High incidence of kidney stones in Icelandic children

A population-based retrospective cohort study of surgical trends and outcomes of pediatric urolithiasis in Ontario, Canada (2002-2019)

INTRODUCTION

The worldwide incidence of pediatric urinary stone disease (PUSD) is increasing. However, there is no commensurate data on whether this translates to an increasing need for surgical intervention for PUSD, given the role of conservative management.

OBJECTIVE

We aimed to evaluate the trends and outcomes of clinically significant PUSD, using administrative databases to identify patients surgically treated for PUSD.

STUDY DESIGN

This retrospective population-based cohort study assessed the incidence and trends of surgically treated PUSD and outcomes in Ontario, Canada in patients <18 years of age who underwent their first PUSD procedure between 2002 and 2019 utilizing administrative databases held at the Institute of Clinical Evaluative Sciences (ICES). We assessed the incidence of surgically treated PUSD, demographics, initial surgical treatment and imaging modality, and risk factors for repeat intervention within 5 years. Statistical analyses summarized demographics, surgical trends, and logistic regression was used to identify risk factors for repeat surgical intervention.

RESULTS

We identified 1149 patients (mean age 11.3 years), with 59.6% older than 12 years. There was a decrease in the number of PUSD procedures performed per year that was close to statistical significance (p = 0.059) and a trend towards increased utilization of ureteroscopy (URS) compared with Shockwave Lithotripsy (SWL). In addition, there was a significant increase in the proportion of females surgically treated with PUSD (p = 0.001). In the 706 patients followed for 5 years, 17.7% underwent a repeat procedure within 6 months, while 20.4% underwent a repeat procedure from 6-months to 5 years. Renal stone location (OR 2.79, 95% confidence interval (CI) 1.62-4.80, p = 0.0002) and index SWL (OR 1.66, 95% CI 1.20-2.31, p = 0.0025) were risk factors for repeat surgical intervention within the first 6-months. There was an increasing utilization of ultrasound (US) compared to computerized tomography (CT) (p = 0.0008).

DISCUSSION

Despite the literature reporting increasing PUSD incidence, we observed a non-significant decrease in the number of surgical PUSD procedures performed. Exclusion of those treated conservatively may explain our results. The increase in the proportion of females treated reflects the narrowing gender gap in stone disease. A trend towards increased URS utilization was observed and re-intervention rates were similar to previous studies.

CONCLUSION

The overall rate of surgically treated PUSD did not show an increasing trend in Ontario, Canada from 2002 to 2019. URS was the most common surgical treatment modality, with a corresponding decline in SWL rates. PUSD was associated with a high surgical re-intervention rate within 6 months.

Clinical Toxicology of Vitamin D in Pediatrics: A Review and Case Reports

Intoxication of vitamin D is not a common case in pediatrics. Vitamin D supplements are sold as OTC drugs; however, there is a lack of public education about the permissible limits of vitamin D intake which may lead to vitamin D toxicity (VDT). This review aims to give insights to readers or practitioners about the clinical toxicology of vitamin D in pediatrics, which includes the mechanism of VDT, case reports, and the management of vitamin D poisoning. VDT refers to serum 25(OH)D levels, particularly when the level exceeds 100 ng/mL (250 nmol/L) or is defined as hypervitaminosis D. Hypercalcemia is a common condition of vitamin D toxicity. Vitamin D and its metabolites in moderate levels can induce hypercalcemia, as indicated by the elevation of osteoclastic bone resorption, the presence of calcium in renal tubules, intestinal calcium intake (through increased production of calcium-binding protein in enterocytes), and the decrease of parathyroid hormone synthesis. VDT in pediatrics can be managed by discontinuing vitamin D intake; using activated charcoal, furosemide, prednisone, and calcitonin; rehydration using intravenous sodium chloride 0.9%; and dextrose fluid therapy. It is important for parents to be more careful when providing vitamin D to their children.

Associations between IL-1RN variable number of tandem repeat, IL-1β (-511) and IL-1β (+3954) gene polymorphisms and urolithiasis in Uighur children of China

OBJECTIVE

Interleukin-1 (IL-1) is a pro-inflammatory cytokine which may be related to urolithiasis. Genetic polymorphisms of the interleukin-1beta (IL-1β) have been proposed as markers for urolithiasis in some areas. Due to the high incidence of urolithiasis in Uighur children (Xinjiang, China) and existence of ethnic difference, our aim is to explore the potential of IL-1 gene polymorphisms and urolithiasis among these children.

