aggregation. Since the role of selenium on inhibition of cystine crystal formation is not known, the aim of this study was to evaluate the effect of selenium supplementation on cystine crystals volume in patients with cystinuria.

MATERIALS AND METHODS

This double-blind clinical trial study was conducted on 48 patients in Al-Zahra hospital, Isfahan, Iran from 2015 to 2017. These patients received selenium (200 mg/ daily) for 6 weeks. The urine crystal volume was evaluated before and after treatment. Data were entered SPSS and analyzed by Paired sample T test, Spearman and Pearson coefficient correlation. P- value < 0.05 was considered significant.

RESULTS

In current study, mean cystine crystal volume before and after treatment was 6787.4 ± 11902.6 and 3110.9 ± 7225.4, respectively. Significant difference was observed before and after treatment in terms of cystine crystal volume (p < 0.001). No relation was observed between the mean cystine crystal volume with sex, age and type of medical procedures (p > 0.05).

CONCLUSION

In this study, selenium treatment affected cystine crystal volume. It seems that selenium had the potential value to alleviate the volume of cystine crystal. Therefore, since reducing of cystine crystal volume decreases crystal formation, selenium may be effective to cure patients with cystinuria. However, age, sex and type of medical procedures did not affect cysteine crystal volume.

Incidence of kidney stone disease in Icelandic children and adolescents from 1985 to 2013: results of a nationwide study

BACKGROUND

An increase in the incidence of kidney stone disease has been reported for all age groups worldwide. To examine this trend, we conducted a nationwide study of the epidemiology of kidney stones in Icelandic children and adolescents over a 30-year period.

METHODS

Computerized databases of all major hospitals and medical imaging centers in Iceland were searched for International Classification of Diseases and radiologic and surgical procedure codes indicative of kidney stones in patients aged < 18 years, followed by a thorough medical record review. Age-adjusted incidence was calculated for the time intervals 1985-1989, 1990-1994, 1995-1999, 2000-2004, 2005-2009, and 2010-2013. Time trends in stone incidence were assessed by Poisson regression. The prevalence of stone disease for the years 1999-2013 was also determined.

RESULTS

Almost all the 190 patients (97%) that we identified had symptomatic stones, and acute flank or abdominal pain and hematuria were the most common presenting features. The total annual incidence of kidney stones increased from 3.7/100,000 in the first 5-year interval to 11.0/100,000 during the years 1995-2004 (p < 0.001) and decreased thereafter to 8.7/100,000 in 2010-2013 (p = 0.63). The incidence rise was highest in girls aged 13-17 years, in whom it rose from 9.8/100,000 in 1985-1989 to 39.2/100,000 in 2010-2013 (p < 0.001), resulting in an overall female predominance in this age group. The mean annual prevalence of stone disease in 1999-2013 was 48/100,000 for boys and 52/100,000 for girls.

CONCLUSION

We found a significant increase in the incidence of childhood kidney stone disease, driven by a dramatic increase of stone frequency in teenage females which is poorly understood and warrants further study.

Super-mini percutaneous nephrolithotomy for renal stone less than 25mm in pediatric patients: Could it be an alternative to shockwave lithotripsy?

AIM

To evaluate the efficacy of 2 different techniques: shock wave lithotripsy (SWL) vs. super-mini percutaneous nephrolithotomy (SMP), in terms of success as well as complication rates in pediatric renal stones sizing<25mm.

PATIENTS AND METHODS

A total of 219 children (aging between 1-17 years) undergoing 2 different treatment modalities (SWL vs. SMP) for kidney stones<25mm were included. Depending on the type of the procedure applied, children were divided into 2 different groups: group 1 (n=108), children treated with SWL, and group 2 (n=111), children treated with SMP. All treatment related parameters (stone free rates, number of sessions, treatment duration, hospitalization, presence of the residual fragments, complications as well as the need for additional interventions) were noted and evaluated between 2 groups in a comparative manner.

RESULTS

Evaluation of our data have clearly demonstrated that the percentage of residual fragments after SWL was significantly higher when compared with SMP. Although SWL required several sessions under general anesthesia in a certain per cent of the cases (54.6%), SMP was successful in one session in all of the cases. Last but not least, in addition to the similar minor complication rates observed in both group of cases, no major complication observed in any case and no case in both groups again required blood transfusion after these 2 procedures with no significant drop rates in hemoglobin levels.

CONCLUSIONS

Although SWL is still the preferred treatment modality for the majority of kidney stones in children due to its safe and non-invasive nature, SMP modality may be applied as a valuable alternative in this specific patient population for its excellent stone free rates obtained in a single session and acceptable complication rates in the minimal invasive management of stones<25mm.

