Pediatric urolithiasis: experience from a tertiary referral center

Kidney Stones in Children: Causes, Consequences, and Concerns

The prevalence of kidney stones (nephrolithiasis) in children has been steadily rising in the last two decades. The commonly reported environmental causes for this rise in the prevalence of nephrolithiasis include obesity, increased intake of fructose-containing energy drinks, increased sodium content in junk foods, decrease in water intake as well as poor oral calcium intake, and increasing usage of antibiotics that deplete the oxalate-metabolizing bacteria in the gut. Increased detection of monogenic causes of nephrolithiasis is being facilitated with the easy availability of next-generation sequencing (NGS). These include primary hyperoxaluria types 1, 2 and 3, hypercalciuria (including monogenic and idiopathic types), hyperuricosuria (including Lesch-Nyhan syndrome, and urate transporter defects, etc.), cystinuria, hereditary xanthinurias, adenine phosphoribosyl transferase (APRT) deficiency (causing 2, 8 dihydroxyadenine stones) etc. The evaluation of pediatric nephrolithiasis includes a comprehensive history taking, examination, basic imaging using renal ultrasound, metabolic evaluation and genetic testing. The recurrence risk for kidney stone occurrence in children is high, placing them at risk for severe morbidities including renal colic, urinary tract infections, acute kidney injury and chronic kidney disease. The management of nephrolithiasis in children necessitates a multidisciplinary approach involving pediatricians, pediatric nephrologists, urologists, dietitians, and nurses.  While medical advancements offer effective treatments for kidney stones in children, prioritizing prevention and accurate diagnosis with the usage of appropriate genetic and metabolic work-up remains crucial for optimal management.

Urinary stone disease in Syrian children

BACKGROUND

Pediatric urinary stone disease (USD) is a costly medical problem. This study aims to assess the clinical characteristics and outcomes of common and rare causes of pediatric USD.

METHODS

A retrospective descriptive cohort study included all children < 13 years of age with confirmed USD admitted to the Children's University Hospital in Damascus, Syria, from January 2013 to December 2019. The study sample was divided into two groups based on etiologies: common and rare causes groups.

RESULTS

We evaluated 235 patients; 147 of them were males, and the male-to-female ratio was 1.7:1. The common causes group consisted of 203 patients (mean age 3.52 ± 3.66 years) and mainly included metabolic disorders (45.5%) and anatomical abnormalities (22.3%), while the rare causes group included 32 cases (mean age 4.93 ± 4.08 years), 12 patients with uric acid stones (37.5%), 7 patients with cystinuria (21.9%), and primary hyperoxaluria in 5 patients (15.6%). In addition, 39.6% of study patients were born to consanguineous marriages. Sixty-two patients developed AKI, and eleven patients had chronic kidney disease (CKD). Patients with rare causes were more likely to have AKI, CKD, bilateral stones, and recurrent stones (P-value < 0.05). Stone analysis was performed on 83 patients, and the main stone types were calcium oxalate (34.9%), uric acid (14.4%), and struvite stones (12%). Surgery was the most performed treatment in 101 patients (56.7%).

CONCLUSION

Patients with rare causes of pediatric USD are at a higher risk for severe complications and require early diagnosis and management. The high rate of uric acid stones in our society requires further evaluation for possible underlying causes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Primary versus deferred ureteroscopy for the management of obstructive anuria secondary to ureteric urolithiasis in children: a prospective randomized study

To compare the role of primary and deferred ureteroscopy (URS) in the management of obstructive anuria secondary to ureteric urolithiasis in pediatric patients. This prospective randomized study included 120 children aged ≤ 12 years who presented with obstructive anuria secondary to ureteric urolithiasis between March 2019 and January 2021. The children were subdivided into group A, which included children who had undergone primary URS without pre-stenting, and group B, which included children who had undergone URS after ureteric stenting. All children were clinically compensated and sepsis-free. Patients with underlying urological structural abnormalities were excluded. The operative time, improvement of renal functions, stone-free rate, and complications were compared between the two groups. At the 1-month follow-up, urine analysis; kidney, ureter, and bladder radiography; and ultrasonography were performed. The patient characteristics of both groups did not show any significant difference. Primary URS had failed in ten children (16.6%) in group A. Moreover, failure of stenting was noted in six patients (11%) in group B. The mean operative time for group B was significantly lower than that for group A (p ≤ 0.001). The stone-free rate was significantly higher in group B (p ≤ 0.001). The rate of overall complications was higher in group A. Deferred URS is preferable over primary URS in the management of obstructive anuria secondary to ureteric urolithiasis". In children because of the lower need for ureteric dilatation, higher stone- free rate, shorter procedure time, and lower complication rate.