METHODS

Genomic DNA extracted from peripheral blood of 115 patients and 98 controls were used for genotype polymorphisms analyses. IL-1 receptor antagonist (IL- 1RN) gene variable number of tandem repeat (VNTR) gene polymorphisms were analyzed by PCR method. PCR-based restriction analysis was done for the IL-1β (-511) and IL-1β (+3954) gene polymorphisms by endonucleases Ava I and Taq I, respectively. The genotype distribution, allele frequencies, carriage rate, and haplotype frequencies were statistically analyzed.

RESULTS

No significant differences were observed in genotypic frequencies between pediatric urolithiasis patients and control group for IL-1RN gene (χ ²=1.906, p=0.605), IL-1β (-511) gene (χ ²=0.105, p=0.949), or IL-1β (+3954) gene (χ ²=3.635, p=0.169). There were yet no significant differences of the allele frequencies of IL-1RN VNTR gene (p=0.779), IL-1β (-511) gene (p=0.941), and IL-1β (+3954) gene (p=0.418) in the case and control groups, as well as the carriage rate and haplotype of them (all p>0.05).

CONCLUSIONS

The associations between IL-1RN VNTR, IL-1β (-511) and IL-1β (+3954) genes polymorphisms and urolithiasis were not significant in Uighur children. The results need to be confirmed in studies with larger population sample size, as well as in other ethnic groups.

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.

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 .

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

The idiopathic hypercalciuria reviewed. Metabolic abnormality or disease?

Idiopathic hypercalciuria (IH) is defined as that clinical situation in which an increase in urinary calcium excretion is observed, in the absence of hypercalcemia and other known causes of hypercalciuria. In recent years, its diagnosis in pediatric age has been more frequent because it has been known that it can debut with very different symptoms, in the absence of kidney stone formation. The discovery of genetic hypercalciuric stone-forming rats has allowed us to glimpse the pathophysiological mechanism of IH since they show many data in common with humans with IH as normal levels of blood calcium, intestinal calcium hyperabsorption, increased bone resorption and a defect in the renal tubular calcium reabsorption. In 1993, it was shown that in these animals there is an increase in the number of vitamin D receptors (VDR) in the intestine, which favors an increase in the functional capacity of calcitriol-VDR complexes that explains the increase in intestinal transport of calcium. The same happens at the bone level producing a greater resorption. In our opinion, IH is a 'metabolic anomaly' or, better, an inheritable constitutive metabolic characteristic. In this sense, what patients with IH would inherit is the availability of having a greater number of VDRs in their cells than those with normal urinary calcium excretion. IH cannot be considered a sensu stricto disease, so pharmacological treatment must be individualized.

Confounding risk factors and preventative measures driving nephrolithiasis global makeup

Nephrolithiasis is increasing in developed and developing countries at an alarming rate. With the global spike in kidney stone diseases, it is crucial to determine what risk factors are influencing the current global landscape for kidney stones. Our aims for this review are: to identity and analyze the four categories of risk factors in contributing to the global scale of stone formation: lifestyle, genetics, diet, and environment; and discuss preventative measures for kidney stone formation. We also performed data search through the published scientific literature, i.e., PubMed^® and found that there is a significant link between lifestyle and obesity with cases of calcium stones. Food and Agriculture Organization of the United Nations and World Health Organization factor indicators for dietary intake and obesity, along with climate data were used to create the projected total risk world map model for nephrolithiasis risk. Complete global analyses of nephrolithiasis deplete of generalizations is nearly insurmountable due to limited sources of medical and demographic information, but we hope this review can provide further elucidation into confounding risk factors and preventative measures for global nephrolithiasis analysis.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Stones in pregnancy and pediatrics

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

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.

Oral Zinc Sulfate as Adjuvant Treatment in Children With Nephrolithiasis: a Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND

Nephrolithiasis in children is associated with a high rate of complications and recurrence.

