An update on the changing epidemiology and metabolic risk factors in pediatric kidney stone disease

Global burden of pediatric urolithiasis: A trend and health inequalities analysis from 1990 to 2021

This research seeks to evaluate the worldwide burden, health inequities, and projected trends of pediatric urolithiasis from 1990 through 2021. We calculated age-standardized incidence rates, prevalence rates, and disability-adjusted life years rates from the 2021 Global Burden of Disease database. Joinpoint regression was applied for time-trend analysis. Health disparities were measured by using Spearman correlation analysis, Relative Concentration Index, and Slope Index of Inequality. Bayesian Age-Period-Cohort models predicted future global age-standardized incidence rates trends. Global age-standardized incidence rates declined from 79 (95% confidence interval [CI], 38-132) cases per 100,000 population in 1990 to 75 (95% CI, 37-124) cases per 100,000 in 2021, although the total number of cases rose. Age-standardized incidence rates decrease sharper in high Socio-Demographic Index regions. Geographical differences reveal significant health disparities, with age-standardized disability-adjusted life years rates higher in countries with a low Socio-Demographic Index. Bayesian Age-Period-Cohort models forecast a slight rise in global age-standardized incidence rates.

CONCLUSIONS

While global age-standardized incidence rates for pediatric urolithiasis have shown a downward trend, the increasing number of cases and persistent age-standardized disability-adjusted life years rates burden in low-SDI regions underscore pressing concerns. Efforts focused on prevention, early detection, and equitable access to healthcare are critical to bridging these gaps and improving global outcomes.

WHAT IS KNOWN

• Pediatric urolithiasis imposes a significant global burden, with higher recurrence rates and long-term impacts on kidney function. • The incidence of urolithiasis in children varies greatly in different countries or regions around the world.

WHAT IS NEW

• This study provides the comprehensive analysis of global trends and health inequalities in pediatric urolithiasis from 1990 to 2021 using GBD 2021 data. • Persistent inequalities remain, with disadvantaged regions bearing heavier burdens despite global improvements.

Comprehensive analysis of pediatric urolithiasis in a tertiary care center and insights into demographics, risk factors, and management outcomes

BACKGROUND

Pediatric urolithiasis is a growing global health concern, with increasing incidence and potential risks for chronic kidney disease if untreated. Contributing factors include metabolic disorders, genetic predisposition, dietary influences, and regional variations. Despite advancements in diagnosis and treatment, management remains challenging, particularly in high-risk infants.

OBJECTIVE

This study investigates the clinical characteristics, metabolic risk factors, and treatment outcomes of pediatric urolithiasis in a tertiary care center in Türkiye. Special attention is given to infants, assessing their distinct metabolic and clinical features, treatment responses, and the effectiveness of conservative management. Additionally, factors influencing stone burden and recurrence are evaluated to support individualized, risk-based management.

METHODS

We retrospectively analyzed 308 children (0-18 years) diagnosed with urinary stones. Demographic data, clinical presentation, laboratory and imaging findings, treatment strategies, and outcomes were reviewed. Metabolic evaluations included urinary levels of citrate, oxalate, and calcium. Treatment approaches varied based on stone size, location, and symptoms, ranging from conservative management to medical therapy and surgical interventions.

RESULTS

The median age at diagnosis was 12.5 months (range: 0-214), with a high prevalence of infant-onset cases. A family history of urolithiasis was present in 59.9 %, and parental consanguinity in 31.2 %. At the first visit, hypocitraturia (46.5 %), hyperoxaluria (36 %), and hypercalciuria (11.3 %) were common. Infants had higher rates of bilateral and multiple stones, while older children had larger stones (>5 mm, p < 0.001). Among infants with bilateral, multiple stones, hypocitraturia and hyperoxaluria were detected in 68.7 % and 66.1 %, respectively at follow-up, emphasizing the need for serial metabolic assessments. Nearly 70 % of patients received medical therapy, primarily Shohl's solution, while 28.2 % were managed conservatively. Among those with stones ≤5 mm, one-third were observed without intervention, with no significant difference in stone-free rates. Surgical interventions included extracorporeal shock wave lithotripsy (21.8 %), percutaneous nephrolithotomy (8.8 %), ureterorenoscopy (12.3 %), and open surgery (2.3 %).

DISCUSSION

Comparable stone-free rates between treated and untreated small stones (≤5 mm) support the role of conservative management in selected cases without metabolic risk factors. However, the high rate of surgical interventions highlights the need for individualized treatment. Early-onset urolithiasis is frequently bilateral and multiple, reinforcing the importance of serial urine testing for accurate diagnosis.

CONCLUSION

Pediatric urolithiasis generally has a favorable prognosis with early diagnosis and tailored management. High-risk infants require proactive metabolic evaluation and long-term follow-up, as metabolic abnormalities may not be present at initial diagnosis. These findings support a risk-based, individualized approach to pediatric urolithiasis management.

Pediatric Nephrolithiasis: A Changing Landscape Through Time and Space

Pediatric nephrolithiasis is an ancient and complex disorder that has seen a significant rise in recent decades and the underlying causes contributing to stone formation in children may also be shifting. Historically, kidney stones have been linked to factors such as metabolic disorders, congenital abnormalities, and family history. However, the recent increase in incidence appears to be associated with new risk factors, including changes in lifestyle and diet, the growing prevalence of obesity, metabolic syndrome, diabetes, and even climate change. Given this evolving landscape, performing a comprehensive metabolic evaluation during the diagnostic process is essential. A complete metabolic evaluation should thus be performed during the diagnostic assessment to identify any modifiable risk factors predisposing to stone recurrence and reduce the need for surgical management, extrarenal comorbidity, and the increased burden of care.

