Clinical and metabolic features of urolithiasis and microlithiasis in children

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Risk factors for recurrence in pediatric urinary stone disease

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Increased risk of nephrolithiasis: an emerging issue in children with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

PURPOSE

To investigate the incidence of nephrolithiasis in a cohort of children with congenital adrenal hyperplasia (CAH), and to study if there is an association with the metabolic control of the disease.

METHODS

This study was designed as a multicenter 1 year-prospective study involving 52 subjects (35 males) with confirmed molecular diagnosis of CAH due to 21-hydroxylase deficiency (21-OHD). Each patient was evaluated at three different time-points: T0, T1 (+6 months of follow-up), T2 (+12 months of follow up). At each follow up visit, auxological data were collected, and adrenocorticotrophic hormone (ACTH), 17-hydroxyprogesterone (17-OHP), Δ4-androstenedione, dehydroepiandrosterone sulfate (DHEAS) serum levels, and urinary excretion of creatinine, calcium, oxalate and citrate were assayed. Moreover, a renal ultrasound was performed.

RESULTS

The incidence of nephrolithiasis, assessed by ultrasound was 17.3% at T0, 13.5% at T1 and 11.5% at T2. At T0, one subject showed nephrocalcinosis. In the study population, a statistically significant difference was found for 17-OHP [T0: 11.1 (3.0-25.1) ng/mL; T1: 7.1 (1.8-19.9) ng/mL; T2: 5.9 (2.0-20.0) ng/mL, p < 0.005], and Δ4-androstenedione [T0: 0.9 (0.3-2.5) ng/mL; T1: 0.3 (0.3-1.1) ng/mL; T2: 0.5 (0.3-1.5) ng/mL, p < 0.005] which both decreased over the follow up time. No statistically significant difference among metabolic markers was found in the group of the subjects with nephrolithiasis, even if 17-OHP, DHEAS and Δ4-androstenedione levels showed a tendency towards a reduction from T0 to T2. Principal component analysis (PCA) was performed to study possible hidden patterns of associations/correlations between variables, and to assess the trend of them during the time. PCA revealed a decrease in the amount of the variables 17-OHP, Δ4-androstenedione, and ACTH that occurred during follow-up, which was also observed in subjects showing nephrolithiasis.

CONCLUSIONS

our data demonstrated that children affected with 21-OHD can be at risk of developing nephrolithiasis. Additional studies are needed to clarify the pathogenesis and other possible risk factors for this condition, and to establish if regular screening of kidney ultrasound in these patients can be indicated.

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

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

Novel compound heterozygous pathogenic variants in the SLC3A1 gene in a Chinese family with cystinuria

BACKGROUND

Cystinuria is an autosomal recessive disorder characterized by a cystine transport deficiency in the renal tubules due to mutations in two genes: SLC3A1 and SLC7A9. Cystinuria can be classified into three forms based on the genotype: type A, due to mutations in the SLC3A1 gene; type B, due to mutations in the SLC7A9 gene; and type AB, due to mutations in both genes.

METHODS

We report a 12-year-old boy from central China with cystine stones. He was from a non-consanguineous family that had no known history of genetic disease. A physical examination showed normal development and neurological behaviors. Whole-exome and Sanger sequencing were used to identify and verify the suspected pathogenic variants.

RESULTS

The compound heterozygous variants c.898_905del (p.Arg301AlafsTer6) is located in exon5 and c.1898_1899insAT (p.Asp634LeufsTer46) is located in exon10 of SLC3A1 (NM_000341.4) were deemed responsible for type A cystinuria family. The variant c.898_905del was reported in a Japanese patient in 2000, and the variant c.1898_1899insAT is novel.

CONCLUSION

A novel pathogenic heterozygous variant pair of the SLC3A1 gene was identified in a Chinese boy with type A cystinuria, enriching the mutational spectrum of the SLC3A1 gene. We attempted to find a pattern for the association between the genotype of SLC3A1 variants and the manifestations of cystinuria in patients with different onset ages. Our findings have important implications for genetic counseling and the early clinical diagnosis of cystinuria.

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

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

Pediatric urolithiasis: what can pediatricians expect from radiologists?

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

Hydration and Nephrolithiasis in Pediatric Populations: Specificities and Current Recommendations

Renal lithiasis is less frequent in children than in adults; in pediatrics, lithiasis may be caused by genetic abnormalities, infections, and complex uropathies, but the association of urological and metabolic abnormalities is not uncommon. The aim of this study is to provide a synthesis of nephrolithiasis in children and to emphasize the role of hydration in its treatment. As an etiology is reported in 50% of cases, with a genetic origin in 10 to 20%, it is proposed to systematically perform a complete metabolic assessment after the first stone in a child. Recent data in the field reported increased incidence of pediatric urolithiasis notably for calcium oxalate stones. These changes in the epidemiology of stone components may be attributable to metabolic and environmental factors, where hydration seems to play a crucial role. In case of pediatric urolithiasis, whatever its cause, it is of utmost importance to increase water intake around 2 to 3 L/m² per day on average. The objective is to obtain a urine density less than 1010 on a dipstick or below 300 mOsm/L, especially with the first morning urine. Some genetic diseases may even require a more active 24 h over-hydration, e.g., primary hyperoxaluria and cystinuria; in such cases naso-gastric tubes or G-tubes may be proposed. Tap water is adapted for children with urolithiasis, with limited ecological impact and low economical cost. For children with low calcium intake, the use of calcium-rich mineral waters may be discussed in some peculiar cases, even in case of urolithiasis. In contrast, sugar-sweetened beverages are not recommended. In conclusion, even if parents and patients sometimes have the feeling that physicians do not propose "fancy" therapeutic drugs, hydration and nutrition remain cornerstones of the management of pediatric urolithiasis.

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.

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.

