Evaluation and medical management of kidney stones in children

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.

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.

Renal calcification in children with renal tubular acidosis: What a paediatrician ‎should ‎know‎

Renal tubular acidosis (RTA) can lead to renal calcification in children, which can cause various complications and impair renal function. This review provides pediatricians with a comprehensive understanding of the relationship between RTA and renal calcification, highlighting essential aspects for clinical management. The article analyzed relevant studies to explore the prevalence, risk factors, underlying mechanisms, and clinical implications of renal calcification in children with RTA. Results show that distal RTA (type 1) is particularly associated with nephrocalcinosis, which presents a higher risk of renal calcification. However, there are limitations to the existing literature, including a small number of studies, heterogeneity in methodologies, and potential publication bias. Longitudinal data and control groups are also lacking, which limits our understanding of long-term outcomes and optimal management strategies for children with RTA and renal calcification. Pediatricians play a crucial role in the early diagnosis and management of RTA to mitigate the risk of renal calcification and associated complications. In addition, alkaline therapy remains a cornerstone in the treatment of RTA, aimed at correcting the acid-base imbalance and reducing the formation of kidney stones. Therefore, early diagnosis and appropriate therapeutic interventions are paramount in preventing and managing renal calcification to preserve renal function and improve long-term outcomes for affected children. Further research with larger sample sizes and rigorous methodologies is needed to optimize the clinical approach to renal calcification in the context of RTA in the pediatric population.

Extracorporeal shock wave lithotripsy for treatment of large pediatric renal pelvic stone burden more than 2 cm

BACKGROUND

The high recurrence rates in pediatric urolithiasis indicate the need for none invasive or a minimally invasive treatment such as SWL. Therefore, EAU, ESPU and AUA recommend SWL as a first line treatment for renal calculi ≤ 2, and RIRS or PCNL for renal calculi > 2 cm. SWL is superior to RIRS and PCNL as it is inexpensive, outpatient procedure, and it has a high SFR in well selected cases specially pediatrics. On the other hand, SWL therapy has a limited efficacy with a lower SFR, and high retreatment rate and/or additional interventions for treatment of larger and harder renal calculi.

OBJECTIVE

We carried out this study to evaluate the efficacy and safety of SWL for treatment of renal stones > 2 cm to extend its indications for pediatric renal calculi.

METHODS

Between January 2016 and April 2022, we reviewed the records of patients with renal calculi treated by SWL, mini-PCNL, RIRS and open surgery in our institution. Forty-nine eligible children aged 1-5 years old, presented with renal pelvic and/or calyceal calculi measuring 2-3.9 cm and underwent SWL therapy were picked up and participated in the study. The data of an additional eligible 79 children with the same age and had renal pelvic and/or calyceal calculi > 2 cm up to stag horn calculi and underwent mini-PCNL, RIRS and open renal surgery were also picked up and participated in the study. We retrieved the following preoperative data from the records of the eligible patients; age, gender, weight, length, radiological findings (stone size, side, site, number and radio-density), renal function tests, routine laboratory findings, and urine analysis. The outcomes data in the form of; operative time, fluoroscopy time, hospital stay, SFRs, retreatment rates and complication rates were also retrieved from the records of patients treated with SWL and other techniques. Also, we collected the SWL characteristics in terms of; position, number and frequency of shocks, voltage, time of the session and U/S monitoring to assess stone fragmentation. All SWL procedures were performed according to the institution's standards.

RESULTS

The mean age of patients treated with SWL was 3.23 ± 1.19 years old, the mean size of the treated calculi was 2.31 ± 0.49 and the mean length of the SSD was 8.2 ± 1.4 cm. All patients had NCCT scan and the mean radio-density of the treated calculi was 572 ± 169.08 HUs based on NCCT scans Table (1). Single- and two-session SFRs of SWL therapy were 75.5% (37/49 patients) and 93.9% (46/49 patients), respectively. The overall success rate was 95.9% (47/49 patients) after three-session of SWL. Complications experienced by 7 patients (14.3%) in the form of fever (4.1%), vomiting (4.1%), abdominal pain (4/1%), and hematuria (2%). All complications were managed in outpatient settings. Our results were obtained on the basis of preoperative NCCT scans for all patients and postoperative plain KUB films and real-time abdominal U/S. Furthermore, single-session SFRs for SWL, mini-PCNL, RIRS and open surgery were 75.5%, 82.1%, 73.7% and 90.6%, respectively. Two-session SFRs by the same technique were 93.9%, 92.8%, and 89.5% for SWL, mini-PCNL and RIRS, respectively. A lower overall complication rate and higher overall SFR were found with SWL therapy compared to other techniques, Fig. (1).

DISCUSSION

Being a non-invasive outpatient procedure with a low complication rate and good spontaneous passage of stone fragments is the main advantage of SWL. In this study, the overall SFR is 93.9% where 46 out of 49 patients were completely rendered stone free after three session of SWL with overall success rate 95.9%. Badawy et al. reported overall success rates of 83.4% for renal stones with a mean stone size of 12.5 ± 7.2 mm. In children with renal stones measuring 18.2 mm, Ramakrishnan et al. reported a 97% SFR in accordance with our results. The high overall success rate (95.9%) and SFR (93.9%) in our research were attributed to the regular use of ramping procedure, low shock wave rate, percussion diuretics inversion (PDI) approach and alpha blocker therapy in all participants and short SSD. The limitations of our study are small sample of patients and its retrospective nature.

CONCLUSION

The non-invasive nature and replicability of the SWL procedure, along with the high success and low complication rates, give us a new insight to consider its application for treating pediatric renal calculi > 2 cm over the other more invasive techniques. Short SSD, the use of ramping procedure, low shock wave rate, 2 min break, PDI approach and alpha blockers therapy help better success of SWL.

LEVEL OF EVIDENCE

IV.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSION

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

Experience of high polymer gel pad assisted ultrasound monitoring in the treatment of infant urolithiasis during extracorporeal shock wave lithotripsy

In the extracorporeal shock wave lithotripsy for infants, we used a medical polymer gel pad to assist ultrasonic positioning, so that the ultrasonic probe could be far away from the shock wave energy field. Although not affecting the ultrasonic positioning and monitoring effect, we discussed the protective effect of this method on the ultrasonic probe. A retrospective analysis was made on 21 infants (0-3 years old) who received ESWL in our hospital from June 2021 to February 2023. After the stones were accurately located by B-ultrasound before surgery, a 4 * 5 * 10 cm medical polymer gel pad was placed between the skin and the ultrasonic probe to keep the ultrasonic probe away from the shock wave energy field. The B-ultrasonic wave source locked the target stone through the gel pad, and the lithotripter Dornier Compact Delta II was used for lithotripsy. The extracorporeal shock wave lithotripsy was completed under the whole process of B-ultrasonic monitoring. All patients completed the surgery under ultrasound monitoring, and there were no abnormalities in the ultrasound probe during the surgery. The average stone size was 0.60 ± 0.21 cm, the surgical time was 39.8 ± 13.8 min, and the total energy of lithotripsy was 7.41 ± 4.35 J. There were no obvious complications in all patients after the surgery. After 2 weeks of ultrasound examination, the success rate of lithotripsy in 21 patients reached 85.7%. We believe that the use of the gel pad increases the distance between the ultrasonic probe and the skin, leaving the probe away from the shock wave energy field, avoiding the damage of the shock wave source to the ultrasonic probe, and does not affect the monitoring effect of ultrasound on stones and the success rate of lithotripsy, which is worthy of further promotion in the field of children's urinary stones.

Application of ultrasound imaging in the treatment of urinary tract stones

Urinary tract stones are a common clinical condition that affect millions of individuals worldwide. The management of these stones has evolved significantly over the past 70 years, and ultrasound imaging has emerged as a valuable tool for diagnosis, treatment planning, and follow-up. This review aims to provide an overview of the application of ultrasound imaging in the treatment of urinary tract stones, highlighting its advantages, limitations, and current advancements in the field.