Stones in pregnancy and pediatrics

Urinary stone disease is a highly prevalent condition affecting approximately 10% of the population, and has increased in incidence significantly over the past 20 years. Along with this, the rate of stone disease among women and children is also on the rise. The management of stone disease in specific populations, such as in children and during pregnancy can present unique challenges to the urologist. In both populations, a multi-disciplinary approach is strongly recommended given the complexities of the patients. Prompt and accurate diagnosis requires a high degree of suspicion and judicious use of diagnostic imaging given the higher risks of radiation exposure. In general, management proceeds from conservative to more invasive approaches and must be individualized to the patient with careful consideration of the potential adverse effects. However, innovations in endourologic equipment and techniques have allowed for the wider application of surgical stone treatment in these patients, and significant advancement in the field. This review covers the history and current advances in the diagnosis and management of stone disease in pregnant and pediatric populations. It is paramount for the urologist to understand the complexities of properly managing stones in these patients in order to maximize treatment efficacy, while minimizing complications and morbidity.

Metabolic evaluation of children with urolithiasis

Aim:

The aim of the study is to identify the prevalence of metabolic abnormalities in children with urolithiasis.

Materials and Methods:

This is a prospective study; all children below 15 years who are found to have urolithiasis were prospectively evaluated with relevant history, clinical examination, and urine and serum testing. Metabolic workup includes complete urine examination, urine culture and sensitivity, and 24-h urinary analysis (lithorisk profile).

Results:

A total of 55 patients are included in the study. Forty-two are boys and 13 are girls aged between from 8 months to 15 years. Thirty-three patients underwent stone analysis, primary composition of calcium oxalate stones in 19 (58%), ammonium urate in 4, dahlite in 3 and uric acid in 3, silicon oxide in 2, and struvite in 2 cases. Lithorisk profile was performed in 40 cases (72.7%). The pH range is 5.6–6.2. We noted hypercalciuria in 20 patients (50%), hyperuricosuria in 23 (57.5%), hyperoxaluria in 20 (50%), hypernatriuria in 26 (65%), hypocitraturia in 9 (23%), and hypomagnesuria in 3 (7.5%). Urine calcium-to-creatinine ratio >0.2 was found in 22 (55%) patients. Statistically significant association between hyperoxaluria and hyperuricosuria (P < 0.04, r = 0.32) and hypercalciuria and hyperuricosuria (P < 0.001, r = 0.51) found in this study. Hyperuricosuria is seen in 75% and 73% of patients with hypercalciuria and hyperoxaluria, respectively. Twenty-five children have both lithorisk profile and stone analysis. Hypercalciuria and hyperoxaluria were noted in 60% of calcium oxalate stone formers each. Elevated urinary calcium/creatinine ratio (>0.2) was seen in 73% of calcium oxalate stone formers.

Conclusion:

Because of high prevalence of metabolic risk factors and the significant risk of lifelong recurrence, all children with urolithiasis need complete evaluation with metabolic workup.

Medical and dietary interventions for preventing recurrent urinary stones in children

BACKGROUND

Nephrolithiasis, or urinary stone disease, in children causes significant morbidity, and is increasing in prevalence in the North American population. Therefore, medical and dietary interventions (MDI) for recurrent urinary stones in children are poised to gain increasing importance in the clinical armamentarium.

OBJECTIVES

To assess the effects of medical and dietary interventions (MDI) for the prevention of idiopathic urinary stones in children aged from one to 18 years.

SEARCH METHODS

We searched multiple databases using search terms relevant to this review, including studies identified from the Cochrane Central Register of Controlled Trials (CENTRAL, 2017, Issue 1), MEDLINE OvidSP (1946 to 14 February 2017), Embase OvidSP (1980 to 14 February 2017), International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov. Additionally, we handsearched renal-related journals and the proceedings of major renal conferences, and reviewed weekly current awareness alerts for selected renal journals. The date of the last search was 14 February 2017. There were no language restrictions.

SELECTION CRITERIA

Randomized controlled trials of at least one year of MDI versus control for prevention of recurrent idiopathic (non-syndromic) nephrolithiasis in children.

DATA COLLECTION AND ANALYSIS

We used standard methodologic procedures expected by Cochrane. Titles and abstracts were identified by search criteria and then screened for relevance, and then data extraction and risk of bias assessment were carried out. We assessed the quality of evidence using GRADE.