Comparison of infants and children with urolithiasis: a large case series

We evaluated the demographic features, etiologic risk factors, treatment strategies, and outcome of the infants and children with urolithiasis (UL). A retrospective multicenter study was conducted including 23 Pediatric Nephrology centers in Turkey. The medical records of 2513 children with UL were reviewed. One thousand, three hundred and four boys and 1209 girls (1.1:1) were reported. The mean age at diagnosis was 39.5 ± 35 months (0.4-231 months), and 1262 patients (50.2%) were in the first year of life (infants). Most of the cases with infantile UL were diagnosed incidentally. Microlithiasis (< 3 mm) was found in 794 patients (31.6%), and 64.5% of the patients with microlithiasis were infants. Stones were located in the pelvis-calyces in 63.2% (n: 1530) of the cases. The most common stone type was calcium oxalate (64.6%). Hypocitraturia was the most common metabolic risk factor (MRF) in children older than 12 months, but in infancy, hypercalciuria was more common. Fifty-five percent of the patients had received at least one medical treatment, mostly potassium citrate. At the end of a year's follow-up, most of the patients with microlithiasis (85%) showed spontaneous remission. The rate of spontaneous stone resolution in infants was higher than in children. Spontaneous remission rate was higher in cases with MRF ( - ) stones than in MRF ( +) stones. However, remission rate with medical treatment was higher in cases with MRF ( +) stones. This study represents the results of a large series of infants and children with UL and showed that there are several differences such as underlying metabolic and anatomic abnormalities, clinical course, and stone remission rates between infants and children with urinary stone disease.

Kidney disease profile and encountered problems during follow-up in Syrian refugee children: a multicenter retrospective study

BACKGROUND

Children are one of the most vulnerable groups in conflict zones, especially those with chronic diseases. This study aimed to investigate kidney disease profiles and problems during follow-up in a population of Syrian refugee children residing in Turkey.

METHODS

Syrian refugee children aged between 0 and 18 years were included in the study. Demographic data, diagnosis, particular interventions due to nephrological problems, and problems encountered during follow-up were obtained from all participating pediatric nephrology centers.

RESULTS

Data from 633 children from 22 pediatric nephrology centers were included. Mean age of the children was 94.8 ± 61.7 months and 375 were male (59%). 57.7% had parental consanguinity and 23.3% had a close relative(s) with kidney disease. The most common kidney diseases were congenital anomalies of the kidney and urinary tract (CAKUT) (31.0%), glomerular disease (19.9%), chronic kidney disease (CKD) (14.8%), and urolithiasis (10.7%). Frequent reasons for CAKUT were nonobstructive hydronephrosis (23.0%), vesico-ureteral reflux (18.4%), and neurogenic bladder (15.8%). The most common etiology of glomerular diseases was nephrotic syndrome (69%). Ninety-four children had CKD, and 58 children were on chronic dialysis. Six children had kidney transplantation. Surgical intervention was performed on 111 patients. The language barrier, lack of medical records, and frequent disruptions in periodic follow-ups were the main problems noted.

CONCLUSIONS

CAKUT, glomerular disease, and CKD were highly prevalent in Syrian refugee children. Knowing the frequency of chronic diseases and the problems encountered in refugees would facilitate better treatment options and preventive measures.

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

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

How important urolithiasis is under 2 years of age?

Urolithiasis (UL) is a common health problem in the world and the observed incidence of this disease is increasing in the infantile period. The study included cases of UL diagnosed before the age of two who had a comprehensive analysis for possible etiologic variables and were followed for a minimum of 6 months. Of the 60 patients included in the study, 37 were male, and the male/female ratio was 1.6. The average age at diagnosis is 8.5 ± 4.5 months. Of the cases diagnosed 41 (68.3%) were before than 1 year of age. The average time for follow-up is 28.9 ± 22.6 months. There was a family history of stone disease in 41 (68.3%) cases. Twenty-four (40%) patients were treated for dehydration at least once before stone disease was identified. The number of patients presenting with symptoms is 43 (71.7%). Restlessness was noted as the main symptom. In 17 (28.3%) patients, stone disease was found incidentally. Metabolic causes (n: 19, 31.6%) were determined to be the most common underlying cause, followed by UTI-related causes (n: 12, 20%). During the follow-up, 57 (64%) of the stones spontaneously disappeared. The size of 16 (18%) stones reduced, while the size of eleven remained same (13%). Following their absence, nine (15%) of the stones reappeared. The essential strategy is to identify high-risk groups, to closely monitor them, and to take preventative interventions against modifiable conditions such as dehydration if possible.

Cost Effectiveness and Impact in Quality of Care of a Pediatric Multidisciplinary Stone Clinic

Supplemental Digital Content is available in the text.

Herein, we assess the cost-effectiveness of a multidisciplinary clinic for children with urinary stones. The clinic’s primary goals were to decrease unnecessary visits, imaging, and costs while optimizing the quality of care.

The feasibility of one-day length of hospital stay after pediatric percutaneous nephrolithotomy

PURPOSE

To evaluate the safety of one-day length of hospital stay (LOS) after pediatric percutaneous nephrolithotomy (PNL), and to study the predictors of LOS.

METHODS

A retrospective study included pediatric patients who PNL for renal calculi more than 1 cm between January 2016 and October 2019. PNL was performed in prone position. The nephrostomy tubes and ureteric catheters were removed on the second day and patients were discharged if there was no perforation or significant residual stones. The stone free rate, LOS and the surgical complications were reported. Bivariate and multivariate analysis were used to predict the LOS.

RESULTS

220 patients were identified. The median age (range) was eight (Range: 3-17) years. Stone free rate was achieved in 200 patients (91%) of patients, while residual fragments were detected in 20 patients (9%). Complications, they were reported in 50 (22.7%) patients. 184 (83.6%) of patients stayed at the hospital for only 1 day, while 36 (16. 4%) stayed more than 1 day. Of 36 patients who stayed more than one-day, 34 had complications (p value <0.001).On multivariate analysis, surgical complications was found to be the only predictor of longer LOS (p value <0.001).

CONCLUSION

Early nephrostomy tube removal and 1-day length of hospital stay could be a safe option after pediatric PNL. Surgical complications is a statistically significant predictor of longer LOS.