Pediatric Mini-Percutaneous Nephrolithotomy Using Self-Retained Screwed Amplatz Sheath Versus Ordinary Sheath

Objective: To evaluate the use of a new 16F mini-screwed sheath in pediatrics in comparison to a 16F ordinary Amplatz sheath. Methods: Sixty-seven patients <18 years with renal calculi between 1 and 2 cm who was a candidate for mini-percutaneous nephrolithotomy (mini-perc) between January 2019 and September 2021 were randomized by closed envelope in group A (34 patients) using new mini-screwed sheath and group B (33 patients) with ordinary mini-sheath. Patients with contraindications for percutaneous nephrolithotomy were excluded. Results: No significant difference was present between both groups according to patients and stone demographics. There was no significant difference between both groups regarding puncture site and number. The mean operative time was 51.25 ± 2.15 minutes and 52.35 ± 3.45 minutes in groups A and B, respectively. The fluoroscopy time was significantly lower in group A (2.1 ± 0.85 minutes) than in group B (2.9 ± 1.05 minutes). Tract loss was 18.2% in group B while 0% in group A. Although bleeding was less in group A, it was nonsignificant. The stone-free rate was (94.11%) and (90.9%) in group A and group B, respectively. Conclusion: Screwed sheath enables the urologist to have a stable track during pediatric mini-perc surgery despite the thin abdominal wall in the pediatric. The screw sheath provides significantly lower fluoroscopy time and decreases the need for nephrostomy tube insertion when compared with ordinary sheath in mini-perc renal surgery.

Dietary management of hypocitraturia in children with urolithiasis: results from a systematic review

PURPOSE

Hypocitraturia is a low urinary excretion of citrate and a well-known risk factor for kidney stone development in children. This systematic review aimed to evaluate the dietary management of hypocitraturia in children with urolithiasis.

METHODS

Literature search was performed on 30th September 2022 using Embase, PubMed, and Cochrane Central Controlled Register of Trials. Studies were included if children with stones and hypocitraturia were managed with diet supplements.

RESULTS

Six papers were included. Four studies evaluated the role of oral potassium citrate associated with high fluid intake on stone resolution and recurrence. Two studies assessed the impact of oral potassium citrate on long-term stone recurrence after percutaneous nephrolithotomy and shock wave lithotripsy. All studies demonstrated that the association of potassium citrate and high fluid intake was well tolerated with no side effects and restored normal urine citrate excretion, allowed a reduction in stone size, and, following definitive treatments, was associated with a lower rate of stone regrowth and recurrence compared with controls. These effects were demonstrated across all pediatric ages.

CONCLUSIONS

Our review infers that oral potassium citrate and high fluid assumption are safe and effective in restoring urine citrate excretion, treating and preventing stone recurrence with no serious adverse events, and should probably be the first-line treatment of pediatric patients with asymptomatic stones and hypocitraturia.

Shockwaves and the Rolling Stones: An Overview of Pediatric Stone Disease

Urinary stone disease is a common problem in adults, with an estimated 10% to 20% lifetime risk of developing a stone and an annual incidence of almost 1%. In contrast, in children, even though the incidence appears to be increasing, urinary tract stones are a rare problem, with an estimated incidence of approximately 5 to 36 per 100,000 children. Consequently, typical complications of rare diseases, such as delayed diagnosis, lack of awareness, and specialist knowledge, as well as difficulties accessing specific treatments also affect children with stone disease. Indeed, because stone disease is such a common problem in adults, frequently, it is adult practitioners who will first be asked to manage affected children. Yet, there are unique aspects to pediatric urolithiasis such that treatment practices common in adults cannot necessarily be transferred to children. Here, we review the epidemiology, etiology, presentation, investigation, and management of pediatric stone disease; we highlight those aspects that separate its management from that in adults and make a case for a specialized, multidisciplinary approach to pediatric stone disease.

Enteral nutrition and the risk of nephrolithiasis in complex pediatric patients

PURPOSE

Medically complex, non-ambulatory children can often suffer from nephrolithiasis. The purpose of this study is to determine risk factors which are predictive for recurrent stone formation in this patient population.

MATERIAL AND METHODS

A retrospective cohort study was performed on non-ambulatory patients with cerebral palsy and/or severe developmental delay presenting to a high-volume Pediatric Stone Center from 2015 to 2019. Two 24-hour urine collections were performed as a baseline prior to pharmacotherapeutic and/or dietary intervention. Healthy stone-forming children served as a control group.

RESULTS

28 non-ambulatory subjects and 38 healthy controls were evaluated. The study group had a higher rate of bilateral nephrolithiasis but a similar history of previous surgical procedures. 89% of the non-ambulatory children were fed via a gastrostomy. The median calcium excretion was the same in both groups (3.0 mg/kg/day). The median 24-hour excretion of oxalate was significantly increased in the study group (54 vs 31 mg/1.73 m²/day, p = 0.0001). Urinary citrate and phosphorus excretions, and the supersaturations of calcium oxalate and calcium phosphate were similar between study subjects and controls. Calcium oxalate stones were noted in 57% of those with known stone composition in the study group. Enteral feeding formulas were primarily based on soy protein, a known high oxalate food.

CONCLUSIONS

Urinary oxalate excretion is significantly increased in a cohort of medically complex, non-ambulatory stone-forming children. Urinary calcium excretion was not elevated between study subjects and healthy controls. Further analysis is needed to assess if dietary intervention to limit oxalate excretion results in decreased stone formation.

Do dietary factors play a role in infantile urolithiasis?

BACKGROUND

Urolithiasis is a significant cause of morbidity that may be diagnosed at a young age. However, there is little research on the role of nutrition in pediatric urolithiasis, and research on the infantile period is extremely rare. The aim of this study is to investigate the effect of dietary factors on those diagnosed with "idiopathic" infantile urolithiasis.

METHOD

The study group included 44 infants without a proven etiological factor for urolithiasis. The control group consisted of 60 fully healthy infants of matched age and gender. The parents and caregivers of each infant in the patient and control groups were carefully questioned by the same researcher for their dietary characteristics.

RESULT

The duration of formula usage and daily volume of formula were statistically higher in the study group than the control group (p = 0.041 and p = 0.003, respectively). The urolithiasis group consumed significantly more cow's milk and dairy products (p = 0.033 and p = 0.001). There was no statistically meaningful difference between the two groups in terms of starting age for free water and salty food, as well as daily water intake.

CONCLUSION

We concluded that dietary conditions could also be a risk factor for idiopathic urolithiasis. We believe that nutritional factors for infantile urolithiasis should be better described, in addition to genetic, anatomical, and metabolic factors. A higher resolution version of the Graphical abstract is available as Supplementary information.

Management of pediatric ureterolithiasis in the emergency room: A single institution review and new management pathway

INTRODUCTION/BACKGROUND

Urolithiasis is an increasingly common condition seen in children with an annual incidence of 2-3% in children under 18, and up to 10% in adolescents. Treatment of stones varies including observation, IV hydration, pain management, medical expulsive therapy (MET), or surgery. Though well-studied and often used in adults, MET (alpha-adrenergic antagonists to facilitate passage of ureteral stones), is not routinely prescribed in pediatric patients.

OBJECTIVE

The goals of this study were to review a quaternary children's hospital's emergency room frequency of MET utilization for ureterolithiasis as well as evaluate the clinical outcomes of children who were prescribed MET compared to those treated with pain control alone.

STUDY DESIGN

A retrospective review was performed of children 2 months to 18 years with ureterolithiasis who presented to a quaternary children's hospital ED from 2011 to 2017. The primary outcome was the frequency of MET prescribed. Secondary outcomes included the following comparisons in patients who received MET and analgesics with those who received analgesics alone: hospital admission rate, length of hospitalization, emergency room re-presentation rate, surgical intervention, spontaneous stone passage, urology consultation, how the urology consult affected MET utilization, referral to outpatient urology and nephrology clinics, and CT utilization in the ED. Comparisons were performed utilizing Fischer's exact and t-tests.

RESULTS

139 patients were included with a mean age of 14 years (SD 4.14), 42% male. There was no difference between age, gender, stone size, return to the ED, serum creatinine, or length of hospitalization (if admitted) between patients who were and were not placed on MET. The rate of stone passage was significantly higher for those placed on MET (45%) versus not (20%) (p = 0.0022). Urology was consulted for 93% of the cases where children were prescribed MET, compared with only 52% of cases where MET was not prescribed (p = <0.0001).

DISCUSSION

In our experience MET was significantly underutilized in patients where urology was not involved. This is similar to a study by Itano et al. which found urology consultation in the ED significantly increased use of tamsulosin for ureterolithiasis in adults. Children with ureterolithiasis placed on MET had a significantly higher rate of stone passage compared to children managed by pain control alone.

CONCLUSION

Given the benefits of MET to increase the rate of spontaneous stone passage it may be considered first line therapy for treatment of children with ureterolithiasis.