Cornelia de Lange Syndrome Accompanied by Cholelithiasis and Nephrolithiasis: A Case Report

Cornelia de Lange syndrome (CdLS) is a rare genetic disorder characterized by a distinctive facial appearance, growth/cognitive retardation, developmental delay, skeletal malformation, hypertrichosis, and other abnormalities. Patients with mild CdLS have less severe phenotypes, while retaining representative facial features. Mutations in the genes NIPBL, SMC1A, SMC3, HDAC8, and RAD21 have been associated with CdLS, with mutations in NIPBL accounting for approximately 60% of cases. Herein, we present a case of CdLS accompanied by cholelithiasis and nephrolithiasis. A 9-year-old Korean boy presented with vomiting and abdominal pain. Abdominal ultrasonography revealed several gallstones and renal stones. Extracorporeal shock wave lithotripsy failed; therefore, cholecystectomy and nephrolithotomy were performed. Postoperative stone composition analysis revealed calcium oxalate as the primary component. CdLS was suspected based on the characteristic appearance and physical examination, with genetic testing confirming an NIPBL gene mutation. Simultaneous CdLS, cholelithiasis, and nephrolithiasis requires careful management and treatment tailored to each patient's specific needs and challenges.

A blood-based multi-omic landscape for the molecular characterization of kidney stone disease

Kidney stone disease (KSD, also named renal calculi, nephrolithiasis, or urolithiasis) is a common urological disease entailing the formation of minerals and salts that form inside the urinary tract, frequently caused by diabetes, high blood pressure, hypertension, and monogenetic components in most patients. 10% of adults worldwide are affected by KSD, which continues to be highly prevalent and with increasing incidence. For the identification of novel therapeutic targets in KSD, we adopted high-throughput sequencing and mass spectrometry (MS) techniques in this study and carried out an integrative analysis of exosome proteomic data and DNA methylation data from blood samples of normal and KSD individuals. Our research delineated the profiling of exosomal proteins and DNA methylation in both healthy individuals and those afflicted with KSD, finding that the overexpressed proteins and the demethylated genes in KSD samples are associated with immune responses. The consistency of the results in proteomics and epigenetics supports the feasibility of the comprehensive strategy. Our insights into the molecular landscape of KSD pave the way for a deeper understanding of its pathogenic mechanism, providing an opportunity for more precise diagnosis and targeted treatment strategies for KSD.

Intensity-Specific Physical Activity Measured by Accelerometer, Genetic Susceptibility, and the Risk of Kidney Stone Disease: Results From the UK Biobank

RATIONALE & OBJECTIVE

Kidney stone disease (KSD), a significant health care problem within both developed and developing countries, has been associated with genetic risk factors. An association between physical activity and KSD risk also has been hypothesized, but studies have yielded inconsistent findings. This study investigated the association between the intensity of physical activity and the incidence of KSD accounting for genetic risk.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

A total of 80,473 participants from the UK Biobank Study.

EXPOSURE

Physical activity levels, including total physical activity (TPA), moderate-to-vigorous intensity physical activity (MVPA), and light-intensity physical activity (LPA), were measured using accelerometers and quantified using a machine learning model. A polygenic risk score (PRS) for KSD was also constructed.

OUTCOME

Individuals with KSD were identified using the International Classification of Diseases, Tenth Revision (ICD-10), and procedure codes for KSD surgery.

ANALYTICAL APPROACH

A Fine and Gray survival model was used to estimate the associations of incident KSD with TPA, MVPA, LPA, and PRS (as categorical variables). Restricted cubic splines were used to examine potential nonlinear associations within the fully adjusted models.

RESULTS

During an average follow-up of 6.19 years, 421 participants developed KSD. Participants in the highest quartiles of TPA, MVPA, and LPA had lower adjusted rates of KSD compared with those in the lowest quartiles: HR, 0.50 (95% CI, 0.44-0.56), 0.57 (95% CI, 0.51-0.64), and 0.66 (95% CI, 0.59-0.74), respectively. TPA, MVPA, and LPA were associated with a lower risk of KSD in participants with low and high genetic predisposition for KSD.

LIMITATIONS

Selection bias as participants who provided accelerometry data may have been more adherent to health care.

CONCLUSIONS

Physical activity was negatively associated with the risk of KSD, regardless of the genetic risk. Future large studies are warranted to confirm and explain the mechanisms underlying these associations.

PLAIN-LANGUAGE SUMMARY

The association between the intensity of physical activity (PA) and the incidence of kidney stone disease (KSD) after accounting for genetic risk is unclear. We conducted a comprehensive prospective cohort study utilizing participants from the UK Biobank to assess the intensity of PA using accelerometers. Our study findings indicated that greater total PA, moderate-to-vigorous-intensity PA, and light-intensity PA were each associated with a lower risk of KSD irrespective of an individual's genetic risk. Our study informs the understanding of risk factors for KSD.

Safety and efficacy of a polyherbal formulation from traditional Persian medicine in patients with calcium kidney stones: A randomized, double-blinded clinical trial

Background

10%-15% of the world's population suffers from kidney stones. Nearly 50% increase was observed in diagnosing and treating nephrolithiasis in the last decades. Effective medical treatment for the disease is not yet well established. Moreover, there is an increasing global demand to manage diseases using complementary and alternative medicine. This study aimed to formulate and assess the safety and efficacy of a multi-ingredient formulation from traditional Persian medicine (TPM) known as Mofatet powder in patients suffering from calcium kidney stones.

Materials and Methods

The aqueous extract of Mofatet powder was prepared, freeze-dried, and formulated as capsules. 26 patients in the drug group and 25 patients in the placebo group used 500 mg capsules of the drug/placebo twice daily for 5 weeks. Ultrasonography/kidney, ureter and bladder imaging, urine analysis, and biochemical parameters were evaluated before and after the intervention.