Comparison of Renal Stones and Nephrocalcinosis in Children: Findings From Two Tertiary Centers in Saudi Arabia

Background: Renal stones (nephrolithiasis and urolithiasis) and nephrocalcinosis are uncommon in children; however, their incidences in pediatric populations have been increasing. Patients and Methods: This multicenter retrospective study compared the clinical presentation, etiology, and outcomes of childhood nephrolithiasis or urolithiasis with those of nephrocalcinosis. Results: The study included 144 children: 93 with renal stones and 51 with nephrocalcinosis. The mean age at presentation was 72 months and 54 months for children with renal stones and nephrocalcinosis, respectively. A history of consanguinity was found in 65% and 76% of the cases of renal stones and nephrocalcinosis, respectively. Congenital anomalies of the kidneys and urinary tract (CAKUT) were present in 28 and 9.8% of the patients with renal stones and nephrocalcinosis, respectively. The most common symptoms of renal stones were flank pain (29%), hematuria (15%), and dysuria (11%). Urinary tract infection was the primary presentation in the nephrocalcinosis group (18%), followed by failure to thrive (16%), polyuria (12%), and dehydration (12%). The majority of renal stone cases were caused by metabolic disorders, including hyperoxaluria (18%), cystinuria (18%), hypercalciuria (12%), and hyperuricosuria (2%). In contrast, the most common underlying disorders in cases of nephrocalcinosis were familial hypomagnesemia, hypercalciuria, nephrocalcinosis (35%), distal renal tubular acidosis (23%), and Bartter syndrome (6%). Clinical outcomes were significantly better in children with nephrolithiasis/urolithiasis than in those with nephrocalcinosis, who showed radiological evidence of worsening/persistent calcinosis and progressed more frequently to chronic kidney disease (stage II-IV) and end-stage kidney disease. Conclusion: The average age at presentation for children with renal stones was greater than that for those presenting with nephrocalcinosis. More than 25% of the children with renal stones were found to have CAKUT. Nephrocalcinosis was associated with worse clinical outcomes related to kidney function and disease resolution than nephrolithiasis.

Characteristics of infant urolithiasis: A single center experience in western Turkey

INTRODUCTION

Urolithiasis (UL) in infancy has different incidence, etiology, presentation and course compared to UL in childhood and in adults. We evaluated the clinical, radiological, metabolic factors and course of infant UL in western Turkey.

METHODS

Medical records of the infants between 1 and 12 months of age with a diagnosis of UL were reviewed retrospectively for gender, gestational age, age at diagnosis, presenting symptoms, past medical history, parental consanguinity, family history of UL, urinary tract abnormalities, urinary tract infections, localization-size-number of stones, course of stones, treatment modality of UL (medical vs surgical) and follow up duration. Patients were grouped as those who did not require surgical intervention (Group 1) and those who underwent any kind of stone surgery (Group 2). Both groups were compared for the study parameters.

RESULTS

There were 80 infants (48 males) with a mean age of 6.0 ± 2.9 months at diagnosis. Mean follow-up duration was 29.7 ± 23.1 months. Two thirds of the patients presented with symptoms/signs not directly related to urinary system. Predisposing factors included metabolic abnormalities in 24 (30%) patients and urinary tract malformations in 9 (11%) patients. Group 1 (n = 58) and Group 2 (n = 22) were not different with respect to the study parameters except for the larger stone size and higher rate of hyperuricosuria in Group 2. Stone size of 4.5 mm has a 72.7% sensitivity and 74.1% specificity for predicting surgical intervention. Infants treated medically and those followed by hydration only did not differ for regression rate of stones and for requirement for surgical intervention. However, metabolic abnormalities were significantly higher in medically treated infants.

CONCLUSION

Every infant with urolithiasis should be evaluated for risk factors. Modification of such predisposing factors when possible may mitigate the notably high recurrence rate of UL in children. Increased awareness of infant UL may allow for earlier detection, improved evaluation and follow up, and may thereby decrease the morbidity of the disease.

The interest of oral calcium loads test in the diagnosis and management of pediatric nephrolithiasis with hypercalciuria: Experience from a tertiary pediatric centre

INTRODUCTION

The use of calcium load has been forgotten in pediatrics until recently whereas it is of utmost importance to have a practical approach to guide management of hypercalciuric nephrolithiasis.

OBJECTIVE

The purpose of this study was to evaluate the practical interest of oral calcium loads to improve the overall management of nephrolithiasis in children.

METHODS

We retrospectively studied all pediatric patients having undergone an oral calcium load in our pediatric nephrology unit between September 2015 and April 2017.

RESULTS

A total of 16 patients were included, at a median age of 12.0 (5.5-17.5) years. The indications of oral calcium load were: presence of an active urolithiasis without any obvious explanation after ruling out the "classical" biological abnormalities, or presence of hypercalciuria with stones composed of weddellite or carbapatite crystals. Among the 16 patients, 6 (38%) patients displayed absorptive hypercalciuria, 2 (12%) renal leak, 3 (19%) "unclassified" inadapted PTH, and 5 (31%) a normal calcium load test. The result of oral calcium load modified the clinical management in 14 (88%) patients, mainly based on the type of hypercalciuria. It allowed us to individualize nutritional advice: in patients with absorptive hypercalciuria, we proposed calcium intake within the lower normal range for age with dairy products not enriched with vitamin D, with the advice to avoid salt and calcium loads during evenings. Conversely, in patients with resorptive hypercalciuria, we proposed normal calcium intake for age. Showing the results of the calcium load is meaningful to patients and parents, and can be considered as an "educational" tool.

DISCUSSION

To the best of our knowledge, this study is the first to evaluate the interest of calcium load in children with nephrolithiasis in an era of routine PTH and 1-25-D assessment. Here, we demonstrate the feasibility and safety of oral calcium load in children, its interest to understand the underlying mechanisms of hypercalciuria, and its major interest as an "educational tool" for patients to explain them the underlying mechanisms and thus guide the therapeutic management using an individualized dietary approach. This study did not include many patients, but to the best of our knowledge, this is the first study evaluating and validating the feasibility of a safe and non-expensive diagnosis tool in pediatric hypercalciuria.