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 Impact of Water and Other Fluids on Pediatric Nephrolithiasis

Pediatric nephrolithiasis cases have been on the rise in the past several years, resulting in increased healthcare costs and other burdens on the juveniles with this ailment. Recent research has shown that present trends in pediatric nephrolithiasis have changed as a result of fluid intake, including water consumption, nutrition, obesity prevalence, lifestyle, and imaging procedures. A specific cause, meanwhile, is still elusive. Trends in pediatric nephrolithiasis need to be thoroughly researched. Furthermore, variables specific to pediatric nephrolithiasis that could cause greater difficulties in an affected child elevate the level of worry with cumulative prevalence. Doctors should rigorously assess patients who present with kidney stones when they have dynamics such as varied clinical presentation, high recurrence of kidney stones linked to metabolic and urinary tract problems, and the potential existence of rare genetic kidney stone illnesses. This review aims to identify adaptive risk factors and anomalies that call for specialized treatment and prescription. More specifically, the major goals of medical and surgical treatments are to eliminate kidney stone risk and stop relapse while concurrently lowering interventional barriers. A dedicated nephrolithiasis clinic run by a pediatric nephrologist, nutritionist, urologist, and clinical nurse may sometimes be beneficial for patients in serious danger. Such a clinic offers significant chances to learn more about pediatric nephrolithiasis, which has been linked to water consumption and hence fosters urgently required study in this area.

Hydroxyproline stimulates inflammation and reprograms macrophage signaling in a rat kidney stone model

Meals rich in oxalate are associated with calcium oxalate (CaOx) kidney stone disease. Hydroxy-L-proline (HLP) is an oxalate precursor found in milk and collagen-containing foods. HLP has been shown to induce CaOx crystal formation in rodents. The purpose of this study was to evaluate the effect of HLP induced oxalate levels on inflammation and renal leukocytes during crystal formation. Male Sprague-Dawley rats (6-8 weeks old) were fed a control diet containing no oxalate for 3 days before being randomized to continue the control diet or 5% HLP for up to 28 days. Blood, 24 h urine, and kidneys were collected on Days 0, 7, 14, or 28. Urinary oxalate levels, crystal deposition, and renal macrophage markers were evaluated using ion chromatography-mass spectrometry, immunohistochemistry, and qRT-PCR. Renal leukocytes were assessed using flow cytometry and RNA-sequencing. HLP feeding increased urinary oxalate levels and renal crystal formation in animals within 7 days. HLP also increased renal macrophage populations on Days 14 and 28. Transcriptome analysis revealed that renal macrophages from animals fed HLP for 7 days were involved in inflammatory response and disease, stress response to LPS, oxidative stress, and immune cell trafficking. Renal macrophages isolated on Day 14 were involved in cell-mediated immunological pathways, ion homeostasis, and inflammatory response. Collectively, these findings suggest that HLP-mediated oxalate levels induce markers of inflammation, leukocyte populations, and reprograms signaling pathways in macrophages in a time-dependent manner. Additional studies investigating the significance of oxalate on renal macrophages could aid in our understanding of kidney stone formation.

Analysis of potential risk factors associated with urolithiasis

OBJECTIVES

Eating habits, regular fluid intake, lifestyle and body composition are a primary point of research. The research focused on urolithiasis approaching potential danger, trying to interpret risk factors responsible for urolithiasis and disease recurrence.

METHODS

Research file contains 166 patients suffering from urolithiasis, 87 (52.4%) males and 79 (47.6%) females, and 172 healthy subjects from control group. All data was accessed using fully anonymous and confidential questionnaires, then evaluated in the statistical GNU PSPP 1.4 software.

RESULTS

More than 3/4 patients have a BMI higher than 24.9 and almost 40% of subjects have obesity class I, II, or III. Patients have higher BMI than subjects (d = 1.285; p < 0.001), and females have significantly higher BMI than males (d = 0.385; p = 0.007). Female patients have higher BMI than Slovak healthy females (p < 0.001; MD = 4.581; CI: 3.24-5.93). Patients have a lower daily water intake than subjects (φc = 0.157; p = 0.04) and more than ²/3 of patients have insufficient water intake. Sedentary employment prevails markedly in patients than in subjects. Patients are much less physically active than subjects (φc = 0.633; p < 0.001) and the difference is rising with increasing age of patients (ρ = - 0.232; p = 0.003). Low physical and working activity are characteristic for patients in this study. Patients smoke more often in comparison to subjects (φc = 0.261; p < 0.001). Patients consume more meats (red and white), cocoa and lentils. A lot of patients exceed recommended daily intake of pork and beef.

CONCLUSIONS

Many conditions are different for the healthy population and patients' group. High BMI, low fluid intake, exceeded red meat consumption, and low physical activity are the strongest factors for developing urolithiasis. Patients should consume more fluids daily, exercise frequently and vigorously, and lower amount of red meat consumed.

[Renal colic: How to calm and optimize the stone expulsion? Which treatment for pregnant women and children?]

INTRODUCTION

The aims of this narrative review was to report on the contemporary data of renal colic (RC) in terms of epidemiology and pressure on emergency structures and also to describe the latest therapeutic developments about uncomplicated RC, depending on the pediatric, adult and pregnancy population.

MATERIAL AND METHODS

A request to the health surveillance network for emergencies and deaths (SurSaUD®, Santé Publique France) revealed original data on the contemporary epidemiology of renal colic. A narrative synthesis of the articles (French, English) available on the Pubmed database was produced in June 2021.

RESULTS

Renal colic represents 1.1% of the annual total of emergency room visits. The mean age at admission was 45 years and 62% of patients were men. NSAIDs and Paracetamol are the most effective analgesic treatments and should be given priority over opioids. Non-drug analgesic treatments by tactile stimulation probably have a place in the CN management, particularly in case of contraindications. Among the validated treatments, alphablockers allow better expulsion when the stone is located in the pelvic ureter and if its size is between 5 and 10mm in diameter. In pregnant women, the predominant problem is to confirm the diagnostic. If there is a strong suspicion, MRI or a low-dose CT scan is possible. Ureteroscopy is feasible in particular in the first part of pregnancy to avoid iterative ureteral catheter changes. The care for children is now based on that of adults.

CONCLUSION

The renal colic care pathway in 2021 can benefit from various optimizations in the field of expulsion and analgesic treatments. Good knowledge of the specific situations in pregnant women and children allowing to improve the quality of care.

Oxalate Alters Cellular Bioenergetics, Redox Homeostasis, Antibacterial Response, and Immune Response in Macrophages

Individuals with calcium oxalate (CaOx) kidney stones can have secondarily infected calculi which may play a role in the development of recurrent urinary tract infection (UTI). Uropathogenic Escherichia coli (UPEC) is the most common causative pathogen of UTIs. Macrophages play a critical role in host immune defense against bacterial infections. Our previous study demonstrated that oxalate, an important component of the most common type of kidney stone, impairs monocyte cellular bioenergetics and redox homeostasis. The objective of this study was to investigate whether oxalate compromises macrophage metabolism, redox status, anti-bacterial response, and immune response. Monocytes (THP-1, a human monocytic cell line) were exposed to sodium oxalate (soluble oxalate; 50 µM) for 48 hours prior to being differentiated into macrophages. Macrophages were subsequently exposed to calcium oxalate crystals (50 µM) for 48 hours followed by UPEC (MOI 1:2 or 1:5) for 2 hours. Peritoneal macrophages and bone marrow-derived macrophages (BMDM) from C57BL/6 mice were also exposed to oxalate. THP-1 macrophages treated with oxalate had decreased cellular bioenergetics, mitochondrial complex I and IV activity, and ATP levels compared to control cells. In addition, these cells had a significant increase in mitochondrial and total reactive oxygen species levels, mitochondrial gene expression, and pro-inflammatory cytokine (i.e. Interleukin-1β, IL-1β and Interleukin-6, IL-6) mRNA levels and secretion. In contrast, oxalate significantly decreased the mRNA levels and secretion of the anti-inflammatory cytokine, Interleukin-10 (IL-10). Further, oxalate increased the bacterial burden of primary macrophages. Our findings demonstrate that oxalate compromises macrophage metabolism, redox homeostasis, and cytokine signaling leading to a reduction in anti-bacterial response and increased infection. These data highlight a novel role of oxalate on macrophage function.