Diet, Fluid Intake, Urine Output and Urinary Sodium/Potassium Ratios in Children With Urolithiasis

We performed a cross-sectional study on 25 children (17 boys) with urolithiasis with normal glomerular functions at a tertiary care teaching hospital between March, 2018 to March, 2019. Dietary assessment showed that caloric intake was below recommended dietary allowance (RDA) in 68% patients while the median protein intake was 34.3% more. The fluid intake was below the recommended standards in 56%, and 48% of the children had urine output below 1.5 mL/kg/hour. The urinary sodium was elevated in 96% of the children, urinary potassium was low in 40%, and hypercalciuria was seen in 28%. While metabolic causes predominate in childhood urolithiasis, other factors like dietary changes, liberal fluid and low sodium intake are advised for prevention of recurrences as they have a contributory role too.

Metabolic and Clinical Characteristics of Children with Urolithiasis from Southern India

OBJECTIVE

To study the etiological profile and patterns of clinical presentations of urolithiasis (UL) in children.

METHODS

This observational study included patients <18 y with UL, who were referred to the pediatric nephrology clinic. Clinical features, family history, consanguinity and estimated glomerular filtration rate (eGFR) at presentation and follow-up were recorded. The children were evaluated using relevant blood and urine investigations.

RESULTS

A total of 72 children with UL were evaluated for the study. The etiology of UL (n = 72) included hyperoxaluria (n = 25; 34.7%), idiopathic hypercalciuria (n = 21; 29.2%), idiopathic hyperuricosuria (n = 3; 4.2%), cystinuria (n = 3; 4.2%), urate transporter defect (n = 2; 2.8%) and mixed stones (predominant component calcium oxalate) (n = 9; 12.5%). No etiology was detected in 4 cases (5.5%). Common presenting complaints included flank pain (n = 41; 56.7%), hematuria (n = 29; 40.3%), urinary tract infection (UTI) (n = 29; 40.3%) and vomiting (n = 11; 15.3%). The median age of presentation was 60 (36, 96) mo. Family history and consanguinity were present in 30 cases (41.7%) and 28 cases (38.9%) respectively. Stone analysis was done in 20 cases, of which 9 cases were mixed stones (predominant calcium oxalate) and 6 were calcium oxalate stones.

CONCLUSIONS

Among children with urolithiasis, hyperoxaluria, idiopathic hypercalciuria, idiopathic hyperuricosuria, and cystinuria were the predominant identifiable entities, together accounting for 72% of cases; and renal colic, hematuria and UTI were the commonest clinical complaints.

Extracorporeal shock wave lithotripsy in Indian children: Predictors of outcome and validation of pre-treatment nomograms

BACKGROUND

Although multiple variables have been shown to affect outcomes in pediatric lithotripsy (ESWL), there is no consensus on the same. Nomograms combine multiple variables and provide an objective prediction of outcomes. Two nomograms have been previously described and validated in two studies from the same geographical area. External validation in multiple settings is needed, as a nomogram's performance may vary with time, geographical area and clinical scenario.

OBJECTIVES

This study aimed to identify variables influencing pediatric ESWL outcomes, validate published nomograms and describe the clinical and metabolic profile of Indian children treated with ESWL.

DESIGN

This retrospective cohort study included all children who underwent ESWL from 2002 to 2019 at a single centre. ESWL was performed under general anaesthesia. Mid and lower ureteric calculi were treated in prone and the rest in supine position. 1500-2000 shocks were delivered at a voltage of 12-16 kV. Data pertaining to patient characteristics, metabolic evaluation, imaging, ESWL details and post-procedure outcomes were obtained from the hospital information system and these variables, along with Onal and Doğan scores, were correlated with stone clearance. Cut-offs for Onal and Doğan scores were determined using receiver operator characteristic (ROC) curve analysis and compared with area under the curve (AUC). Complications, ancillary procedures and metabolic abnormalities were recorded.