CONCLUSION

Oral calcium load is helpful to guide therapeutic adaptation in pediatrics using an individualized dietary approach.

The Possible Beneficial Effect of Breastfeeding on the Clinical Course of Urolithiasis Detected During Infancy

Aim: To evaluate the possible effect of breastfeeding duration on the clinical course and treatment of stones detected during infancy. Materials and Methods: Forty-eight infants with renal stones diagnosed between 0 and 23 months were included in this retrospective cohort study. The children were called for regular follow-up visits for the evaluation of physical examination findings, renal size and parenchymal thickness measured by ultrasonography, localization, size and number of stones, spot urine analysis data, metabolic evaluation findings, and duration of breastfeeding and formula use. The relationship between the disease course (progression or stability) and the duration of breastfeeding were assessed from different aspects by considering the original characteristics of the stones at the time of first diagnosis. Results: The mean follow-up period was 46.21 ± 23.22 months, and the most important metabolic risk factor was hypercalciuria with a rate of 29.2%. The mean duration of breast milk intake was longer in children with no disease progression and in those with a reduced size and/or number of stones. The children receiving only breast milk for the first 6 months of life required treatment less and had less growth retardation. Conclusions: Our findings suggest that breastfeeding has critical effects on infantile urolithiasis. Breastfeeding should be encouraged in children with stones particularly detected during infancy. Further studies with a larger case series are needed to reveal the positive effects of breast milk on the clinical course of urolithiasis in children.

Risk factors for development of urinary tract infection in children with nephrolithiasis

AIM

Nephrolithiasis is one of the causes of urinary tract infection (UTI). In this study, we investigated risk factors for UTI in children with nephrolithiasis.

METHODS

The data from the patients with nephrolithiasis were evaluated in this retrospective follow-up study. Patients with a history of UTI before admission and congenital anomaly of kidney or urinary tract were excluded. The patients were divided into two groups: patients with UTI (recurrent UTI and single UTI) and patients without UTI.

RESULTS

A total of 599 patients were included in this study. UTI occurred in 181 (30.2%) patients. There was a positive association between the size of stone and UTI (odds ratio (OR): 1.355, P = 0.007). Receiver operating characteristic curve analysis showed that the cut-off value of the size of stone for UTI was 5.3 mm, with a sensitivity of 74.9% and a specificity of 66.1% (area under the curve: 0.572 ± 0.028, P = 0.013). The presence of a metabolic risk factor and age at diagnosis under 2 years were significantly associated with both UTI and recurrence of UTI (OR: 2.272, P = 0.021, OR: 1.809, P = 0.028, respectively, for metabolic risk factor; OR: 1.212, P = 0.041, OR: 1.122, P = 0.046, respectively, for age at diagnosis under 2 years). Hypercalciuria was significantly associated with the recurrence of UTI (OR: 1.854, P = 0.017).

CONCLUSIONS

The age at diagnosis, the presence of a metabolic risk factor and size of stone are significant risk factors for UTI in children with nephrolithiasis. The patients with idiopathic hypercalciuria, metabolic risk factor and age at diagnosis under 2 years have increased risk of recurrence of UTI.

Multidimensional Analysis of Urinary Stone Diseases in Pediatric Patients

Objectives:

Urinary tract stones are less common in children than in adults. Determining the etiology is the most important step to achieve successful treatment and prevent future recurrence. The aim of this study was to investigate the clinical characteristics and possible risk factors for urinary stone disease in pediatric patients.

Methods:

The data of 126 patients with urinary stone disease who were treated in a pediatric nephrology clinic between 2000 and 2014 were analyzed retrospectively. A total 126 patients were enrolled in the study: 70 (55%) male and 56 (45%) female patients were included. The complaints, age of diagnosis, family histories, and stone location were examined. Direct urine microscopic examination, complete urinalysis, and urine culture were performed for all of the patients. Calcium, uric acid, oxalate, citrate, magnesium, and cystine levels were measured in urine collected in a 24-hour period. Serum electrolyte, blood urea nitrogen, creatinine, calcium, phosphorus, uric acid, and albumin levels were measured. Urinary ultrasound was performed. Stone analysis was conducted using the X-ray diffraction method. The mean age of the patients was 55 months (range: 1-162 months) at presentation.

Results:

In all, 34% of the patients had a family history of urinary stone disease. The rate of previous urinary tract infection was 26%. It was determined that 34% of the patients had been taking vitamin D and 5% had been taking a high dose. Metabolic risk factors determined were: hypercalciuria in 41%, hypocitraturia in 30%, hyperoxaluria in 14%, hyperuricosuria in 10%, and cystinuria in 5%. Among the group, 81% of the patients had kidney stones, 6.5% had ureter stones, and 2.5% had bladder stones. Furthermore, it was determined that 45% of the stones were composed of calcium oxalate, 35% had calcium phosphate stones, 14.2% had uric acid stones, and 13.3% had cystine stones. In 52% of the cases, extracorporeal shock wave lithotripsy was performed, and 71% underwent surgical treatment.

Conclusion:

Metabolic evaluation and stone analysis should be performed to prevent future recurrences in children with urinary stone disease and lifelong follow-up should be emphasized.