Determination of the etiology of pediatric urinary stone disease by multigene panel and metabolic screening evaluation

INTRODUCTION

Urinary tract stone disease (UTSD) is seen with increasing frequency in children, and genetic, metabolic and environmental factors are known to play a role in its etiology. Since it is a genetically heterogeneous disease, we investigated the multigene panel and metabolic evaluation together.

MATERIAL AND METHOD

Forty-eight pediatric patients that underwent surgery for UTSD and were followed up in the Department of Urology of Çukurova University Faculty of Medicine between March 2016 and July 2019 were included in the study. Children with known metabolic diseases were excluded.A detailed history was taken from each patient, and presence of a positive family history was questioned. Blood and urine samples were obtained, and metabolic evaluation was performed. In addition, 2 cc peripheral blood samples were collected from selected patients to perform DNA isolation at Çukurova University Adana Genetic Diseases Diagnosis and Treatment Center. The analysis of the obtained sequence data was performed.

RESULTS

Of the 48 children included in the study, 29 (60.4%) were male and 19 (39.6%) were female. The mean age was 60 ± 50 (12-192) months. It was observed that 28 (58.3%) of the patients included in the study had a positive family history.As a result of the next-generation sequencing studies conducted with the multigene panel, a total of 21 clinically significant variants in eight different genes were identified with the bioinformatics analysis on the data on which quality control was performed. The weighted distribution of the 21 variants according to the genes was as follows: five variants (23.8%) in the SLC3A1 gene, four (19%) in SLC6A20, and three (14.3%) in SLC7A9 and SLC26A1. The clinical reporting of the disease etiology and/or variants with prognostic significance determined as a result of the performed analyses was completed by field experts in accordance with international standards. The visuals of the detected variants are presented in Summary figure.

CONCLUSION

In pediatric cases with UTSD, it is important to determine the underlying metabolic and genetic risk factors in order to prevent recurrence and apply the most effective treatment.

24-Hour urine collection for first time pediatric stone formers: Is it worth it?

INTRODUCTION/OBJECTIVE

24-h urine collections are recommended for motivated first-time stone formers. Given that children have a lifetime potential for recurrences, metabolic work-up has been recommended. 24-hour urine collections can be problematic, especially in children. We sought to study the benefits of 24-h urine collections in children with stones.

STUDY DESIGN

We performed a single center, retrospective chart review of the most recent pediatric nephrolithiasis patients under age 18 at our center who supplied their first 24-h urine collection. We assessed whether 24-h urine results led to a change in management and if those patients were adherent to the recommendations.

RESULTS

Seventy pediatric nephrolithiasis patients who had 24-h urine collection were reviewed. Recommendations other than standard dietary and fluid intake changes were made in 8/70 (11%). A low citrate/calcium ratio (327 vs. 525, p < 0.03) and whether the test was ordered by nephrology vs. urology (26% vs. 2%, p < 0.003) were predictive of an additional recommendation. Of the 8 patients who had changes recommended only 1/8 completed a repeat 24-h urine collection, 3/8 never returned for followed up and 2/8 stopped the medicines prior to follow up. There was no difference in early stone recurrence rates, 55% of the studies were incorrectly collected, and total costs are estimated at $9800.

DISCUSSION

Our study aimed to evaluate the impact and value of 24-h urine collection in first time pediatric stone formers. We found that 24-h urine collections altered management from standard dietary recommendations in only 11% of cases. These collections were fraught with challenges - 55% of our samples appeared to be incorrectly collected, there was at least one abnormality noted in 100% of collections, these tests are expensive, and patients were poorly compliant with recommendations based on test results. Additionally, changes made based on the 24-h urine results seemed to vary depending on who evaluated the test results. Among cases in which changes were made, nephrologists made alterations at a far greater rate than urologists did. We do acknowledge there are several limitations to our study. First, this is a retrospective chart review. Second, for the urology patients, we were only able to review patient records that were available due to a transition from one electronic medical record to another, resulting in a loss of some earlier patient records. We highly doubt that those records we could not review were significantly different than those we did review. Third, this is a single center design and includes the practice patterns of the providers here. We acknowledge that our local practice patterns may or may not be reflective of national practice patterns, however, most clinicians are likely faced with similar interpretation issues and poor rates of compliance and could benefit from guidelines.

CONCLUSION

24-h urine collection for first time pediatric stone formers is expensive, difficult to accomplish and infrequently leads to treatment changes. Our data suggest it adds little for most children with stones and may be better reserved for those children with recurrent stone disease.

Mini-percutaneous nephrolithotomy in a child with multiple urogenital anomalies and a solitary duplex kidney

Purpose:

To report a case of successful removal of right staghorn renal calculi in a 3-year-old girl with Arnold-Chiari malformation and multiple urogenital anomalies.

Case report:

A 3-year-old female child with the diagnosis of Arnold-Chiari type 2 malformation was referred to our clinic due to presence of 9 kidney stones with a total volume of 10743mm3. The total of the longest diameters of all stones was calculated as 11.4cm. The patient had a urogenital septum, bifid bladder, and duplicated collecting system on the right side. An 18F Amplatz sheath was placed and mini-percutaneous nephrolithotomy was performed successfully by laser and pneumatic lithotripter. Any residual urinary tract stones or urinary tract infection were not detected during the 6th-month follow-up.

Conclusion:

Urolithiasis requires a thorough understanding of the underlying causes, as well as an effective and minimally invasive treatment. It is important for urologists to understand the complexity of the optimal stone management in pediatric patients in order to maximize treatment efficacy and minimize morbidity. We conclude that it is essential to treat urolithiasis in a single session in children with urogenital anomalies and accompanying congenital anomalies who have past surgical history.

Hypertonic saline-induced urolithiasis presenting as acute renal failure in a child with traumatic brain injury: A case report

We report the case of a 4 year old female with severe traumatic brain injury who developed bilateral obstructing ureteral stones after hypertonic saline treatment. She developed calcium phosphate stones after two weeks of hypertonic saline therapy, and was successfully treated with ureteral stents and ureteroscopy. She has remained stone-free since that time. We postulate that an incomplete type 1 renal tubular acidosis made her intolerant to the acid and sodium load of the saline, and discuss other lithogenic factors of her presentation.

Pure xanthine pediatric urolithiasis: A cause of acute renal failure

Xanthine urolithiasis is usually a benign condition, easy to prevent or cure by appropriate alkalinization, forced hydration and restriction of dietary purines if diagnosed early. When unrecognized, xanthinuria can lead to end-stage renal failure or nephrectomy.

Imaging modalities and treatment of paediatric upper tract urolithiasis: A systematic review and update on behalf of the EAU urolithiasis guidelines panel

BACKGROUND

Prompt diagnosis and treatment of paediatric urolithiasis are required to avoid long term sequelae of renal damage.

OBJECTIVE

To systematically review the literature regarding the diagnostic imaging modalities and treatment approaches for paediatric urolithiasis.

STUDY DESIGN

PubMed, Science Direct, Scopus and Web of Science were systematically searched from January 1980-January 2019. 76 full-text articles were included.

RESULTS

Ultrasound and Kidney-Ureter-Bladder radiography are the baseline diagnostic examinations. Non-contrast Computed Tomography (CT) is the second line choice with high sensitivity (97-100%) and specificity (96-100%). Magnetic Resonance Urography accounts only for 2% of pediatric stone imaging studies. Expectant management for single, asymptomatic lower pole renal stones is an acceptable initial approach, especially in patients with non-struvite, non-cystine stones<7 mm. Limited studies exist on medical expulsive therapy as off-label treatment. Extracorporeal shock wave lithotripsy (SWL) is the first-line treatment with overall stone free rates (SFRs) of 70-90%, retreatment rates 4-50% and complication rates up to 15%. Semi-rigid ureteroscopy is effective with SFRs of 81-98%, re-treatment rates of 6.3-10% and complication rates of 1.9-23%. Flexible ureteroscopy has shown SFRs of 76-100%, retreatment rates of 0-19% and complication rates of 0-28%. SFRs after first and second-look percutaneous nephrolithotomy (PNL) are 70.1-97.3% and 84.6-97.5%, respectively with an overall complication rate of 20%. Open surgery is seldom used, while laparoscopy is effective for stones refractory to SWL and PNL. Limited data exist for robot-assisted management.