Results

The imaging results showed a 60.73% decrease (P < 0.001) in stone size in the drug group. Moreover, the urinary calcium decreased (P = 0.02) and the urinary magnesium increased (P < 0.001) in the drug group. No remarkable changes were observed in the placebo group in these parameters. No significant effect was observed in aspartate transaminase, alanine transaminase, serum creatinine, and blood urea nitrogen levels in none of the groups.

Conclusion

This study suggests that Mofatet powder was effective in reducing calcium kidney stones size with no potential nephro/hepatotoxicity. After confirming these results in larger clinical trials with longer duration, this formulation can be considered a treatment for nephrolithiasis.

Popular Diets and Kidney Stones

Popular diets often influence dietary patterns, which have different implications for kidney stone risk. Despite the wide variety of popular diets, some general principles can be gleaned from investigating their potential impact on nephrolithiasis. Plant-based diets, including Dietary Approaches to Stop Hypertension, Mediterranean, flexitarian, and vegetarian diets, may protect against nephrolithiasis when they consist largely of unprocessed plant foods, while carbohydrate-restricted diets (including high-protein diets and the ketogenic diet) may raise kidney stone risk. Patients should be advised to consume a diet rich in whole plants, particularly fruits and vegetables, and minimize their consumption of animal proteins. Accompanying fruits and vegetables that are higher in oxalate content with more water and some dairy intake may also be useful. (We address the oxalate content of fruits and vegetables further below). Calcium consumption is an important component of decreasing the risk of kidney stones, as higher dietary calcium from dairy or nondairy sources is independently associated with lower kidney stone risk. Patients should also be advised to be conscious of fat intake, as fat in the intestinal lumen may complex with calcium and therefore increase urinary oxalate excretion. Finally, patients should avoid consumption of processed foods, which often contain added fructose and high sodium content, two factors that increase kidney stone risk.

Tubular Diseases and Stones Seen From Pediatric and Adult Nephrology Perspectives

The tubular system of the kidneys is a complex series of morphologic and functional units orchestrating the content of tubular fluid as it flows along the nephron and collecting ducts. Renal tubules maintain body water, regulate electrolytes and acid-base balance, reabsorb precious organic solutes, and eliminate specific metabolites, toxins, and drugs. In addition, decisive mechanisms to adjust blood pressure are governed by the renal tubules. Genetic as well as acquired disorders of these tubular functions may cause serious diseases that manifest both in childhood and adulthood. This article addresses a selection of tubulopathies and the underlying pathomechanisms, while highlighting the important differences in pediatric and adult nephrology care. These range from rare monogenic conditions such as nephrogenic diabetes insipidus, cystinosis, and Bartter syndrome that present in childhood, to the genetic and acquired tubular pathologies causing hypertension or nephrolithiasis that are more prevalent in adults. Both pediatric and adult nephrologists must be aware of these conditions and the age-dependent manifestations that warrant close interaction between the two subspecialties.

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

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

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.

Diagnosis and Management of Nephrolithiasis in Children

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

Metabolic and Genetic Evaluation in Children with Nephrolithiasis

OBJECTIVE

To evaluate metabolic and genetic abnormalities in children with nephrolithiasis attending a referral center in North India.

METHODS

The patients aged 1-18 y old with nephrolithiasis underwent biochemical evaluation and whole-exome sequencing. The authors evaluated for monogenic variants in 56 genes and compared allele frequency of 39 reported polymorphisms between patients and 1739 controls from the GenomeAsia 100 K database.

RESULTS

Fifty-four patients, aged 9.1 ± 3.7 y were included. Stones were bilateral in 42.6%, familial in 33.3%, and recurrent in 25.9%. The most common metabolic abnormalities were hypercalciuria (35.2%), hyperoxaluria (24.1%), or both (11.1%), while xanthinuria (n = 3), cystinuria (n = 1), and hyperuricosuria (n = 1) were rare. Exome sequencing identified an etiology in 6 (11.1%) patients with pathogenic/likely pathogenic causative variants. Three variants in MOCOS and one in ATP7B were pathogenic; likely pathogenic variants included MOCOS (n = 2), AGXT, and SLC7A9 (n = 1, each). Causality was not attributed to two SLC34A1 likely pathogenic variants, due to lack of matching phenotype and dominant family history. Compared to controls, allele frequency of the polymorphism TRPV5 rs4252402 was significantly higher in familial stone disease (allele frequency 0.47 versus 0.53; OR 3.2, p = 0.0001).

CONCLUSION

The chief metabolic abnormalities were hypercalciuria and hyperoxaluria. A monogenic etiology was identified in 11% with pathogenic or likely pathogenic variants using a gene panel for nephrolithiasis. Heterozygous missense variants in the sodium-phosphate cotransporter SLC34A1 were common and required evaluation for attributing pathogenicity. Rare polymorphisms in TRPV5 might increase the risk of familial stones. These findings suggest that a combination of metabolic and genetic evaluation is useful for determining the etiology of nephrolithiasis.

Childhood diabetes mellitus and early-onset kidney diseases later in life: a nationwide population-based matched cohort study

BACKGROUND

The empirical evidence remains inconclusive for an association between diabetes mellitus (DM) in children and early-onset kidney disease later in life, and little is known about the effects of DM types (i.e., type 1 diabetes [T1DM] and type 2 diabetes [T2DM]) in childhood on type-specific kidney diseases. We aimed to evaluate the association of childhood DM with overall and type-specific early-onset kidney diseases later in life.