ACR Appropriateness Criteria® Hematuria-Child

Hematuria is the presence of red blood cells in the urine, either visible to the eye (macroscopic hematuria) or as viewed under the microscope (microscopic hematuria). The clinical evaluation of children and adolescents with any form of hematuria begins with a meticulous history and thorough evaluation of the urine. The need for imaging evaluation depends on the clinical scenario in which hematuria presents, including the suspected etiology. Ultrasound and CT are the most common imaging methods used to assess hematuria in children, although other imaging modalities may be appropriate in certain instances. This review focuses on the following clinical variations of childhood hematuria: isolated hematuria (nonpainful, nontraumatic, and microscopic versus macroscopic), painful hematuria (ie, suspected nephrolithiasis or urolithiasis), and renal trauma with hematuria (microscopic versus macroscopic). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Efficacy and Reliability of Retrograde Intrarenal Surgery in Treatment of Pediatric Kidney Stones

Introduction 

Surgical treatment of pediatric kidney stones has dramatically changed in recent years due to the miniaturization of surgical instruments and the availability of intracorporeal lithotriptors. Retrograde intrarenal surgery (RIRS) technique is now considered an effective and minimally invasive procedure in renal stones. However, in the pediatric age group, the number of studies on this subject is very limited. The aim of this study was to evaluate the efficacy and safety of the RIRS in the treatment of kidney stones in children.

Material and methods 

The data of 25 pediatric stone patients who underwent RIRS with the diagnosis of kidney stones were analyzed retrospectively. Demographic characteristics, operative data, and success rates of the patients were recorded.

Results 

Fourteen (56%) of the cases were male and 11 (46%) were female. The mean age was 10.43 ± 4.26 (3-15) in boys and 10.18 ± 4.92 (4-16) in girls. Eleven stones (46%) were in the left kidney and 14 (56%) in the right kidney. The mean stone size was 10.08 ± 4.33 mm (4-23). Stone localizations were renal pelvis in 15 (60%) cases, upper calyx in four (16%) cases, middle calyx in five (20%) cases, and lower calyx in one (4%) case. The mean operation time was 41.20 ± 6.96 minutes (30-60), the mean duration of scope was 17.40 ± 3.85 seconds (10-30), and the mean hospital stay was 2.32 ± 0.63 days (2-4). Three patients (12%) had undergone percutaneous nephrolithotomy (PCNL), and two (8%) patients underwent shockwave lithotripsy (ESWL) before this surgery. In six (24%) patients, a double J (DJ) catheter was inserted due to stenosis at the lower end of the ureter. Body mass index (BMI) of these patients was below 18. An access sheath was implanted in six (24%) patients in the second operation. In 18 cases, the first operation was performed with a direct flexible renoscope. In all cases, a postoperative DJ catheter was inserted. Postoperative fever was observed in one (4%) patient, and ureteric steinstrasse was observed in one (4%) patient. The stone-free rate was achieved as 17% (68%) after the first operation and 100% after the second RIRS session.

Conclusion 

RIRS appears to be an effective and reliable method in the pediatric age group. However, there is a need for multicentre studies involving more cases.

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.

Treatment of upper urinary tract stones with flexible ureteroscopy in children

INTRODUCTION

This single-centre, retrospective study aimed to assess the efficacy and safety of flexible ureteroscopy (FURS) combined with holmium laser lithotripsy in treating children with upper urinary tract stones.

METHODS

From June 2014 to October 2015, a total of 100 children (74 boys and 26 girls) with upper urinary tract stones were treated using FURS. A 4.7 Fr double-J stent was placed two weeks before operation. Patients were considered stone-free when the absence of residual fragments was observed on imaging studies. The preoperative, operative, and postoperative data of the patients were retrospectively analyzed.

RESULTS

A total of 100 pediatric patients with a mean age of 3.51±1.82 years underwent 131 FURS and holmium laser lithotripsy. Mean stone diameter was 1.49±0.92 cm. Average operation time was 30.8 minutes (range 15-60). The laser power was controlled between 18 and 32 W, and the energy maintained between 0.6 and 0.8 J at any time; laser frequency was controlled between 30 and 40 Hz. Complications were observed in 69 (69.0 %) patients and classified according to the Clavien system. Postoperative hematuria (Clavien I) occurred in 64 (64.0 %) patients. Postoperative urinary tract infection with fever (Clavien II) was observed in 8/113 (7.1%) patients. No ureteral perforation and mucosa avulsion occurred. The overall stone-free rate of single operation was 89/100 (89%). Stone diameter and staghorn calculi were significantly associated with stone-free rate.

CONCLUSIONS

FURS and holmium laser lithotripsy is effective and safe in treating children with upper urinary tract stones.

Factors Affecting the Success Rate of Percutaneous Nephrolithotomy in Paediatric Patients

In this study, we aimed to determine factors affecting the success rate of percutaneous nephrolithotomy (PNL) in children. The series consisted of 41 consecutive children operated on by the same surgical team for renal calculi with PNL between June 2002 and May 2015 in our institution. A single calyx or pelvic stone was described as simple, while calculi located in more than one location (calyx and pelvis or more than one calices) or staghorn stones were described as complex. The procedure was deemed successful if the patient was completely stone-free (SF) or had residual fragments <4 mm. Thirty-four patients were found to be SF or had residual fragments <4 mm on the postoperative first day, thus the success rate was 82.9%. In complex stones, the success rate was significantly lower (45.5%) than simple stones (96.7%) (p < 0.001). The grade of hydronephrosis (Grade 0–1 vs. Grade 2–3) also had a negative impact on the success, with rates of 92.6% vs. 64.3%, respectively (p = 0.022). Previous urological procedure history on the same side yielded a success rate of 58.3%, whereas the success rate in the primary patients was 93.1% (p < 0.001). The localization of the stone (complex vs. simple), degree of hydronephrosis, and history of previous urological procedures were found to be the factors that affected the success of the paediatric PNL.

Pediatric hospitalizations for upper urinary tract calculi: Epidemiological and treatment trends in the United States, 2001-2014

INTRODUCTION

The incidence of urolithiasis in the pediatric population in the United States has steadily been increasing over the past few decades. Few studies to date have examined trends in the hospitalization and inpatient surgical treatment of urolithiasis in the pediatric population using nationally representative data.

OBJECTIVE

The aim was to evaluate nationwide trends in the rates of pediatric hospitalization and inpatient surgical activity for upper urinary tract calculi (UUTC) in the United States from 2001 to 2014.