CONCLUSIONS

In the initial assessment of paediatric urolithiasis, US is recommended as first imaging modality, while non-contrast CT is the second option. SWL is recommended as first line treatment for renal stones <20 mm and for ureteral stones<10 mm. Ureteroscopy is a feasible alternative both for ureteral stones not amenable to SWL as well as for renal stones <20 mm (using flexible). PNL is recommended for renal stones >20 mm.

Elevated non-high-density lipoprotein cholesterol corresponds to a high risk of nephrolithiasis in children

Background

Dyslipidemia contributes to the development of nephrolithiasis in adults; however its relationship to urolithiasis in children remains debatable, and will be clarified in the present work.

Methods

A case–control study was performed involving 58 pediatric patients diagnosed with upper urinary tract stones as well as 351 controls. Age, gender, body mass index (BMI), serum calcium, serum uric acid, blood glucose, blood lipids, and compositions of stones were compared.

Results

According to the univariate analysis, uric acid was higher (P < 0.01) but serum calcium lower in the stone group than the control (P < 0.05). As for the blood lipids, non-high-density lipoprotein cholesterol (non-HDL-c) was significantly higher in the stone group as compared to the control (P < 0.01), while total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol did not show statistical difference between the two groups. In the multivariate analysis, only non-HDL-c and serum uric acid were increased in the stone group (P = 0.003 and P = 0.008). In the stone compositions’ analysis, serum uric acid and non-HDL-c were associated with percentage of uric acid and pure calcium oxalate stones, respectively.

Conclusion

Non-high-density lipoprotein cholesterol may act as a lipid risk factor for urolithiasis in children.

What predicts spontaneous passage of ≤1 cm ureteral stones in children?

PURPOSE

The aim of this study is to determine what factors predict spontaneous passage of ≤1 cm ureteral stones in children.

METHODS

Files of the patients diagnosed with a single ureteral stone on a given side between 2008 and 2017 were retrospectively reviewed. Patients with congenital obstructive uropathy, neurogenic bladder, vesicoureteral reflux and those with a stone diameter of >1 cm were excluded. Detection of ureteral stones was done using ultrasonography (US) primarily, and computed tomography when US findings were inconclusive. Patients were treated either conservatively or surgically. Conservative treatment included adequate hydration and pain management whereas surgical treatment included ureteroscopic intervention. Apart from those who required urgent intervention, patients were referred for surgical treatment after 2-4 weeks of follow-up with no spontaneous passage. Factors analyzed for association of spontaneous passage included age, gender, type of hematuria, stone localization, laterality, presence of concomitant kidney stone, degree of hydronephrosis, stone size and stone composition.

RESULTS

A total of 70 patients (38 males, 32 females); median age 4.7 years had a ≤ 1 cm ureteral stone (median diameter 7 mm). US was able to diagnose the ureteric stone in 47 patients while computed tomography was required in 23 patients. Spontaneous passage was observed in 40 patients (57.1%). Median time for stone passage was 8 days (3-34 days). Stone size and presence of hematuria (macroscopic and microscopic combined) were factors associated with spontaneous passage and 6.7 mm was found to be the cut-off (AUC = 0.953; 95% CI 0.905-1.000; sensitivity 96.7%, specificity 82.5%, p < 0.001). Moreover, age, degree of hydronephrosis or stone location were not associated with spontaneous passage.

CONCLUSION

Patients with a ureteric stone size <6.7 mm can safely be followed conservatively, with a spontaneous passage rate of 82.5%. Type of Study Case series with no comparison group. Level of Evidence IV.

Analysis of urine composition from split 24-h samples: use of 12-h overnight samples to evaluate risk factors for calcium stones in healthy and stone-forming children

INTRODUCTION

The analysis of 24-h urine is the gold standard to diagnose metabolic abnormalities in the stone-forming patient. However, urinary composition changes throughout the day and analyzing the whole 24-h urine may mask peaks of increased risk of crystallization.

OBJECTIVE

To examine variations of stone-promoting and stone-inhibiting factors in urine using split 24-h samples from healthy and stone-forming children.

STUDY DESIGN

Urine was collected from 87 healthy and 26 stone-forming children using a split collection procedure (12-h daytime urine and 12-h overnight urine). Urine volume, pH, calcium (Ca), magnesium (Mg), phosphate (P), citrate (Cit), uric acid (Ur), and oxalate (Ox) were determined, and the Ca/Cit ratio was calculated.

RESULTS

The overnight urine samples in both groups had higher levels of P and Mg, lower volume, lower pH, and less citrate and uric acid. As can be seen in the table, higher percentages of healthy and stone-forming children had altered 12-h night urine than 24-h urine with regards to Ca/Cr, Cit/Cr and Ca/Cit ratios. All healthy subjects and all stone-forming children (except one) with altered Cit/Cr ratios or Ca/Cit ratios in the 24-h sample also had altered ratios in the 12-h overnight sample.

DISCUSSION

This study indicates that urine composition changes throughout the day, and that there is daily variability in most of the parameters related to kidney stone formation. Furthermore, 12-h overnight samples seem to be more sensitive than 24-h samples in detecting the most common urinary abnormalities. The main limitation of this study is the relative low sample size of stone-forming children, owing to the low prevalence of nephrolithiasis in childhood.

CONCLUSIONS

We observed a higher excretion of stone-promoting substances and a lower citrate in urine at night. However, the study results do not provide enough evidence to conclude that the use of a 12-h overnight sample collection can replace 24 h urine analysis in the metabolic evaluation of children with lithiasis.

Pediatric Nephrolithiasis: Risk Factors, Evaluation, and Prevention

Pediatric nephrolithiasis is a disease of increasing prevalence and economic burden, with data showing a rising trend among girls and adolescents. Kidney stones in children tend to have a high recurrence rate related to underlying risk factors, and the aim of evaluation should be to understand such causes so that targeted therapy can be provided to decrease recurrence and complications. Metabolic, anatomic, and genetic abnormalities as well as environmental risk factors have all been implicated in the pathogenesis of nephrolithiasis. Recent studies have focused on identifying monogenic causes of nephrolithiasis and/or nephrocalcinosis in young patients that would result in personalization of treatment as well as future diagnostic implications for family members. Treatment aims to decrease stone burden and recurrence as well as minimize complications and is guided by stone size and location as well as surgical expertise. Multidisciplinary care for these patients has been on the rise to provide a more comprehensive medical and surgical support. [Pediatr Ann. 2020;49(6):e262-e267.].

Stone formation in patients less than 20 years of age is associated with higher rates of stone recurrence: Results from the Registry for Stones of the Kidney and Ureter (ReSKU)

INTRODUCTION

Nephrolithiasis is a major source of morbidity in the United States. In recent decades, there has been a notable increase in stone incidence in the pediatric population. We investigate whether recurrent stone formers who had their initial stone episode earlier in life are at risk for more frequent stone recurrences, compared to those with initial episodes later in life. We also examine possible risk factors that might change our approach to treatment of these patients.

METHODS

A review of prospectively collected data from the Registry for Stones of the Kidney and Ureter (ReSKU) from September 2015 to July 2018 was conducted to compare stone recurrence and other patient factors in patients who reported an initial stone episode prior to 20 years of age versus patients who reported an initial stone episode after age 20. Data on patient age, gender, BMI, family history, race, income, infectious symptoms, and number of prior stone episodes was analyzed. We excluded patients with a history of cystinuria stones. Univariate analysis was performed using Fisher's exact test and student's T test. Multivariate analysis was performed using logistic regression.

RESULTS

Of the 1140 patients enrolled during this study period, 472 patients were recurrent stone formers, and of these, 66 had their first stone episode prior to the age of 20. On univariate analysis, early stone formers were more likely to be female, present at a younger age, and have more prior stone episodes on enrollment. Using multivariate modelling to control for age, gender, race, BMI, family history, and number of stone episodes, early stone formers were more likely to be female (CI 1.17 - 3.54) and have more than one prior stone episode (CI 1.13 - 3.78). Late stone formers were more likely to have BMI > 30 (CI 0.26 - 0.94).

CONCLUSION

Recurrent stone formers who have their first episodes prior to age 20 are more likely to present to stone clinics with multiple prior recurrences and hence more aggressive stone disease. Female gender seems to be a risk factor. Earlier stone formers should be encouraged to have close follow up and surveillance due to the increased rate of recurrence. Adult stone databases focusing on early presentations can improve understanding of pediatric stone disease.

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.

Educational review: role of the pediatric nephrologists in the work-up and management of kidney stones

BACKGROUND

The incidence of nephrolithiasis in children and adolescents is increasing and appears to double every 10 years. The most important role of the pediatric nephrologist is to diagnose and modify various metabolic and non-metabolic risk factors, as well as prevent long-term complications especially in the case of recurrent nephrolithiasis.