RESULTS

A total of 66 children (76 renal units) were included. Mean age was 5.5 years (Range 6 months-14 years) and median stone size, 12 mm (IQR 9, 15.25). Average treatment sessions were 1.8 ± 0.99. Median shocks in the stone-free group and those who failed treatment were 1750 (IQR 1500, 3000) and 3250 (IQR 1750, 4750) respectively. The remaining variables are depicted in Table 1. The stone free rate was 63.2%. Fragments <4 mm were seen in 19 (25%). Efficacy Quotient was 40. The AUC for Doğan nomogram (cut-off <199.5) was 0.761 while that for Onal nomogram (cut-off <2.5) was 0.762 and 0.771 after one and three shocks respectively. On multivariate analysis, age, multiple calculi, Onal and Doğan scores were predictive of clearance. Doğan score had higher specificity. Complications were seen in 16 (21%) and ancillary procedures needed in 7 (9.2%). Metabolic abnormalities were seen in 84.8%, the commonest being hyperoxaluria. Mixed stones were most frequent.

CONCLUSIONS

Lithotripsy in children is safe and effective. Older age, presence of multiple calculi, higher Onal and Doğan scores are predictive of treatment failure.

Efficacy and Safety of Supracostal Access for Mini Percutaneous Nephrolithotomy in Pediatric Patients

OBJECTIVE

To evaluate the efficacy and safety of supracostal percutaneous nephrolithotomy (PCNL) through the 11th intercostal space and compare it with subcostal PCNL in children with renal calculi.

MATERIALS AND METHODS

Children with renal calculi who underwent PCNL between January 2010 and December 2017 were divided into 2 groups: supracostal PCNL (group 1) and subcostal PCNL (group 2). Stone location, stone burden, location of the access points, operative time, postoperative visual pain score, success rate, hospital stay, and complications according to the modified Clavien classification were compared. Comparison of medians was done using Mann Whitney U test and the means were compared using t test.

RESULTS

Group 1 had 50 patients while group 2 had 60 patients. The stone-free rate was 84.0% and 85.0% in groups 1 and 2, respectively after 1 session of PCNL (P = .885). After auxiliary procedures, it increased to 96.0% and 96.6%, respectively (P = .852). The mean fall in hematocrit was 0.9% in group 1 and 1.5% in group 2 (P = .11) whereas the median pain score was 4 in group 1 and 3 in group 2 (P = .37). In all, 54 complications were recorded the commonest among which were grade I (81.5%). Twenty-nine complications were observed in group 1 while 25 complications were observed in group 2 (P = .088). One patient developed nephropleural fistula while another patient developed hydropneumothorax. Both belonged to group 1.

CONCLUSION

Supracostal access for PCNL is an effective and safe alternative to subcostal access for children with renal calculi in terms of stone-free rate and complications.

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.

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.

Management of Pediatric Urolithiasis Using a Combination of Laparoscopic Lithotomy and Pyeloscopy

BACKGROUND

Minimally invasive procedures have become the standard option for treatment of urinary stones; the use of more invasive techniques is not a common practice currently. This emergent technology is not always available and laparoscopy is the alternative option. There are few reports of laparoscopic management for urinary lithiasis in pediatric patients. This study is about the use of laparoscopic surgery combined with pyeloscopy as a feasible first-line treatment for pediatric urolithiasis in renal and proximal ureteral locations.

PATIENTS AND METHODS

We reviewed the records of 14 patients with renal and proximal ureteral stones who underwent laparoscopic pyelolithotomy and pyeloscopy in a period from January 2011 to July 2016. The outcome measures were needed for auxiliary procedures, treatment success, and complication rates.

RESULTS

A total of 16 procedures were carried out in 14 patients, 15 transperitoneal and 1 retroperitoneal laparoscopic pyelolithotomies were done. It was necessary to perform upper ureterolithotomies to remove ureteral stones in 2 cases. The holmium laser and/or pneumatic lithotripter were used to fragment staghorn calculi. Some of the complications were blood transfusion in 12.5% and self-limited urinary leak in 18.7% of the patients. The success rate after undergoing one procedure was 92.8%.