PATIENTS AND METHODS

The National Inpatient Sample (NIS) databases for 2001-2014 were queried. Hospitalizations for patients younger than age 18 (excluding newborns), with principal discharge diagnoses of kidney or ureteral calculi were selected. Surgical procedures during hospitalization were identified. Hospitalization and surgical activity data were analyzed using trends tests, chi-square statistics, and multivariable logistic regression as appropriate.

RESULTS

Of an estimated 30.2 million pediatric hospitalizations during the study period, 44,369 overall (147 per 100,000) were for UUTC. The total number and proportion of UUTC hospitalizations per 100,000 all-cause admissions significantly decreased between 2001 and 2014 (p < 0.0001) (figure). Surgical intervention was undertaken in 19,946 (45%) of UUTC hospitalizations, with significantly increasing frequency over the study interval (p < 0.0001). Urinary tract drainage was the most frequently performed surgical intervention. On multivariable analysis, significant predictors of a higher likelihood of undergoing inpatient surgical intervention during hospitalization for UUTC included older age, female gender, deficiency anemias, hypertension, neurologic disorders, paralysis, and hospitalization after 2001.

DISCUSSION

The declining trend in hospitalization for UUTC likely reflects a shift toward outpatient care for routine cases, reserving hospitalization for sicker patients or those with complications of urolithiasis. Similar to previous studies, we also observed that girls were significantly more likely than boys to be hospitalized for stone disease, and that majority of the stone activity in the pediatric population was in children aged 15-17 years. We also observed a sharp increase in the proportion of hospitalized patients who underwent surgical intervention between 2001 and 2014, but the primary driver of this trend remains uncertain.

CONCLUSION

Pediatric hospitalizations for UUTC in US children significantly decreased between 2001 and 2014, while of those hospitalized the proportion who underwent stone-related surgical intervention significantly increased over the same period. A shift towards outpatient care, reserving hospitalization and inpatient surgical care for sicker patients, those with urolithiasis-related complications, or those who fail conservative management, is a possible explanation for these observed trends.

Metabolic evaluation of children with urolithiasis

Aim:

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

Materials and Methods:

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

Results:

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

Conclusion:

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

Composition of urinary calculi in infants: a report from an endemic country

Pediatric urolithiasis remains endemic in low-resource countries where infants constitute 17-40% of all children with urolithiasis. This study reports socio-economic factors, medical history and chemical composition of urinary stones in 976 infants of up to 2 years of age. Between 1992 and 2016, 976 infants presented to our institute with 1038 stones. Chemical composition of stones was analyzed by Fourier transformation infrared spectroscopy (FTIR). The mean age of infants was 19.5 ± 5.74 months with a M:F ratio of 5.5:1. Half (50%) of the infants were rural dwellers, 90% belonged to low socio-economic class and 70% were malnourished. A history of chronic diarrhoea was reported in 13% and urinary tract infections in 5%. The anatomic location was bladder in 487 (46.9%), kidney in 246 (23.6%), ureter in 142 (13.6%), urethra in 2 (0.2%) and 161 (15.5%) were passed spontaneously. Overall frequency of compounds in stones showed ammonium acid urate (AAU) in 772 (74.37%), calcium oxalate (CaOx) in 410 (39.5%). Uric acid (UA) in 119 (11.46%), calcium phosphate apatite (CaP) in 96 (9.25%), magnesium ammonium phosphate (Struvite) in 45 (4.34%), cystine in 12 (1.16%) and xanthine in 40 (3.85%). Frequency of compounds was similar in genders. Infants of age 0-6 months had higher frequency of UA (28%), CaOx (50%) and low AAU (61%) as compared to 11, 39 and 75%, respectively, in 7-24 months (p < 0.049) (p < 0.002) (p < 0.001). Nucleus of stones showed pure AAU in 63 and 43% on the surface due to addition of CaOx, struvite and CaP. Our study has shown that AAU is a major component of stones in infants where the main risk factors are poverty, malnutrition, diarrheal diseases and dehydration.

Etiologic risk factors and vitamin D receptor gene polymorphisms in under one-year-old infants with urolithiasis

The incidence of urinary tract stones in infancy has been increasing in Turkey. Risk factors and vitamin D receptor (VDR) gene polymorphisms were investigated in infants aged < 1 year who had stones. Forty infants with urinary tract stones and 80 infants without stones, aged < 1 year were enrolled in this study. Detailed surveys were taken of all infants, metabolic parameters and ApaI and FokI VDR gene polymorphisms were investigated. Infants with stones tended to be more commonly fed formula and multivitamins (vitamins A, C, D) (p < 0.05). Positive family history came into prominence in the stony group (p < 0.05). There were no significant differences in ApaI and FokI VDR gene polymorphisms between the groups with stones and the control groups. However, CA genotype of ApaI polymorphism was associated with family history and C allele of ApaI was related with family history and hypercalciuria (p < 0.05). Hypercalciuria emerged as an underlying metabolic abnormality in the etiology of stones, and was observed at a rate of 38%. Infants who are given formula and multivitamins for vitamin D supplementation are at increased risk for the formation of urinary tract stones. VDR gene polymorphisms cause the formation of urinary tract stones and affect calcium (Ca) metabolism.

E-cadherin gene polymorphisms and susceptibility to urolithiasis in Iraqi children

AIM

This case/control study aimed to assess the impact of two single nucleotide polymorphisms (SNPs) in the promoter region of CDH1 gene (-160C>A and -347G>GA) on urinary stone formation in a sample of Iraqi children.

METHODS

Forty-seven children with urolithiasis and 50 age- and gender-matched healthy controls were included in the study. DNA was isolated from peripheral blood and direct sequencing was used for genotyping.

RESULTS

The homozygous genotype of the SNP CHD1 -160C>A was more frequent in control than cases (18% vs. 6.38%) with significant difference (OR = 0.229, 95%CI = 0.056-0.943, P = 0.041). Furthermore, cases showed significantly less frequency of the mutant allele (allele A) of this SNP (OR = 0.403, 95%C = 0.210-0.776, P = 0.007).

CONCLUSION

These results strongly indicate a protective role of allele A of the SNP CHD1 -160C>A against urinary calculi formation in children.