MAIN RESULTS

The search identified one study of 125 children (72 boys and 53 girls) with calcium-containing idiopathic nephrolithiasis and normal renal morphology following initial treatment with shockwave lithotripsy (SWL). Patients were randomized to oral potassium citrate 1 mEq/kg per day for 12 months versus no specific medication or preventive measure with results reported for a total of 96 patients (48 per group). This included children who were stone-free (n = 52) or had residual stone fragments (n = 44) following SWL. Primary outcomes:Medical therapy may lower rates of stone recurrence with a risk ratio (RR) of 0.19 (95% confidence interval (CI) 0.06 to 0.60; low quality evidence). This corresponds to 270 fewer stone recurrences per 1000 (133 fewer to 313 fewer) children. We downgraded the quality of evidence by two levels for very serious study limitations related to unclear allocation concealment (selection bias) and a high risk of performance, detection and attrition bias. While the data for adverse events were incomplete, they reported that six of 48 (12.5%) children receiving potassium citrate left the trial because of adverse effects. This corresponds to a RR of 13.0 (95% CI 0.75 to 224.53; very low quality evidence); an absolute effect size estimate could not be generated. We downgraded the quality of evidence for study limitations and imprecision.We found no information on retreatment rates.

SECONDARY OUTCOMES

We found no evidence on serum electrolytes, 24-hour urine collection parameters or time to new stone formation.We were unable to perform any preplanned secondary analyses.

AUTHORS' CONCLUSIONS

Oral potassium citrate supplementation may reduce recurrent calcium urinary stone formation in children following SWL; however, our confidence in this finding is limited. A substantial number of children stopped the medication due to adverse events. There is no trial evidence on retreatment rates. There is a critical need for additional well-designed trials in children with nephrolithiasis.

Stone growth patterns and risk for surgery among children presenting with hypercalciuria, hypocitraturia and cystinuria as underlying metabolic causes of urolithiasis

INTRODUCTION

Hypercalciuria, hypocitraturia and cystinuria are the most common underlying metabolic stone abnormalities in children. The present study compared stone growth patterns, stone burden, and the risk of stone-related surgery among these underlying metabolic conditions.

METHODS

A retrospective cohort of 356 children with renal stones, followed from 2000 to 2015, was studied. Differences among metabolic groups were determined using Kruskal-Wallis test; the Scheffé-test was used for multiple comparisons to determine differences among single groups. Independent sample t-test was used when adequate, given the sample size, and Chi-squared test was used for categorical variables. Stone growth rates were calculated as differences in diameter divided by time elapsed between U/Ss (mm/year). Logistic regression was performed to assess the effect of initial stone size on the likelihood of surgery.

RESULTS

Median stone size at presentation was significantly different among groups, with cystinuria being the group with the largest proportion of stones >10 mm, while patients with stones <5 mm were likely to have a normal metabolic workup (P < 0.05). Stones with a higher growth rate were found in the operative group, while slower growing stones were mostly managed conservatively (3.4 mm/year vs 0.8 mm/year, respectively; P = 0.014). However, stone growth rates were not significantly different among metabolic groups. On the other hand, the rate of new stone formation in cystinuric patients at their first follow-up was 30.4%, which was significantly higher than in patients with hypercalciuria (16.3%) or with a normal metabolic workup (17.2%; P < 0.05). Compared with stones <5 mm, stones measuring 5-10 mm were more than four times more likely to result in surgery, whereas the likelihood of surgery for 10-20 mm or >20 mm stones was almost 16 or 34 times, respectively (P < 0.001).

CONCLUSIONS

It is believed that this is the first study to evaluate stone growth patterns, stone burden and surgical risk among children with hypercalciuria, hypocitraturia and cystinuria. Cystinuric patients presented with larger stones at the time of diagnosis, higher new stone formation rates, and were at higher risk of surgery. While no significant difference of growth rate was found among metabolic groups, stones with a higher growth rate were significantly more likely to result in surgical treatment than slower growing stones. Initial stone size, location of largest stone, previous urinary tract infection, and patient's metabolic type significantly influenced the likelihood of a surgical intervention. Better understanding of the natural history ultimately helps surgeons and clinicians defining prognosis, treatment, and prevention plans for pediatric urolithiasis.

Mass Spectrometry-based in vitro Assay to Identify Drugs that Influence Cystine Solubility

Cystinuria is a rare genetic disorder characterized by recurrent, painful kidney stones, primarily composed of cystine, the dimer of the amino acid cysteine (Sumorok and Goldfarb, 2013). Using a mouse model of cystinuria, we have recently shown that administration of drugs that increase cystine solubility in the urine can be a novel therapeutic strategy for the clinical management of the disease (Zee et al., 2017). There is a large unmet need in the field for developing new drugs for cystinuria. To that end, here we describe a simple in vitro cystine solubility assay that is amenable for screening compounds to identify potential drugs that may influence cystine solubility. The assay includes preparing a supersaturated solution of cystine, incubating this solution with drug(s) of choice, and finally using high pressure liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to quantify the amount of cystine precipitated under various conditions.