METHODS

The population-based matched cohort study included 9356 individuals with DM (T1DM: 8470, T2DM: 886) diagnosed in childhood (&lt; 18 years) who were born between 1977 and 2016, and 93,560 individuals without DM matched on sex and year of birth in Denmark. The main outcomes were overall and type-specific early-onset kidney diseases. The follow-up period of all included participants was from the date of DM diagnosis in the exposure group until the first diagnosis of kidney disease, emigration, or 31 December 2018, whichever came first.

RESULTS

During a median follow-up of 13 years, children with DM had a 154% increased risk of early-onset kidney diseases than children without DM (adjusted hazard ratios 2.54, 95% confidence intervals 2.38-2.72), and T1DM (2.48, 2.31-2.67) and T2DM (2.75, 2.28-3.31) showed similar results. Children with DM also had a higher risk of multiple specific kidney diseases including glomerular diseases, renal tubulo-interstitial diseases, renal failure, and urolithiasis. The risks of type-specific kidney diseases including glomerular diseases and renal failure tended to be higher for children with T2DM (glomerular diseases: 5.84, 3.69-9.24; renal failure: 14.77, 8.53-25.59) than those with T1DM (glomerular diseases: 3.14, 2.57-3.83; renal failure: 8.24, 6.66-10.20).

CONCLUSIONS

Children with DM had a higher increased risk of early-onset overall and specific kidney diseases later in life. Early prevention and treatment of both T1DM and T2DM in childhood may significantly reduce the risk of kidney diseases later in life.

The Impact of Water and Other Fluids on Pediatric Nephrolithiasis

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

The correlation between promoter hypermethylation of VDR, CLDN, and CasR genes and recurrent stone formation

Objectives

Recurrent Kidney stone formation is a main medical problem imposing a significant burden on both healthcare and the economy worldwide. Environmental and genetic factors have been linked to a bigger risk of kidney stone formation. We aim to assess the role of methylation on recurrent stone formation in three target genes.

Methods

We aimed to check the association between promoter hypermethylation vitamin D receptor (VDR), calcium-sensing receptor (CaSR), and claudin 14 (CLDN14) genes in recurrent kidney stones. We enrolled 30 consecutive recurrent kidney stone formers (age 18–60 years) (cases) and 30 age and gender-matched controls.3. To identify promoter methylation, two target regions from each candidate gene were bisulfited after blood collection and DNA extraction. Methylation quantification was done through methylation-specific high resolution melting (MS-HRM).

Results

The mean age of the patients and controls (mean ± SD) was 49.58 ± 14.23 years and BMI 36.12 ± 2.72. The methylation status in all six target regions was meaningfully different between the stone-former group and controls when methylation was considered in three clusters of unmethylated, methylated, and hypermethylated. A higher effect in VDR and CLDN was observed compare to CasR (p-value < 0.001, and < 0.005 versus p-value < 0.256).

Conclusions

Methylation as an important epigenetic mechanism should be considered more in recurrent stone formations. Promoter hypermethylation of VRD and CLDN genes may have an essential role in recurrent kidney stones formations.

Pediatric Mineral and Bone Disorder of Chronic Kidney Disease and Cardiovascular Disease

Chronic kidney disease is common and causes significant morbidity including shortened lifespans and decrease in quality of life for patients. The major cause of mortality in chronic kidney disease is cardiovascular disease. Cardiovascular disease within the chronic kidney disease population is closely tied with disordered calcium and phosphorus metabolism and driven in part by renal bone disease. The complex nature of renal, bone, and cardiovascular diseases was renamed as mineral and bone disorder of chronic kidney disease to encompass how bone disease drives vascular calcification and contributes to the development of long-term cardiovascular disease, and recent data suggest that managing bone disease well can augment and improve cardiovascular disease status. Pediatric nephrologists have additional obstacles in optimal mineral and bone disorder of chronic kidney disease management such as linear growth and skeletal maturation. In this article, we will discuss cardiovascular and bone diseases in chronic kidney disease and end-stage kidney disease patients with a focus on pediatric issues and concerns.

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.

The genetics of kidney stone disease and nephrocalcinosis

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

Fructose-Rich Diet Is a Risk Factor for Metabolic Syndrome, Proximal Tubule Injury and Urolithiasis in Rats

Excessive consumption of fructose (FR) leads to obesity, metabolic syndrome (MS) and insulin resistance, which are known risk factors for kidney stones. The epidemiological study has suggested the association between fructose consumption and urolithiasis, but the precise mechanism is still not well understood. Male Wistar rats were assigned for 8 weeks to three groups with different FR content in diet: RD (n = 5)-regular diet with a FR < 3%; F10 (n = 6)-regular diet with an addition of 10% Fr in drinking water; F60 (n = 5)-60% FR as a solid food. Serum concentration of FR, creatinine (Cr), insulin (Ins), triglycerides (Tg), homocysteine (HCS), uric acid (UA), calcium (Ca), phosphate (Pi), magnesium (Mg) and sodium (Na) were measured. Based on 24 h urine collection the following tests were performed: urine pH, proteinuria (PCR), excretion of N-Acetyl-(D)-Glucosaminidase (NAG), monocyte chemoattractant protein (MCP-1), uric acid (uUAEx), phosphate (uPiEx), calcium (uCaEx), magnesium (uMgEx) and sodium (uNaEx). The creatinine clearance (CrCl) was calculated. Calcium deposits in kidney sections were examined using hematoxylin and eosin (HE) and von Kossa stains. The rats on F10 and F60, as compared to the RD diet, showed a tendency for lower CrCl, higher HCS level and some features of MS as higher Ins and TG levels. Interestingly, F10 (fluid) versus F60 (solid) diet led to higher serum Ins levels. F10 and F60 versus RD demonstrated higher urinary excretion of MCP-1 and NAG which were suggestive for inflammatory injury of the proximal tubule. F10 and F60 as compared to RD showed significantly lower uUAEx, although there were no differences in clearance and fractional excretion of UA. F60 versus RD induced severe phosphaturia (>30×) and natriuria (4×) and mild calciuria. F10 versus RD induced calciuria (3×), phosphaturia (2×) and mild natriuria. Calcium phosphate stones within the tubules and interstitium were found only in rats on FR diet, respectively, in two rats from the F10 group and another two in the F60 group. The rats which developed stones were characterized by significantly higher serum insulin concentration and urinary excretion of calcium and magnesium. A fructose-rich diet may promote development of calcium stones due to proximal tubule injury and metabolic syndrome.