CONCLUSIONS

Transperitoneal or retroperitoneal laparoscopic lithotomy is a safe and feasible procedure for the treatment of pediatric urolithiasis. It can be an alternative to shock-wave lithotripsy and percutaneous nephrolithotomy when these are not feasible or possible.

Association of Inflammatory Bowel Disease and Urolithiasis in Hospitalized Pediatric Patients

BACKGROUND

Urolithiasis is rare in pediatric patients. All patients with inflammatory bowel disease (IBD) have an increased risk of urolithiasis, but this risk is poorly quantified in children. The objective of this study is to evaluate the association of IBD with urolithiasis, assess surgical outcomes, and analyze the financial burden for children hospitalized with urolithiasis and comorbid IBD.

METHODS

The triennial Healthcare Cost and Utilization Project Kids' Inpatient Database for years 1997 to 2012 was used to evaluate the association between urolithiasis and IBD in hospitalized, nonpregnant children ages 5 to 20 years old. Billing codes were used to define conditions. Logistic regression analysis quantified the association between IBD types and urolithiasis. Length of hospital stay, costs, procedures, and complications were compared between urolithiasis patients with and without IBD.

RESULTS

Among 8,828,522 hospital admissions, we identified 36,771 admissions with a primary diagnosis of urolithiasis. Of these cases, 230 were associated with Crohn's disease (odds ratios, 1.99; 95% confidence interval, 1.74-2.27) and 102 with ulcerative colitis (odds ratio, 1.63; 95% confidence interval, 1.34-1.99). Urolithiasis patients with ulcerative colitis, but not Crohn's disease, had significantly increased length of stay and costs. Patients with either IBD had a decreased number of urologic procedures.

CONCLUSIONS

The diagnosis of urolithiasis in pediatric patients is associated with IBD, and those with ulcerative colitis have longer hospital stays and greater costs. Patients with IBD have fewer urologic procedures associated with their urolithiasis diagnosis.

Metabolic features and renal outcomes of urolithiasis in children

AIM

The incidence of pediatric urolithiasis has increased over the last century because of dietary changes, metabolic abnormalities, climate change, and genitourinary abnormalities. Data on pediatric urolithiasis in non-endemic countries are limited. The aim of this study was to evaluate the clinical findings and metabolic etiology of urolithiasis in Korean children.

MATERIAL AND METHODS

The medical records of 73 Korean children who were newly diagnosed with urolithiasis from January 2010 to December 2013 were retrospectively analyzed. Evaluation of metabolic risk factors, including hypercalciuria, hyperuricosuria, hypomagnesuria, hyperoxaluria, and hypocitraturia, required analysis of 24-h urine specimens or, alternatively, for infants and toddlers, the solute-creatinine ratio in spot urine.

RESULTS

The male-to-female ratio of the included patients was 1.3:1. The median age at diagnosis was 10.1 years, and the patients were divided into two age groups with pre-school-age children (n = 27, 37.0%) and school-age children (n = 46, 63.0%). While flank pain was more common in school-age children, incidentally detected or urinary tract infection (UTI)-associated urolithiasis was more common in pre-school-age children. Eight patients (11.0%) had renal function deterioration associated with urolithiasis, and three patients (4.1%) progressed to chronic kidney disease. Metabolic abnormalities according to urine chemistry were found in 30 patients (41.1%), including hypercalciuria in 21.9%, hyperuricosuria in 11.0%, hypomagnesuria in 4.1%, hyperoxaluria in 1.4%, hypocitraturia in 1.4%, and cystinuria in 1.4%.

CONCLUSION

We suggest that school-age children with renal colic and pre-school-age children with UTI should be evaluated for urolithiasis. Additionally, the evaluation for metabolic risk factors is important in order to prevent recurrence and renal insufficiency.

Medical expulsive treatment in pediatric urolithiasis

The frequency of stone disease in childhood ranges between 0.1-5 percent. Stone disease occurs as a result of enviromental, metabolic, anatomical, infectious and nutritional factors. Percutaneous nephrolitotomy, uretherorenoscopy, laparoscopic surgery, open surgery and extracorporeal shock wave lithothripsy are treatment alternatives for stone disease during childhood. However, these methods are not completely innocent. Some complications may occur after these procedures. These procedures are generally not cost- effective. Even invasive procedures have high success rates, so medical expulsive treatment modalities have become an alternative for a group of patients. Nonsteroidal anti- inflammatory drugs, antimuscarinic drugs, phospodiesterase type 5 inhibitors, steroids, calcium channel blockers and alpha blockers are treatment alterneatives used for this modality in the literature. The drug is chosen according to the location, size, and composition of the stone, recent technology, cost, surgeon's experience and surgeon's and the parents' preferences. In this review article the following topics will be discussed such as "Why medical expulsive treatment is needed during childhood? Which drug should be chosen for which stone type? How long should a treatment of urolithiasis last?