OBJECTIVES

Since some evidences reported that zinc has an important place amongst inhibitors of crystallization and crystal growth, we decided to assess the effectiveness of oral zinc sulfate as adjuvant treatment in children with nephrolithiasis.

PATIENTS AND METHODS

This was a randomized, double-blind, placebo-controlled clinical trial. 102 children in the age range 1 month to 11 years with first nephrolithiasis were recruited. Patients were randomly divided into two equal groups (intervention and control groups). Intervention group received conservative measures for stones and 1 mg/kg/day (maximum 20 mg/day) oral zinc sulfate syrup for 3 months. Control group received placebo in addition to conservative measures, also for 3 months. Patients were followed up by ultrasonography for 9 months, in 5 steps (at the end of 1st, 2nd, 3rd, 6th and 9th month after treatment) assessing size and number of stones in the kidneys.

RESULTS

Only at the end of the first month, the average number (intervention: 1.15 ± 3.78, control: 1.3 ± 2.84) (P = 0.001) and size (cm) (intervention: 0.51 ± 1.76, control: 0.62 ± 1.39) (P = 0.001) of stones was significantly lower in the intervention group, and in other points there was no significant therapeutic efficacy in oral zinc adjuvant treatment compared to conservative treatment alone. Also, during the 9-month follow-up, the number and size of stones in both groups decreased significantly (both: P < 0.0001) in a way that the decrease in the intervention group showed no difference with the control group.

CONCLUSIONS

Adjuvant treatment with zinc is not more effective than consecutive treatment in children with nephrolithiasis. However, further studies are recommended due to the lack of clinical evidence in this field.

Management of stone disease in infants

Evaluating and treating renal stone disease in infants are technically challenging. In this study, we evaluated the surgical treatment of renal stones in children under 1 year of age. We retrospectively reviewed the records of patients under 1 year old who were treated with ESWL, endourological or open surgical procedures for renal stone disease between January, 2009 and December, 2012. The patients' age, gender, stone size, stone location and number, complications, stone-free status, and postoperative complications were recorded. 19 of 121 infants with a mean age of 10.2 ± 3.07 months were treated with surgical procedures. Six (75%) of eight cystinuria patients required a surgical intervention. Retrograde endoscopic management was performed in thirteen patients (63.4%) as an initial surgical approach. There were three major (15.7%) complications. The rate of open surgical procedures was 31.6% (6 of 19 infants). The cutoff value of stone size for open surgery was 10 mm. There was a significant relationship between the conversion to open procedures and stone size, stone location, and symptom presentation especially the presence of obstruction (p < 0.05). After repeated treatments, the stone clearance rate of RIRS reached 84.6%. Retrograde intrarenal surgery is an effective and safe treatment method for renal stones in infants and can be used as a first-line therapy in most patients under 1 year old. This is especially important if an associated ureteral stone or lower pole stone that requires treatment is present and for patients with cystinuria, which does not respond favorably to ESWL.

Does obesity or hyperuricemia influence lithogenic risk profile in children with urolithiasis?

BACKGROUND

There are indications that obesity and hyperuricemia may influence the formation and composition of urinary stones. The aim of our study was to determine the effect of obesity and hyperuricemia on the urinary lithogenic risk profile in a large cohort of pediatric patients.

METHODS

The study population comprised 478 children with urolithiasis and 517 healthy children (reference group). We studied the effects of obesity on the lithogenic profile by dividing the patients with urolithiasis into two groups based on body mass index Z-score (patients who were overweight/obese vs. those with normal weight for age) and comparing the two groups. To study the effect of hyperuricemia on the lithogenic profile, we divided the patients with urolithiasis into two groups based on the presence or not of hyperuricemia (110 patients with urolithiasis accompanied by hyperuricemia vs. 368 patients with urolithiasis and normal serum uric acid levels) and compared the groups.

RESULTS

Among the children and adolescents with urolithiasis and hyperuricemia, there was a significantly lower excretion of crystallization inhibitors (citrates, magnesium). We also found significantly negative correlations between serum uric acid levels and the urine citrate/creatinine ratio (citrate/cr.; r = -0.30, p < 0.01), as well as the magnesium/cr. ratio (Mg/cr.; r = -0.33, p < 0.01). There was no statistically significant differences in the urinary excretion of oxalates, citrates, calcium, phosphorus, magnesium and uric acid between children with urolithiasis who were either overweight or obese and children with urolithiasis who had a normal body weight.