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.

Twinkle artifact in renal ultrasound, is it a solid point for the diagnosis of renal stone in children?

Background: Twinkle artifact, also known as color Doppler comet-tail artifact, occurs behind very strong, granular, and irregular reflecting interfaces such as crystals, stones, or calcification. This is visualized as a random mixture of red and blue pixels in the high-frequency shift spectrum located deep to the interface. Study results have suggested that the sonographic twinkling artifact may aid in the detection of renal stones with a variety of reference standard imaging modalities, including abdominal radiography, excretory urography, gray-scale sonography, and CT. Material and methods: Our retrospective observational study included children who had undergone abdomen/renal ultrasound for kidneys stones in our radiology department between 2013 and 2019. Presence of the twinkle artifact, and stone numbers and sizes were documented. CT examinations done <3 months prior to or after US were retrospectively assessed to confirm the presence of kidney stones as a reference standard. Results: Thirty-three abdominal renal US scans of 33 patients (21 males, 12 females) fulfilled the entry criteria. The interval between the US and CT was <3 months for all patients. The median overall age of the patients was 4 years (IQR: 3.125, range: 1- 165 months), The median number of days between the US and CT was 13 (IQR: 26, range: 0-81 days). US detected 33 hyperechoic foci suspected to be stones; 26 were confirmed as true positive (i.e. showed the twinkle artifact and were seen in CT), 4 were false positive (showed the twinkle artifact but were not seen in CT), and 3 were false negative (did not show the twinkle artifact but were seen in CT). The overall median stone size was 2 mm in the right kidney, and 5 mm in the left kidney (IQR: 6,11 mm), respectively. Twinkle artifact sensitivity was found to be 89.7% (95% CI 39.574%-90%). The twinkle artifact was assessed in all true-positive stones, determining a relatively high PPV of 26/29 (86.7%) for the twinkle artifact. The twinkle artifact was not dependent on stone size. Specificity for the twinkle artifact could not be calculated due to a lack of true negatives. Conclusion: The twinkle artifact is a sensitive US tool for detecting pediatric kidney and ureter stones, but with a small risk of false positive findings.

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

INTRODUCTION

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

MATERIAL AND METHOD

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

RESULTS

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

CONCLUSION

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

Age-Specific Excretion of Calcium, Oxalate, Citrate, and Glycosaminoglycans and Their Ratios in Healthy Children and Children with Urolithiasis

We analyzed children with urolithiasis with age- and gender-matched healthy children. Calcium (mmol/mmol creatinine) and the calcium/citrate ratio (mol/mmol) are the only variables that differentiate children before puberty from healthy children (ROC analysis confirmed only calcium/citrate as a significant variable with cut-off value > 0.84). Peri-pubertal children are distinguished from age- and gender-matched healthy children by the following variables: citrate (mmol/mol creatinine), calcium/citrate (mol/mmol), oxalate/glycosaminoglycans (mmol/g), oxalate/citrate ratios (mmol/mmol) and oxalate/(citrate × glycosaminoglycans) (mol oxalate × mol creatinine)/(mol citrate × g glycosaminoglycans). All variables were confirmed by ROC analysis with cut-off values ≤ 327.87, >1.02, >11.24, >0.12 and >0.03, respectively. These results indicate a different risk of urinary stones development before puberty vs. pubertal/postpubertal children and increasing importance (deficiency) of citrate and glycosaminoglycans in such children. J48 classifier confirmed the importance of the oxalate/(citrate × glycosaminoglycans) and the calcium/citrate ratios (Ox/Cit × GAG 0.22 and Cit/GAG 0.612) with the practically applicable classification tree for distinguishing between pubertal/postpubertal children with urolithiasis with age- and gender-matched healthy children.

Therapeutic ureteroscopy for urolithiasis in children younger than 60 months of age

PURPOSE

The management of urinary tract calculi has evolved dramatically in children with the development of smaller and more durable endoscopic equipment. The indications for therapeutic ureteroscopy in children have significantly expanded with the availability of smaller caliber endoscopes and Holmium:YAG laser. In this paper, we review our experience of the management of urolithiasis and report outcomes of therapeutic ureterorenoscopy (URS) in children younger than 60 months.

METHODS

We retrospectively reviewed the inpatient, outpatient records, and imaging data of our hospital, of all children ≤ 60 months of age undergoing URS for the treatment of urinary stones.

RESULTS

During the study period; 77 children, mostly male (70.1%) presenting with a single calculus and a mean age of 28.97 ± 2.44 months underwent therapeutic URS. A majority of children (71.4%) had lower or mid-ureteric calculi. Pre URS double J (DJ) stenting was necessary for 21 (27.2%) children. A total of 24 (31.1%) children needed ureteric dilatation before the ureteroscopy. Post URS DJ stenting was necessary in 41 (53.2%) children. Stents were retrieved within 10 days of the procedure. Stone clearance rate following a single-stage URS procedure was 94.8%, and 4 (5.2%) children needed additional shockwave lithotripsy (SWL) to achieve stone clearance. Overall complication rate including hematuria and fever was 12.9% (10 patients).