Ureteroscopy for Paediatric Renal Tract Stones - Outcomes from a Tertiary European Centre

Aims: The use of ureteroscopy in treating paediatric stone disease has risen in recent years. We retrospectively reviewed the results of ureteroscopic stone management for our regional paediatric stone service. Material and Methods: Between April 2010 and October 2013, consecutive patients undergoing ureteroscopy and stone fragmentation were identified. Data were recorded from electronic records for patient demographics, pre-operative assessment, stone characteristics, and intra- and post-operative complications. Results: Twenty-one patients (mean age 8.6 years; range: 1.4-16) had 32 procedures in our series (13 males and 8 females). Five (24%) had a metabolic abnormality and 8 (38%) had an anatomical abnormality. The mean initial stone size was 9.6 mm (range: 5-20) and 10 were left sided. Of the 32 procedures, 18 (56%) had a pre-operative stent. A positive pre-operative urine culture was seen in 4 (13%). CT was used in 6 (19%) with the rest having a combination of USS and/or plain KUB. Of these 21 patients, 13 (62%) were stone free after the first procedure, 17 (81%) after a second and 20 (95%) after a third (mean 1.5 procedures/patient). One patient with a 6-mm residual fragment chose to have surveillance. Eighteen (50%) had post-operative stent insertion. The mean length of stay was 1.5 days (range: 0-5). A minor complication (Clavien 1) was observed in 1 patient. No other complications were recorded. Conclusions: Ureteroscopy for stone disease in children is feasible with a low complication rate and high stone-free rate.

Ureteroscopy for treatment of upper urinary tract stones in children: technical considerations

The incidence of pediatric urolithiasis is increasing. While many smaller stones may pass spontaneously, surgical therapy is sometimes warranted. Surgical options include shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, and open surgery. Ureteroscopy represents a minimally invasive approach, and it is increasingly being used to treat pediatric upper tract calculi. Ureteroscopy is performed under anesthesia and fluoroscopic guidance, with basket extraction or lithotripsy of the calculi. Technical considerations include active or passive ureteral dilatation, the use of ureteral access sheaths for larger stone burdens, and post-operative stent placement. The current pediatric literature suggests high success rates (equal to or surpassing shock wave lithotripsy) and low complication rates. However, concerns remain regarding feasibility in patients with variant anatomies and risk due to intra-operative radiation exposure.

Underuse of 24-hour urine collection among children with incident urinary stones: a quality-of-care concern?

OBJECTIVE

To determine the prevalence of 24-hour urine collection among first-time pediatric stone formers and investigate factors associated with its use.

MATERIALS AND METHODS

Using data from the MarketScan Commercial Claims and Encounters Database (2002-2006), children presenting to the emergency department with an incident episode of upper urinary tract stone disease were identified through a diagnosis code-based algorithm. The number of patients performing a 24-hour urine collection within 6 months of this encounter was calculated. Temporal trends in the prevalence of use were assessed. We fitted multivariate logistic regression models to examine factors associated with testing.

RESULTS

In total, 1848 children presented with an incident upper tract stone, of which 12.0% submitted a 24-hour urine collection. This percentage remained stable over the study period. Testing was more common among younger patients (P <.001) and those who visited urologists (P <.001) or nephrologists (P <.001). The odds of testing were nearly 4-fold or 7-fold higher if the patient saw a urologist (odds ratio, 3.99; 95% confidence interval, 2.83-5.62) or a nephrologist (odds ratio, 7.00; 95% confidence interval, 3.95-12.41), respectively.

CONCLUSION

Despite rates of stone recurrence, 24-hour urine collection appears to be underused among children. Efforts to increase its use are therefore likely to benefit pediatric patients with urinary stone disease.