OBJECTIVE

The purpose of this review is to summarize the existing literature on the etiology and management of pediatric nephrolithiasis.

RESULTS

The incidence of kidney stones is increasing; dietary and environmental factors are probably the main causes for this increased incidence. In most pediatric patients, the etiology for the kidney stones can be identified. Metabolic factors, such as hypercalciuria and hypocitraturia, urinary tract infection, and urinary stasis, constitute leading causes. Herein, we review the etiologies, diagnostic work-up, and treatment options for the most prevalent causes of kidney stones. The detrimental effects of excessive dietary sodium, reduced fluid intake, and the benefits of plant-based over animal-based protein consumption on urinary crystal formation are discussed. We also review the long-term complications.

CONCLUSIONS

Pediatric nephrologists have an important role in the diagnostic work-up and prevention of recurring nephrolithiasis.

Formation of a calcium oxalate urethral stone in a 3-year-old boy due to hypocitraturia

INTRODUCTION

Urolithiasis in children is often due to metabolic abnormalities (e.g. hypocitraturia) and hence recurs frequently.

CASE PRESENTATION

A 3-year-old boy presented with gross hematuria. Computed tomography detected a urethral calculus. The calculus was removed surgically. The stone was composed of calcium oxalate. Although oxalate and uric acid levels in the urine were within normal ranges, urine calcium was moderately elevated and urine citrate was substantially low. Urinalyses of the parents revealed that the father had acidic hypocitraturic urine, containing oxalate crystals, and the mother had hypercalciuria. Administration of oral citrate acid normalized urine citrate levels and eliminated the oxalate crystals, from the boy and his father.

CONCLUSION

Although preventing urolithiasis using oral citrate is common in the adult population, this preventive measure is not well recognized in children, thus warranting further study.

Hydrate Philly: An Intervention to Increase Water Access and Appeal in Recreation Centers

Introduction

Previous interventions to increase water access and consumption have focused on school settings, have shown mixed results on sugar-sweetened beverage (SSB) consumption, and have rarely addressed tap water safety. Our randomized controlled trial examined how improving access and appeal of water in recreation centers in low-income neighborhoods affected counts of SSBs carried by youth attending summer camp.

Methods

Recreation centers (N = 28) matched on their characteristics were randomly assigned to control or intervention groups. Intervention centers received a new water fountain with a bottle filler (hydration station), water testing services, reusable water bottles, and water promotion and education training and materials. Primary outcomes were 1-year changes in center-level average daily gallons of water from fountains and hydration stations (flowmeter readings). Secondary outcomes were counts of SSBs observed, use of bottled water and reusable water bottles, staff SSB consumption, and hydration station maintenance.

Results

Results showed increased water use (b = 8.6, 95% CI, 4.2–13.0) and reusable bottle counts (b = 10.2, 95% CI, 4.2–16.1) in intervention centers compared with control centers. No change occurred in youth carrying SSBs at camp, but center staff’s past 30-day SSB consumption frequency decreased (b = −34.8, 95% CI, −67.7 to −1.9). Intervention sites had marginally lower odds of maintenance problems (OR = 0.09; 95% CI, 0.004–0.76, P = .06) than control sites.

Conclusion

Although providing hydration stations along with water testing, reusable water bottles, education, and promotion increased water consumption among youth at recreation centers, it had no effect on the number of SSBs observed during camp. Future strategies to increase water consumption should also address reducing SSB intake.

The Application of External Ureteral Catheters in Children With Acute Kidney Injury Caused by Ceftriaxone-Induced Urolithiasis

Objective: To evaluate our use of external ureteral catheters in children with acute kidney injury (AKI) resulting from ceftriaxone-induced urolithiasis. Methods: From July 2010 to June 2015, a series of 15 children, including 12 males and 3 females, were referred to our department. All of them were diagnosed of post-renal AKI and underwent emergent hospitalization. Evaluation of serum electrolytes, creatinine (Cr), blood urea nitrogen (BUN), complete blood count, and blood gas analysis were completed in each child both before they were admitted, and again after surgery. Bilateral externalized ureteral catheters were placed cystoscopically in each of these patients. The composition of collected calculi was analyzed by infrared spectrography. Results: Bilateral externalized ureteral catheters were placed successfully in all patients. There were no procedure-related complications. Two days after catheter placement, the levels of serum Cr and BUN had improved in all patients, and these levels were noted to be significantly lower than before catheterization (P < 0.001). Infrared spectrography demonstrated that the primary composition of all calculi collected was ceftriaxone. No recurrent AKI or renal deterioration was detected during the follow-up which ranged from 3 to 8 years. Conclusions: These results show that short-term external ureteral catheters can be effectively utilized in children with AKI caused by ceftriaxone-induced urolithiasis. We recommend this procedure as a viable replacement to indwelling stents in patients with bilateral ureteral stones.

Percutaneous Nephrolithotomy in Children: Analysis of Nationwide Hospitalizations and Short-Term Outcomes for the United States, 2001-2014

OBJECTIVE

To describe population-wide utilization rates and outcomes of percutaneous nephrolithotomy (PCNL) in the management of pediatric upper urinary tract calculi (UUTC).

PATIENTS AND METHODS

Patients <18 years with a diagnosis of UUTC, who underwent PCNL between 2001 and 2014 were identified from the National Inpatient Sample database. Annual PCNL rates, based on the at-risk population for each year, were estimated, and change in utilization rate was analyzed using negative binomial regression. Perioperative outcomes, hospital length of stay (LOS), and costs were determined; continuous and categorical variables were analyzed using nonparametric tests and Chi-squared tests, respectively. Trends tests and multivariable analyses (MVAs) were also performed where appropriate.

RESULTS

An estimated 3206 pediatric PCNL procedures were performed. Mean annual PCNL rate increased significantly relative to 2001 (incidence rate ratio = 1.40; 95% confidence interval 1.15-1.71, p = 0.001). Proportion of PCNL as a fraction of all inpatient surgical procedures for UUTC also significantly increased over time, from 15.7% in 2001 to 26.4% in 2014 (p < 0.0001). Complications overall occurred in 20.7% of cases, with a significantly rising rate over time period (p < 0.0001). Complication rates were similar across hospital types and geographic regions. Median hospitalization cost was significantly higher for the West than for each of the other regions (p < 0.05 in each case). Median LOS was also highest for the West (4 days vs 3 days for each of the other regions). In MVA, significant predictors of both increased LOS and costs included black race, comorbidities of hypertension, diabetes, coagulopathy and neurologic disease, hospitalization in the South, and presence of complications. Race, gender, comorbidities, and treatment year were among the predictors of complications.

CONCLUSIONS

PCNL utilization in the management of pediatric UUTC has significantly increased since 2001, with an associated increase in complication rates, although major complications were uncommon. Regional variations in costs and LOS were evident.

Systematic radiologic detection of kidney stones in Canadian children: a new era of asymptomatic stones?

INTRODUCTION

Asymptomatic, or incidental, pediatric kidney stones detected on abdominal imaging pose a clinical challenge as their significance and expected outcome are not well described.

OBJECTIVE

Our primary objective was to estimate the incidence of nephrolithiasis in pediatric patients undergoing abdominal ultrasound (US) or computerized tomography (CT), for all indications, in a pediatric tertiary care hospital. Our secondary objective was to determine the clinical outcome of these radiographically detected stones.

METHODS

All abdominal US or CT radiology reports for patients younger than 18 years between January 1, 2011, and December 31, 2016, were retrieved. Reports were automatically flagged using textual analysis if they contained one of the 32 keywords potentially indicating nephrolithiasis. Flagged reports, as well as 10% of unflagged reports, were reviewed to confirm the radiologist impression of presence or absence of stones. Patient and stone-related clinical data were extracted.

RESULTS

Two thousand four hundred forty-nine (5%) of 53 235 imaging reports cited at least one of the keywords. Manual review of flagged reports identified 498 studies having a radiologist impression of stones (244 unique patients). Stone incidence in children undergoing abdominal imaging more than doubled between 2011 and 2016. Medical record review found that 140 patients (57%) were symptomatic, while the other 104 patients (43%) were asymptomatic. Spontaneous resolution was greater (57% vs 34%) in asymptomatic patients compared to symptomatic patients. Asymptomatic patients were younger with a median age of 0.6 compared to 12.3 years. Asymptomatic and symptomatic stones were followed up for similar lengths of time (2.3 vs 2.0 years, p > 0.05) and had a similar number of follow-up USs (3.9 vs 4.6 studies, p > 0.05).