CONCLUSIONS

In our pediatric patient cohort, hyperuricemia was associated with a decrease in the excretion of crystallization inhibitors in the urine, but the clinical relevance of this observation needs to be confirmed in future studies. Obesity and overweight had no direct influence on the lithogenic risk profile in the urinary stone formers in our study, but there was an indication that higher serum uric acid may be associated with impairment in renal function, which in turn could influence the excretion of lithogenic parameters.

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

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

[Clinical and biochemical characterization of childhood urolithiasis]

OBJECTIVES

Urolithiasis is rare in children, but the incidence has increased over the past few decades. This study aims at describing the clinical and biochemical characteristics, etiology, and treatment of urolithiasis in children.

METHODS

This was a retrospective study of all children under 16 years of age seen at the Bordeaux University Children's Hospital with a diagnosis of urolithiasis. The diagnosis was confirmed either radiologically or clinically by the expulsion of the stone.

RESULTS

A total of 186 children with a diagnosis of urolithiasis between 1994 and 2012 were included. The median age at diagnosis was 7.4 years. The male-to-female ratio was 1.9. The estimated annual incidence was around 5.5/100,000 children under 15 years of age in the past 5 years. The main presenting feature was nonspecific abdominal pain (71%). Metabolic calculi accounted for 48% of the patients with idiopathic hypercalciuria as the main cause. Genetic diseases accounted for 15% of cases. The proportion of infectious calculi was estimated at 33% and decreased in the past two decades. Stone fragments were sent for analysis in 86 children, and calcium oxalate was the major component (37%), followed by calcium phosphate (33%), purine (9%), and struvite (8%). At least 26% of patients experienced recurrence of stone passage.

CONCLUSION

This retrospective study highlighted changes in characteristics of pediatric urolithiasis over time. Childhood-onset urolithiasis requires complete etiological work-up so that a metabolic cause with a high risk of recurrence does not go unrecognized.

Pediatric urolithiasis in a non-endemic country: a single center experience from The Netherlands

OBJECTIVE

To provide insight in causative factors of pediatric urolithiasis in The Netherlands, a non-endemic country.

PATIENTS AND METHODS

Data from 71 children with urolithiasis and stone analyses between 1996 and 2010 in the Radboud University Nijmegen Medical Centre were studied retrospectively. Patients (48 boys, 23 girls, ratio 2.1:1) were aged 0.5-18.3 years (mean 8.8, SD 5.6). All stone analyses were performed with FTIR spectroscopy.

RESULTS

Of the 49 patients with metabolic analysis, 78% showed one (n = 15) or more (n = 23) metabolic abnormalities. Forty-seven percent had hypercalciuria (n = 23), 31% had hyperoxaluria (n = 15), 29% hypocitraturia (n = 14), 10% hyperuricosuria (n = 5), 10% cystinuria (n = 5), and 6% had hypomagnesiuria (n = 3). Sixty-one percent of the stones were composed of calcium phosphate, calcium oxalate, or a combination of those. Twenty-six percent consisted of pure or mixed magnesium ammonium phosphate, 8.3% pure or mixed urate, and 8.3% cystine.

CONCLUSION

Children with urolithiasis in The Netherlands show stone composition similar to other Western European countries. However, a high percentage of metabolic abnormalities (78%) was found, indicating the need for extensive evaluation of pediatric urolithiasis to find underlying causes and thereby prevent stone recurrences. A close collaboration between a pediatric nephrologist and urologist is mandatory for optimal surgical and medical treatment.

Clinical importance of renal calyceal microlithiasis in children

BACKGROUND

Renal calyceal microlithiasis refers to a hyperechogenic spot in renal calyces <3 mm in diameter detected on renal sonography. These spots possibly represent the first step in calculus formation. The aim of this study was to analyze the clinical presentation, predisposing factors, prognosis and clinical importance of these hyperechogenic spots in renal calyces, renal calyceal microlithiasis, during childhood.