Endemic bladder calculi in children

Urinary calculi are being recognized more frequently in children and the urinary bladder is the most common site for stone formation in the lower urinary tract. Bladder calculi are grouped into three basic categories: primary idiopathic/endemic, secondary, and migrant. The incidence of vesical calculi has declined significantly in the last 70 years in developed nations owing to improvements in nutrition and socioeconomic conditions, but it is still high in developing nations. Primary idiopathic/endemic bladder calculi typically occur in children, in the absence of urinary tract infection (UTI), urinary stasis, or foreign body, and diet lacking in animal proteins is the major contributor factor. Comprehensive preventive and treatment strategies are critical for improving the quality of life of diseased children, in addition to helping to eradicate, or at least decrease, the incidence of endemic bladder calculi in developing nations.

Urinary biomarkers in the early detection and follow-up of tubular injury in childhood urolithiasis

BACKGROUND

To investigate relationships among urinary biomarkers [kidney injury molecule-1 (KIM-1), N-acetyl-β-glucosaminidase (NAG)], neutrophil gelatinase-associated lipocalin (NGAL) levels and renal tubular injury in childhood urolithiasis.

METHODS

Seventy children [36 girls, mean age: 7.3 ± 5.0 years (0.5-18.2)] with urolithiasis/microlithiasis and 42 controls [18 girls, mean age: 8.5 ± 3.8 years (0.9-16.2)] were included in this multicenter, controlled, prospective cohort study. Patients were evaluated three times in 6-month intervals (0, 6 and 12th months). Anthropometric data, urinary symptoms, family history and diagnostic studies were recorded. Urine samples were analyzed for metabolic risk factors (urinary calcium, uric acid, oxalate, citrate, cystine, magnesium, and creatinine excretion), and the urinary KIM-1, NAG, and NGAL levels were measured.

RESULTS

Stones were mostly located in the upper urinary system (82.9%), and six patients (8.6%) had hydronephrosis. Thirty patients (42.9%) had several metabolic risk factors, and the most common metabolic risk factor was hypocitraturia (22.9%). Urinary KIM-1/Cr, NAG/Cr and NGAL/Cr ratios were not significantly different between patients and controls. Furthermore, no significant changes in their excretion were shown during follow-up. Notably, the urinary KIM-1/Cr, NAG/Cr, and NGAL/Cr levels were significantly higher in children under 2 years of age (p = 0.011, p = 0.006, and 0.015, respectively). NAG/Cr and NGAL/Cr ratios were significantly increased in patients with hydronephrosis (n = 6, p = 0.031 and 0.023, respectively).

CONCLUSIONS

The results of this study suggest that none of the aforementioned urinary biomarkers (KIM-1, NAG and NGAL levels) may be useful for the early detection and/or follow-up of renal tubular injury and/or dysfunction in childhood urolithiasis.

What do we know about pediatric renal microlithiasis?

Renal or calyceal microlithiasis is a common disorder with increasing prevalence especially in infants and younger children. The main presenting symptoms and the underlying metabolic abnormalities of renal microlithiasis are similar to renal stone. Although renal microlithiasis is considered as a main problem of the health system with diverse etiologies, our information about its natural course is very limited. Hence, further investigations to make an appropriate clinical approach to this entity is mandatory. Also, general practitioners, pediatricians, nephrologists and urologists have to be well educated regarding renal microlithiasis for early diagnosis, appropriate evaluation and proper management of this entity. In this review study, we focused on collection of the present information about different aspects of renal microlithiasis in children.

Why we need a higher suspicion index of urolithiasis in children

BACKGROUND

Most children with symptoms of urolithiasis and urinary solute excretion abnormalities leading to stone formation have no calculi revealed by ultrasound or X-ray plain film ("occult urolithiasis"). This covers a large group of children presenting with common symptoms such as abdominal pain, hematuria, and dysuria, often faced by general practitioners and pediatricians. However, half or more of children with urolithiasis could present with abdominal/flank pain without specific urinary symptoms.

STUDY DESIGN

We review the current evidence about prevalence, clinical presentation, and radiological detection of overt and "occult" urolithiasis in children, aiming to give readers the instruments to suspect and diagnose urolithiasis while avoiding cost-ineffective and undue diagnostic procedures.

CONCLUSIONS

It is important to investigate for urolithiasis first by ultrasound and, in specific cases, by urinary metabolic and different imaging studies in the following groups: 1) in children with non-glomerular hematuria or/and dysuria not presenting inflammation of external genitalia; 2) in children with acute/sub-acute or infrequent recurrent abdominal pain and family history of urolithiasis in first or second degree relatives or being at higher risk of developing stones although hematuria and dysuria are lacking; 3) in children under 8 years old, even though pain is central or diffuse to the whole abdomen; and 4) in children presenting risk factors or conditions predisposing to urolithiasis. Finally, it seems reasonable to repeat ultrasound 1-2 years later also in children with "occult" urolithiasis and high risk of developing stones to detect any (re-)appearance of calculi.

Metabolic risk factors in pediatric stone formers: a report from an emerging economy

The goal of this study was to investigate metabolic risk factors in pediatric stone formers in an emerging economy. A prospective, data collection enrolled 250 children age <1-15 years at our center. Risk factors were evaluated by gender and in age groups <1-5, 6-10 and 11-15 years. Patients were evaluated for demographics, blood and 24 h urine for calcium, magnesium, phosphate, uric acid, electrolytes and additional protein, citrate, ammonia and oxalate in urine. All reported values were two sided and statistical significance was considered at p value ≤0.05. The mean age at diagnosis was 7.50 ± 3.56 years with a male to female ratio of 1.84:1. A family history of urolithiasis was found in 41 (16.4 %), urinary tract infection in 18 (7 %) and chronic diarrhea in 75 (30 %). Hypercalcemia was seen in 37 (14.8 %), hyperuricemia in 23 (9.2 %) and hyperphosphatemia in 6 (2.4 %). Urinary metabolic abnormalities were identified in 248 (98 %) of the cases. Hypocitraturia was found in 207 (82.8 %), hyperoxaluria in 62 (26.4 %), hyperuricosuria in 82 (32.8 %), hypercalciuria in 51 (20.4 %), hyperphosphaturia in 46 (18.4 %), hyperammonuria in 10 (4 %), hypocalciuria in 82 (32.8 %), and hypovolemia in 73 (29.2 %). Risk factors were similar between genders except higher rates of hyponatriuria, hypophosphaturia, and hypocalciuria in females. Hyperuricosuria, hyponatriuria, and hypovolemia were highest in 1-5 years (52, 49, 49 %) as compared to (18, 21, 12 %) those in 11-15 years (p < 0.001), respectively. This study shows that careful metabolic analysis can identify risk factors in 98 % of the children where appropriate metaphylaxis can be undertaken both for treatment and prevention of recurrence.