CONCLUSIONS

The incidence of radiologically identified stones in children undergoing abdominal imaging at our center increased over time. Asymptomatic stones follow a benign course with minimal need for intervention; however, they were detected almost as frequently as symptomatic stones. Asymptomatic stones may represent increased healthcare resource utilization due to similar follow-up compared to symptomatic stones. Further research regarding the optimal imaging intervals and long-term follow-up for asymptomatic stones is warranted.

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.

Pediatric calculi: cause, prevention and medical management

PURPOSE OF REVIEW

The incidence of pediatric nephrolithiasis is on the rise, with a significant related morbidity and a concomitant relevant increase in healthcare costs. The purpose of this review is to portray the current epidemiology and cause of renal stones in children, to provide a framework for appropriate clinical evaluation on an individual basis, and a guidance regarding treatment and prevention for the significant risk of lifelong recurrence and deriving complications.

RECENT FINDINGS

The early identification of modifiable risk factors and other abnormalities is essential, to prevent related morbidity, the onset of chronic kidney disease, and the associated increased risk of developing other diseases. The implementation of risk reduction strategies, including dietary modifications and targeted pharmacological therapies, will significantly influence stone recurrences and preserve renal function.

SUMMARY

Future research is desirable, with the aim to strengthen personalized conservative management of pediatric nephrolithiasis as first-line treatment.

Impact of the Image Gently® Campaign on Computerized Tomography Use for Evaluation of Pediatric Nephrolithiasis

PURPOSE

The Image Gently® campaign was launched by several radiological societies in 2007 to promote safe imaging in children. A goal of the campaign was to reduce ionizing radiation exposure in children. Given the recurrent nature of kidney stones, affected children are at risk for unnecessary ionizing radiation exposure from computerized tomography. We sought to determine whether the Image Gently campaign led to a decrease in the use of computerized tomography for evaluating children with nephrolithiasis. We hypothesized that the campaign was the primary cause of a reduction in the use of computerized tomography.

MATERIALS AND METHODS

We analyzed medical claims data from 2001 to 2015 identifying children with nephrolithiasis covered by the same commercial insurance provider. Using a difference in differences design, we estimated changes in computerized tomography use after the campaign started among patients less than 18 years old compared to a control group age 18 years or older with nephrolithiasis.

RESULTS

We identified 12,734 children and 787,720 adults diagnosed with nephrolithiasis. Before 2007 quarterly rates of computerized tomography use during a stone episode (per 1,000 patients) were increasing at a parallel rate in children and adults (5.1 in children vs 7.2 in adults, p = 0.123). After the Image Gently campaign started the use of computerized tomography decreased in both groups but at a slightly higher rate in adults (difference in differences 2.96, 95% CI 0.00 to 5.91, p = 0.050).

CONCLUSIONS

Although there has been a reduction in the use of computerized tomography among children with nephrolithiasis, given a similar trend seen in adults this change cannot be primarily attributed to the Image Gently campaign.

A randomized trial of a multi-level intervention to increase water access and appeal in community recreation centers

INTRODUCTION

Improving children's tap water intake and reducing sugar-sweetened beverage (SSB) consumption is beneficial for health and health equity, particularly in low-income communities and communities of color. Existing community level interventions to improve the intake of tap water have predominantly occurred in schools and have focused on promoting water consumption in cafeterias during lunch or snack periods.

METHODS

The "Hydrate Philly" intervention was developed to target multiple environmental and social factors to improve tap water consumption in community recreation centers in low-income communities: replacing old and unappealing water fountains with appealing water-bottle-filling "hydration stations", conducting water safety testing and publicizing results, disseminating reusable water bottles, promoting tap water, and discouraging SSB consumption. Efficacy of the intervention will be tested through a group-randomized controlled trial (n = 28 centers) of the intervention's impact on center-level water fountain/station use as measured by flow meters during a youth summer camp program primarily for children aged 6-12 years. Intervention impact on the primary outcome (use of drinking water sources) will be examined with a difference-in-differences approach using an ordinary least squares regression model for analysis at the center level. Secondary outcomes include SSBs brought to summer camp, reusable and single-use bottled water use, program trash, and recreation center staff SSB consumption.

DISCUSSION

Multilevel approaches are needed to increase tap water intake and decrease SSB consumption among low-income and minority youth beyond school and meal settings. The current study describes the Hydrate Philly intervention, the study design, and baseline characteristics of recreation centers participating in the study. ClinicalTrials.gov Registration: #NCT03637465.

Biochemical metabolic levels and vitamin D receptor FokⅠ gene polymorphisms in Uyghur children with urolithiasis

Because of lacking studies of urolithiasis in children, we detected the biochemical metabolic levels and FokⅠ polymorphisms in the vitamin D receptor (VDR) in Uyghur children with urolithiasis, and evaluated the associations of biochemical metabolic levels with FokⅠ genotypes. We included 142 Uyghur children (108 males) under age 14 years with a diagnosis of urolithiasis and 238 Uyghur children (154 males) under age 14 years without a history of urolithiasis as controls. Baseline information and data for serum and urine parameters were obtained from medical records. PCR-restriction fragment length polymorphism (PCR-RFLP) was used to analyze the VDR FokⅠ polymorphisms. In univariate analyses adjusting for age and sex, carbon dioxide combining power (CO2CP) (odds ratio [OR] = 1.13, 95% confidence interval [CI]: 1.07-1.19), serum magnesium (Mg) (OR = 1.27, 95% CI: 1.03-1.56) and serum chlorine (Cl) (OR = 0.93, 95% CI: 0.88-0.97) were related to Uyghur children urolithiasis risk. A multiple logistic regression model showed CO2CP (OR = 1.17, 95% CI: 1.09-1.26), levels of uric acid (OR = 1.01, 95% CI: 1.00-1.01) and serum sodium (Na) (OR = 0.90, 95% CI: 0.82-0.99) were associated with pediatric urolithiasis. The risk of urolithiasis was increased with the F versus f allele overall (OR = 1.42; 95% CI: 1.01-2.00) and for males (OR = 1.52, 95% CI: 1.02-2.27). However, metabolic levels did not differ by FokⅠ genotypes. In our population, CO2CP and levels of uric acid and serum Na as well as polymorphism of the F allele of the VDR FokⅠ may provide important clues to evaluate the risk of urolithiasis in Uyghur children.

Mini-percutaneous nephrolithotomy for pediatric complex renal calculus disease: one-stage or two-stage?

OBJECTIVES

To compare two different treatment strategies, one-stage and two-stage multi-tract mini-percutaneous nephrolithotomy (mt-mPCNL), for pediatric complex renal calculus disease.

METHODS

Between the period of July 2016 and July 2018, a total of 36 children aged 15 years and younger, with complex renal calculi disease, who underwent total ultrasound-guided mt-mPCNL by a single experienced urologist were enrolled in our study. All patients were assigned either to Group 1 (n = 18) who received one-stage mt-mPCNL or Group 2 (n = 18) who received planned two-stage mt-mPCNL.

RESULTS

The demographic data were comparable between the two groups. There were no serious complications (Modified Clavien Grade ≥ III) observed in either group. The stone -free rate (SFR), operation time, postoperative creatinine increase, and perioperative complication rates were similar in both groups (P = 0.603, 0.818, 0.161, and 0.402, respectively). The postoperative hospital stay (5.8 days vs. 7.4 days) and cost (17373.3 CNY vs. 23717.1 CNY) were statistically less in Group 1. Group 2 had significantly less total estimated blood loss (70.6 ml vs. 130.0 ml, P < 0.001). The operation time of two cases in Group 1 with perioperative sepsis or systemic inflammatory response syndrome (SIRS) was more than two hours.

CONCLUSIONS

Our preliminary results indicated that both one-stage and two-stage mt-mPCNL were safe and effective for pediatric complex renal calculi. Two-stage mt-mPCNL could significantly reduce blood loss; while one-stage mt-mPCNL could significantly decrease the length and costs of hospitalization. We also suggest that the planned two-stage mt-mPCNL should be applied in children with estimated operation time more than two hours.