CONCLUSION

Therapeutic ureterorenoscopy in the management of ureteric and selective renal pelvic calculi is safe and effective. It can be considered as the first-line therapy in young children.

Urolithiasis in second-generation immigrant children younger than 18 years of age in Sweden

AIM

To compare incidence of urolithiasis in second-generation immigrant children aged 0-17 years to children of Swedish-born parents.

METHODS

A nationwide study of individuals residing in Sweden. Urolithiasis was defined as having at least one registered diagnosis of urolithiasis in the Swedish National Patient Register between January 1, 1998 and December 31, 2015. Cox regression analysis was used to estimate the relative risk (hazard ratios (HR) with 95% confidence intervals (CI)) of incident urolithiasis compared to individuals with Swedish-born parents. The models were stratified by sex and adjusted for age, co-morbidities and sociodemographic status of parents.

RESULTS

Totally, 1653 incident cases of urolithiasis were registered, 658 boys and 995 girls, with a mean annual incidence per 100 000 person-years for children with Swedish-born parents of 4.0 (95% CI 3.7-4.3) in boys and 6.7 (95% CI 6.2-7.2) in girls, and for children with foreign-born parents of 5.3 (95% CI 5.1-5.4) in boys and 7.2 (95% CI 6.9-7.4) in girls. The fully adjusted HRs of urolithiasis in second-generation immigrants were non-significant, in boys (1.20, 95% CI 0.99-1.46) and girls (0.95, 95% CI 0.80-1.12).

CONCLUSION

The risk of urolithiasis in second-generation immigrants was not significantly different from that of children with Swedish-born parents.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Nephrolithiasis: Approach to Diagnosis and Management

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

Rising occurrence of hypocitraturia and hyperoxaluria associated with increasing prevalence of stone disease in calcium kidney stone formers

OBJECTIVE

To evaluate metabolic risk factors in calcium kidney stone formers from two different decades, comparing changes in metabolic profiles over time.

METHODS

A retrospective analysis was performed of calcium kidney stone formers who underwent metabolic evaluation of urolithiasis with 24-hour urine collections at a single institution. There were 309 patients evaluated from 1988 to 1994 (Group A), and 229 patients from 2007 to 2010 (Group B). A comparison between both groups was performed to assess changes in demographics and in metabolic stone profiles.

RESULTS

Comparing Group A to Group B, the percentage of females increased from 43 to 56%, obese patients (BMI ≥ 30) increased from 22 to 35%, and patients ≥ 50 years increased from 29 to 47% (all p < 0.005). A greater percentage of patients had hypocitraturia in the recent cohort (46-60%, p = 0.001), with hypocitraturia significantly more frequent in obese patients (p = 0.005). Hyperoxaluria was also increased in Group B compared to Group A (23-30% p = 0.07), a finding that was significant in males (32-53%, p = 0.001).

CONCLUSIONS

Urolithiasis has increased in females, obese, and older patients, consistent with population-based studies. We report a rising incidence of hypocitraturia and hyperoxaluria in the contemporary cohort, particularly in obese patients and in males, respectively. Further studies are needed to better characterize the metabolic changes corresponding to the increase in stone disease.

Renal Papillary Mapping and Quantification of Randall's Plaque in Pediatric Calcium Oxalate Stone Formers

Introduction: Randall's plaque (RP) with attached stones is recognized as a primary mechanism for stone formation in adult calcium oxalate stone formers (CaOx SFs). The role of RP in pediatric stone pathogenesis is unknown, with no reported studies to date. The purpose of this study is to investigate renal papillary abnormalities and quantify RP in pediatric CaOx SFs. Methods: Eight pediatric CaOx SFs underwent ureteroscopy for symptomatic urolithiasis. The collecting system was mapped using a digital ureteroscope. Video for each patient was then reviewed using a retrograde pyelogram to confirm the location of each papilla. A single investigator (N.L.M.) reviewed the video to quantify RP. Each papilla was graded as having mild, moderate, or severe amount of RP. Patient history was recorded. Results: An average of nine papillae were mapped per patient. RP was present in 100% of patients and in 88.8% (64/72) of all papillae examined. When present, RP was uniformly distributed throughout the kidney without preferential distribution to a region or pole. The amount of RP on the papillae was graded as mild in 60%, moderate in 20.8%, and severe in 8.3%. The mean fractional RP coverage ranged from 0.39% to 9.34%. No correlation was found between the amount of plaque and age at first stone episode or number of prior stone episodes (p = 0.84). Attached stones were rare (1/8 patients). The two patients with severe RP had a small amount of calcium phosphate in their stone analysis. Conclusions: RP is common in pediatric CaOx SFs. Compared with adult CaOx SFs wherein up to 75% of stones are found attached to RP, attached stones were rare. The significance of these findings in the pathogenesis of pediatric stone formation remains unclear and will require longer term follow-up.

Urolithiasis, growth and blood pressure in childhood: A case-control study

BACKGROUND & AIMS

Kidney stone is a life-threatening disease with subsequent complications, especially in children who overtake this disease in early ages. This study assessed the effect of kidney stone history on current blood pressure and growth parameters of children.

METHODS

A two hundred children with (n = 100) and without (n = 100) a history of urolithiasis from Pediatric Urology clinics at the Aliasghar hospital, Tehran, Iran, participated in this case-control study. Several demographic data, height, weight, body mass index (BMI), BMI for age and blood pressure index were measured as the primary outcomes.

RESULTS

type of birth and infancy feeding, carbohydrate and energy intake were significantly different between the two groups (P = 0.008, 0.002, 0.03 and < 0.001 respectively). Ordinal logistic regression analysis showed that the current weight (P = 0.001) and BMI for age (P = 0.02) of the stone formers were lower than the non-stone formers, while no significant association found between the blood pressure or current height and the history of urolithiasis.