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.

Metabolic Evaluation in Paediatric Urolithiasis: A 4-Year Open Prospective Study

INTRODUCTION

Children with urolithiasis are associated with considerable morbidity and commonly associated with metabolic abnormalities. By treating these abnormalities stone formation is prevented.

OBJECTIVES

To study the metabolic risk factors of urolithiasis in children and compare them with literature.

MATERIALS AND METHODS

In open, prospective and observational study, 75 children were evaluated from August 2010 to June 2014. In all patients' dietary history, water intake and results of laboratory findings were recorded. All urine samples obtained from patients were without dietary restrictions. Reference paediatric 24 hour urinary parameter was used according to western literature.

RESULTS

We investigated 75 patients with urolithiasis. Low urine volume was found in 49 patients which is comparable with previous studies indicating simple intervention as to increase water intake. Low calcium intake was found in 44 patients suggesting that low calcium intake is associated with higher incidence of urolithiasis due to increased intestinal oxalate absorption. Hypocalcaemia was found in 32 patients and 24 hour urinary abnormality was found in only 16 patients'. Both these finding does not support previous literature. Stone analysis finding does not correlate with urinary finding.

CONCLUSIONS

Low urine volume secondary to low water intake is predominant finding. Hypocalcaemia is major metabolic abnormality in contradiction to western literature. There are no nomograms for urinary excretion of Calcium, uric acid, oxalate and citrate in Indian children. Keeping the optimum blood calcium level & increased fluid intake can prevent stone formation in children.

A Comparison between Clinical and Metabolic Features of Renal Calyceal Microlithiasis and Overt Urolithiasis in Different Pediatric Age Groups

INTRODUCTION

This study assesses the differences in the presentations, complications and metabolic abnormalities of children with renal calyceal microlithiasis (RCM) and overt urolithiasis in different pediatric ages.

MATERIALS AND METHODS

A total of 465 children with urolithiasis were investigated retrospectively. Patients were categorized based on their ages to infancy, early childhood, middle childhood and adolescence. When the hyperechogenic spots on ultrasound imaging were <3 mm, they were considered RCM, and if they were ≥3 mm, they were considered overt urolithiasis.

RESULTS

Metabolic abnormalities were detected in 71%; hyperuricosuria in infants, hyperoxaluria in younger children and hypocitraturia in older children were the most common metabolic abnormalities. Hypercalciuria was the only metabolic abnormality that was significantly associated with overt urolithiasis in all pediatric ages (OR 2.25, 95% CI 1.21-4.19). The clinical presentations were not significantly different between RCM and overt urolithiasis; however, complications such as urinary tract infection was significantly higher with overt urolithiasis in infancy (p = 0.01), early childhood (p = 0.02), middle childhood (p = 0.007) and adolescence (p = 0.01). Also, growth retardation was significantly higher with overt urolithiasis in infancy and early childhood (p = 0.02).

CONCLUSIONS

Most children with urolithiasis have underlying urinary metabolic abnormalities that differ according to the child's age. Despite these differences, hypercalciuria is significantly associated with overt urolithiasis in all pediatric ages. Clinical and laboratory features cannot differentiate RCM and overt urolithiasis; however, complications are significantly higher with overt urolithiasis.

Pediatric primary urolithiasis: Symptoms, medical management and prevention strategies

In the past few decades pediatric urolithiasis has become more frequent. The reason for this increase is not completely clear but has been attributed to changes in climate, nutritional habits and possibly other environmental factors. Although less frequent than adult stone disease, urolithiasis in the pediatric age group is also related to significant morbidity, particularly since stones tend to recur, and, thus, should not be underestimated. Most children with idiopathic stone disease have an underlying metabolic abnormality substantiating the importance of metabolic evaluation already following initial diagnosis of urolithiasis. Identification of the metabolic abnormality allows for more specific prescription of non pharmacological and pharmacological interventions aimed at preventing recurrent stone formation. A better understanding of the causes of kidney stone disease will provide better strategies for stone prevention in children.

Urinary excretion of calcium, magnesium, phosphate, citrate, oxalate, and uric acid by healthy schoolchildren using a 12-h collection protocol

BACKGROUND

Improving knowledge about normal urine composition in children is important for early prevention of lithiasis. We describe urinary excretion values of calcium (Ca), magnesium (Mg), phosphate (P), citrate (Cit), uric acid (Ur), and oxalate (Ox) in healthy children with and without a family history of lithiasis, using a 12-h urine collection protocol.

METHODS

Urine samples were obtained from 184 children (5-12 years): a spot sample collected in the afternoon, and a 12-h overnight sample. Solute/creatinine (Cr) and 12-h solute excretion was calculated.

RESULTS

Urinary excretion values of the studied solutes are presented as percentile values, separately for each type of sample. Due to age-related differences in the solute/creatinine ratios, except for Ca and Cit, results are described according to the child's age. The presence of excretion values related to an increased risk of lithiasis was more common in children with a family history.

CONCLUSIONS

We report data from urine samples collected by using a simplified collection protocol. The observed differences between children with and without a family history of lithiasis could justify that in population studies aimed at setting reference values, the former are excluded.