CLINICAL-EPIDEMIOLOGICAL PROFILE OF 106 PEDIATRIC PACIENTS WITH UROLITHIASIS IN RIO DE JANEIRO, BRAZIL

Objective:

To describe the frequency, clinical profile and treatment of patients with urolithiasis in the Pediatric Nephrology Department of a public state hospital in Rio de Janeiro, Brazil.

Methods:

Retrospective study. Data from pediatric patients (age: 1 month - 18 years) with urolithiasis admitted between January/2012 and December/2014 were reviewed from hospital charts. The studied variables were: demographic and anthropometric data, clinical status, family history of urolithiasis, urinary tract infection and use of lithogenic drugs, diagnostic procedures, associated abnormalities, metabolic disorders, treatment and recurrence.

Results:

The frequency of urolithiasis was 13.6%. Main characteristics of the patients: male gender, white race, eutrophy, aged between 5 and 10 years, family history of urolithiasis, previous urinary infection and spontaneous stone passage. Abdominal and flank pain and macroscopic hematuria were the most common complaints. The most frequent metabolic disorders were hypercalciuria, hyperuricosuria and hypocitraturia. Hypocitraturia was associated with previous urinary infection (p=0.004). Abdomen/urinary tract ultrasonography was the most commonly used diagnostic test. Hydronephrosis occurred in 54.4% of the cases, 81.1% of the stones were in the kidneys, and bilateral stones were associated to a family history of urolithiasis (p=0.030). Recurrence rate was 29.3% (most patients had a metabolic disorder). In 12.3%, the patients underwent lithotripsy, 24.5% were surgically treated (mainly pyelolithotomy), and only 7.6% had their stones analyzed (calcium oxalate was the main finding in the examined stones).

Conclusions:

The frequency of urolithiasis in these pediatric patients was similar to that reported by the literature. A metabolic evaluation is required and the composition of stones should be better evaluated.

The ability of a limited metabolic assessment to identify pediatric stone formers with metabolic abnormalities

INTRODUCTION

American Urological Association guidelines recommend a urinary metabolic evaluation after the first stone event in all pediatric stone patients. Prior studies identified hypercalciuria and urine hypovolemia as the most common abnormalities in children with urolithiasis. Recent data suggest that hypocitraturia is most prevalent. It was hypothesized that a limited evaluation would detect the majority of clinically significant metabolic abnormalities in pediatric stone formers.

MATERIAL AND METHODS

A retrospective analysis of all children (<18 years of age) with renal/ureteral calculi evaluated at the study institution from 2005 to 2015 was performed. Children with ≥ one 24-h urinary metabolic profile after a clinical visit for renal/ureteral calculi were included. Those with bladder stones and those with undercollection or overcollection or missing urinary creatinine were excluded. Demographics and data from the first urinary metabolic profile and stone analyses were collected. The sensitivity, specificity, and positive and negative predictive value (NPV) of a limited urinary metabolic evaluation consisting of four parameters (24-h calcium, citrate, and oxalate and low urinary volume) were compared to a complete urinary metabolic profile. The number and type of metabolic abnormalities that would have been missed with this limited evaluation weredetermined.

RESULTS

Of 410 patients, 21 were excluded for age ≥18 years, 13 for bladder stones, 248 for overcollections, 38 for undercollections, and 10 for missing creatinine. This left 80 patients for inclusion: median age 11.4 years, 60% female, and 96.3% white. Of the entire cohort, 69.6% had hypocitraturia, 52.5% had low urine volume, and 22.5% had hypercalciuria. Sensitivity was 87.5%. Specificity could not be calculated because no patients had a normal complete metabolic evaluation. The NPV was zero, and the positive predictive value was 100%, but these are artifacts resulting from the absence of patients with a normal complete metabolic evaluation. Of the 80 patients, 10 had at least one abnormality missed by a limited metabolic evaluation (Table 1). The missed abnormalities were high pH (n = 6), abnormal 24-h phosphorus (low in 1 patient and high in 1 patient), low 24-h magnesium (n = 3), low 24-h potassium (n = 3), and high 24-h sodium (n = 4).

DISCUSSION

A limited urinary metabolic evaluation would have detected the vast majority of clinically significant metabolic abnormalities in the study sample. Approximately two-thirds of the study patients submitted inadequate 24-h urine specimens.

CONCLUSIONS

A simplified approach to metabolic evaluation in first-time stone formers with a stone analysis available was proposed. This streamlined approach could simplify the metabolic evaluation and reduce health care costs.

Influence of BMI in nephrolithiasis in an Appalachian pediatric population: A single-center experience

INTRODUCTION

The prevalence of pediatric nephrolithiasis has increased significantly in the past 20 years. Metabolic abnormalities predisposing adults to nephrolithiasis in obese patients include increased urinary sodium and uric acid excretion as well as low urine pH; however, limited data are available in the pediatric population.

OBJECTIVE

The aim was to investigate whether obese pediatric patients presenting with nephrolithiasis have a unique metabolic profile similar to reported findings in obese adults with nephrolithiasis.

STUDY DESIGN

A retrospective chart review was performed in children aged 1-18 years seen at Kentucky Children's Hospital between 2010 and 2016. Inclusion criteria included all patients with documented stones confirmed by ultrasonography or computed tomography.

RESULTS

A total of 111 patient charts were reviewed in the study with a mean age of 11.8 ± 4.2 years. Seventy patients (63%) had a normal BMI and 41 patients (37%) were considered overweight/obese. There was no statistically significant relationship between BMI and stone recurrence. Obese patients had significantly decreased levels of urinary citrate, oxalate, magnesium, and potassium with significant elevations of urinary urea nitrogen, ammonia, and low urine pH compared with normal weight patients (Summary Figure).

DISCUSSION

Several groups have reported on metabolic findings within obese and non-obese pediatric patients. A Turkish study reported increased oxalate excretion and hypocitraturia in obese patients while a Korean study also reported increased rates of hypocitraturia in recurrent stone formers. Similar to these studies, we did find significant differences in citrate within our study population; however, we found significantly lower levels of urinary oxalate in obese patients. The majority of these studies do not report an association with BMI and urine pH although this has been reported in the adult population and our findings support an inverse relationship between body mass index (BMI) and pH. Our group found a higher level of calcium phosphate stones, supporting of Eisner's findings that high BMI is associated with increased supersaturation of calcium phosphate. Limitations of our study include being a single center and retrospective in nature.

CONCLUSION

Our study demonstrates differences in types of stones and urinary metabolites in an obese pediatric population suggestive of different metabolic profiles contributing to stone disease. We report similar association between BMI and urine pH, urinary potassium, and citrate. This study confirmed our primary hypothesis that obese pediatric patients would have a different urinary mineral profile as evidenced by lower levels of citrate and potassium and low urine pH; however, obese patients did not exhibit significantly elevated urinary sodium and uric acid when normalized to weight, as described in the adult population. Our study did not confirm our secondary hypothesis that stone composition would be associated with BMI status or stone recurrence.

Renal stone composition does not affect the outcome of percutaneous nephrolithotomy in children

PURPOSE

We sought to investigate the association between renal stone composition and percutaneous nephrolithotomy outcomes in pediatric patients and define the characterization of the stone composition.

METHODS

The data of 1157 children who underwent percutaneous nephrolithotomy between 1991 and 2012 were retrieved from the multicenter database of the Turkish Pediatric Urology Society. The study population comprised 359 children (160 girls, 199 boys) with stone analyses. Patients were divided into five groups according to the stone composition [group 1: calcium oxalate; group 2: calcium phosphate; group 3: infection stones (magnesium ammonium phosphate, ammonium urate); group 4: cystine; group 5: uric acid, xanthine stones].

RESULTS

Patient characteristics, perioperative, postoperative, and stone characteristics were compared considering the stone composition. There were no significant differences between the groups concerning age, sex, side involved, preoperative hematocrit levels, and solitary renal unit. Patients with cystine stones were more likely to have a history of stone treatment. Groups 2 and 5 had mostly solitary stones. However, group 3 had staghorn stone more often, and group 4 frequently had multiple stones. Overall stone-free rate (79.4%) was similar among the groups. Although stone composition was related to blood transfusion and prolonged operative and fluoroscopy screening times on univariate analysis, it was not a significant predictor of them on multivariate analysis.

CONCLUSIONS

Stone composition was not a predictor of outcomes of pediatric percutaneous nephrolithotomy. However, cystine and infection stones, which are larger and filled multiple calyxes due to the nature of stone forming, were more challenging cases that need multiple tracts.