CONCLUSION

Our findings suggest that childhood urolithiasis has no significant effect on growth failure and blood pressure in childhood but it has a little impact on weight and BMI for age in older ages.

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

INTRODUCTION

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

DISCUSSION

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

CONCLUSIONS

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

Pediatric Nephrolithiasis: Risk Factors, Evaluation, and Prevention

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

National Imaging Trends of Recurrent Pediatric Urolithiasis

OBJECTIVES

The aim of this study was to examine computed tomography (CT) and ultrasound (US) utilization trends in incident and prevalent pediatric emergency department (ED) urolithiasis patients before and after imaging guideline release.

METHODS

We reviewed imaging modalities for children with 2 or more ED encounters between January 1, 2006, and September 1, 2013, for urolithiasis using the Pediatric Health Information System database. Z scores compared the proportion of patient encounters receiving CT and US before (January 1, 2006, to December 31, 2010) and after (January 1, 2011, to September 1, 2013) the release of imaging guidelines. McNemar test for paired proportions compared the percentage of US and CT use between initial versus subsequent visits. Piecewise logistic regression was used to determine the probability of US use and CT use over time before and after the implementation of imaging guidance.

RESULTS

Analysis was completed on 2041 patients with 4930 unique encounters for urolithiasis. During 1758 encounters (35.7%), CT was performed initially. Ultrasound was performed 1585 times (32.2%). Fourteen percent fewer CT procedures were performed during first urolithiasis visits after guideline release (P < 0.01), whereas US use increased by 15% (P < 0.01). Fewer CT procedures were performed at later visits compared with the first (P < 0.05), and US was used more during second or later visits than the first (P < 0.05).

CONCLUSIONS

Medical providers at large academic pediatric EDs have decreased use of CT and increased use of US over the study time frame to diagnose urolithiasis and are now similar during initial visits (US 36.4% vs CT 36.2%, P = 0.94). Physicians are still more likely to use US as the initial urolithiasis imaging modality during second and later encounters.

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

BACKGROUND

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

OBJECTIVE

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

RESULTS

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

CONCLUSIONS

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

Evaluation of the composition of urinary tract stones in children from the Inner Western Anatolian Region in Turkey

OBJECTIVE

Pediatric urolithiasis is a globally growing problem. The composition and frequency of urinary tract stones vary not only among different countries, but across various regions in a country. Hence, we aimed to identify the types and frequencies of urinary tract stones in children from our region (Inner Western Anatolian part of Turkey), and to compare our findings with the results from other regions in our country.

MATERIAL AND METHODS

In this retrospective analysis of 53 pediatric urolithiasis cases that were treated in our hospital between 2009 and 2019, the demographic data, clinical course, radiological and metabolic findings, the recurrence rate, and the composition of the stones were evaluated.

RESULTS

The mean age of the patients was 5.9±4.6 (0.5-18) years, and there were 30 (56.6%) girls and 23 (43.4%) boys. An analysis of the composition of the stones revealed that the majority (85%) consisted of calcium oxalate. The highest risk of recurrence and the need for multiple shockwave lithotripsy (SWL) sessions or surgical intervention appeared to be related with the presence of whewellite stones, which are the most challenging stones in childhood.

CONCLUSION

According the study results, the urinary stone types vary across different regions in our country, and the frequency of uric acid stones decreased going westward, while the frequency of oxalate stones increased. We conclude that this difference in the frequency of the type of urinary stones might reflect the regional dietary habits. Regional frequency and etiology studies for the types of urolithiasis may facilitate the approach to the treatment of urolithiasis.

Stone recurrence among childhood kidney stone formers: results of a nationwide study in Iceland

OBJECTIVES

To examine the stone recurrence rate among childhood kidney stone formers in the Icelandic population.

MATERIALS AND METHODS

We retrospectively examined kidney stone recurrence in a recently reported population-based sample of 190 individuals who experienced their first stone before 18 years of age in the period 1985-2013. Of these 190 individuals, 112 (59%) were females and the median (range) age at the incident stone diagnosis was 15.0 (0.2-17.9) years. Stone recurrence was defined as an acute symptomatic episode with imaging confirmation or self-reported stone passage, new stone detected by imaging in asymptomatic patients, and suspected clinical stone episode without verification. The Kaplan-Meier method was used to assess stone-free survival and the Chi-square, Fisher's exact, Wilcoxon rank-sum and the log-rank tests to compare groups.

RESULTS

A total of 68 (35%) individuals experienced a second stone event, 1.7 (0.9-18.9) years after the initial diagnosis. The recurrence rate was 26%, 35%, 41% and 46% after 5, 10, 15 and 20 years of follow-up, respectively. The 5-year recurrence rate increased with time and was 9%, 24% and 37% in the periods 1985-1994, 1995-2004 and 2005-2013, respectively (P = 0.005). No difference in stone recurrence was observed between the sexes (P = 0.23).

CONCLUSIONS

In our population-based sample of childhood kidney stone formers, the stone recurrence rate is similar to that reported for adults. The observed rise in stone recurrence with time may be related to closer patient follow-up in recent years or increased stone risk in general.

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

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

Acoustic shadowing in pediatric kidney stone ultrasound: a retrospective study with non-enhanced computed tomography as reference standard

BACKGROUND

The usefulness of acoustic shadowing as a feature of pediatric kidney stone ultrasound (US) may be underestimated.

OBJECTIVE

The hypothesis was that the majority of stones in children have acoustic shadowing and that its specificity is high (>90%) in pediatric kidney stones.

MATERIALS AND METHODS

Our retrospective observational study included children who had undergone abdominal non-enhanced computed tomography (CT) for kidney stones in a pediatric renal stone referral centre between 2015 and 2016. US examinations prior to CT were retrospectively assessed for US features such as acoustic shadowing, twinkle artifact and stone size. These features were compared to CT as reference standard.

RESULTS

Thirty-one patients (median age: 13 years, range: 1-17 years) with 77 suspected kidney stones were included. The median stone size was 5 mm (interquartile range [IQR]: 5 mm). For acoustic shadowing, sensitivity was 70% (95% confidence interval [CI] 56-80%) and specificity was 100% (95% CI 56-100%). All kidney stones with a diameter ≥9 mm demonstrated shadowing. Sensitivity for twinkle artifact was 88% (95% CI 72-96%), but specificity for twinkle artifact could not be calculated due to the lack of true negatives. All false-positive stones on US demonstrated twinkle artifact, but none showed shadowing.

CONCLUSION

Acoustic shadowing was demonstrated in the majority of pediatric kidney stones. Specificity was high, but this was not significant. Twinkle artifact is a sensitive US tool for detecting (pediatric) kidney calculi, but with a risk of false-positive findings.

Increased body fatness adversely relates to 24-hour urine pH during childhood and adolescence: evidence of an adipo-renal axis

BACKGROUND

Reduced net acid excretion (NAE) capacity indicates a decrease in renal function. This reduction manifests as a disproportionally low 24-h urine pH in relation to the sum of actually excreted ammonium and titratable acidity by the kidney.

OBJECTIVE

The aim of this study was to test the hypothesis that higher body fatness is one determinant of kidney function impairment with a lowered urine pH even at a young age.

METHODS

NAE, pH, urea, and creatinine were measured in 24-h urine samples from 524 healthy children and adolescents (aged 6-17 y) participating in the DOrtmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study. Body fatness was assessed anthropometrically by body mass index-standard deviation score (BMI-SDS), fat mass index (FMI), body fat % (BF%), and waist circumference (WC). Multivariable linear and mixed linear regressions were used to examine cross-sectionally (n = 524 urine samples; age groups: 6-8, 9-11, 12-14, 15-17 y) and longitudinally (n = 1999 urine samples) the associations of body fatness with 24-h urine pH as the outcome variable, respectively.

RESULTS

After adjusting for the kidneys' total net acid load (24-h urinary NAE) and further relevant covariates, FMI showed significant inverse relations with urinary pH in all 4 age groups, and BMI-SDS, BF%, and WC each in 3 out of these 4 groups (P ≤ 0.02). Longitudinal results substantiated these interindividual relations and further showed intraindividual increases in body fatness to be paralleled by urine pH decreases (P ≤ 0.0002).

CONCLUSIONS

Independent of underlying acid load, an early increase in body fatness is associated with increased free proton excretion, and thus with a decline in the kidney's acid excretion function, which could potentiate the risk of renal nephrolithiasis.

Hydroxycitrate: a potential new therapy for calcium urolithiasis

Alkali supplements are used to treat calcium kidney stones owing to their ability to increase urine citrate excretion which lowers stone risk by inhibiting crystallization and complexing calcium. However, alkali increases urine pH, which may reduce effectiveness for patients with calcium phosphate stones and alkaline urine. Hydroxycitrate is a structural analog of citrate, widely available as an over-the-counter supplement for weight reduction. In vitro studies show hydroxycitrate has the capacity to complex calcium equivalent to that of citrate and that it is an effective inhibitor of calcium oxalate monohydrate crystallization. In fact, hydroxycitrate was shown to dissolve calcium oxalate crystals in supersaturated solution in vitro. Hydroxycitrate is not known to be metabolized by humans, so it would not be expected to alter urine pH, as opposed to citrate therapy. Preliminary studies have shown orally ingested hydroxycitrate is excreted in urine, making it an excellent candidate as a stone therapeutic. In this article, we detail the crystal inhibition activity of hydroxycitrate, review the current knowledge of hydroxycitrate use in humans, and identify gaps in knowledge that require appropriate research studies before hydroxycitrate can be recommended as a therapy for kidney stones.

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

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

Phosphaturia in kidney stone formers: Still an enigma

Calcium kidney stones are common worldwide. Most are idiopathic and composed of calcium oxalate. Calcium phosphate is present in around 80% and may initiate stone formation. Stone production is multifactorial with a polygenic genetic contribution. Phosphaturia is found frequently among stone formers but until recently received scant attention. This review examines possible mechanisms for the phosphaturia and its relevance to stone formation from a wide angle. There is a striking lack of clinical data. Phosphaturia is associated, but not correlated, with hypercalciuria, increased 1,25 dihydroxy-vitamin D [1,25 (OH)₂D], and sometimes evidence of disturbances in proximal renal tubular function. Phosphate reabsorption in the proximal renal tubules requires tightly regulated interaction of many proteins. Paracellular flow through intercellular tight junctions is the major route of phosphate absorption from the intestine and can be reduced therapeutically in hyperphosphatemic patients. In monogenic defects stones develop when phosphaturia is associated with hypercalciuria, generally explained by increased 1,25 (OH)₂D production in response to hypophosphatemia. Calcification does not occur in disorders with increased FGF23 when phosphaturia occurs in isolation and 1,25 (OH)₂D is suppressed. Candidate gene studies have identified mutations in the phosphate transporters, but in few individuals. One genome-wide study identified a polymorphism of the phosphate transporter gene SLC34A4 associated with stones. Others did not find mutations obviously linked to phosphate reabsorption. Future genetic studies should have a wide trawl and should focus initially on groups of patients with clearly defined phenotypes. The global data should be pooled.

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

Objective:

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

Methods:

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

Results:

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

Conclusions:

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

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

INTRODUCTION

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

MATERIAL AND METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSIONS

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