METHODS

The data of 292 children (135 girls, 157 boys) with microlithiasis diagnosed between January 1998 and December 2010 were evaluated retrospectively. Demographic data, serum biochemistry, urinary metabolic factors, and renal sonography results were obtained from patient files. A total of 228 patients were re-evaluated at least 6 months after the first observation of renal calyceal microlithiasis and at 6-12 month intervals thereafter.

RESULTS

Mean age was 16.8 ± 14.9 months, and mean follow-up duration was 14.6 ± 5.9 months. Presenting symptoms were abdominal or flank pain (41.1%), hematuria (35.6%), dysuria (24.7%) and urinary tract infection (34.6%). Previous ultrasounds were normal in 35% of the children. Metabolic and anatomic abnormalities were found in 55.5% and 17.8%, respectively. Hypercalciuria was the most common metabolic abnormality (88.9%). Among 228 patients who had been re-evaluated, microlithiasis disappeared in 37.7%; decreased in number or size in 23.7%; progressed to renal stone formation in 10.6%; increased in number of microlithiasis in 19.0%; and remained unchanged on radiology in 9.0%.

CONCLUSION

Renal calyceal microlithiasis represents a spectrum of clinical situations and underlying metabolic abnormalities that need further investigation in children.

[Urolithiasis in childhood]

Urinary stone disease is relatively rare in children with an overall incidence of 1-2 %; however, it is often associated with metabolic abnormalities that may lead to recurrent stone formation. Stone analysis and subsequent metabolic evaluation is therefore mandatory for this high-risk group after the first stone event. The objectives of stone management in children should be complete stone clearance, prevention of stone recurrence, preservation of renal function, control of urinary tract infections, correction of anatomical abnormalities and correction of the underlying metabolic disorders. The full range of minimally invasive procedures is available if active stone removal is necessary. The majority of stones in children can be managed either with extracorporeal shock wave lithotripsy which has a higher efficacy in children than in adults, percutaneous nephrolithotomy, ureterorenoscopy or a combination of these modalities while open or laparoscopic surgery is limited to well-selected cases with underlying anatomical abnormalities.

Assessment of risk factors of pediatric urolithiasis in Egypt

OBJECTIVE

Pediatric urolithiasis is a significant medical problem, which has seen an increasing incidence in developing countries. The main objective of the present study was to investigate the clinical characteristics and the most important risk factors that contribute to stone formation in Egyptian children.

PATIENTS AND METHODS

This prospective study was carried out at the outpatient clinics of Cairo university children's hospital as well as October 6 University hospitals, between November 2008 and March 2012. One hundred and fifty children (100 males, 50 females; mean age 3.5 years; range, 1-14 years) suffering from urinary stones were included. The mean follow-up duration; 33.1 months. All patients underwent detailed medical and family histories, dietary habits and physical examination, including Growth percentiles. Laboratory investigations were performed including: complete urine analysis and culture and sensitivity tests, urine collection in 24-h to quantity urinary volume, pH, calcium, uric acid, magnesium, creatinine, oxalate and citrate. Blood samples were obtained to measure (serum creatinine, calcium, phosphorus, uric acid level, and alkaline phosphatase and electrolyte levels, in addition to pH and pCO2 values). Radio-sonographic investigation of the abdomen and pelvis was also performed.

RESULTS

The commonest presentations were abdominal pain in 42 children (28%) and gross hematuria in 35 patients (23%). Urinary tract infection was the most common risk factor, 60 patients (40%) had UTI, 70% of them had recurrent infections. Genito-urinary abnormalities, as a risk factor, were detected in 38 children (25%), with vesico-uretheral refux being the commonest abnormality (18/38). Metabolic risk factors were detected in 34 children (23%) with hypercalciuria and hyperoxaluria being the commonest metabolic abnormalities. Treatments used were, ESWL in 69 patients (46%), endoscopic interventions in 40 children (27%) and open surgery in 15 children (10%). The remaining 26 children (17%) were managed conservatively.

CONCLUSIONS

treatment of pediatric urolithiasis requires stone removal besides a thorough metabolic and environmental evaluation of all patients on an individual basis, entailing the treatment of metabolic abnormalities. Children with a positive family history should be followed up cautiously to avoid stone recurrence.

Temporal trends in incidence of kidney stones among children: a 25-year population based study

PURPOSE

We conducted a population based pediatric study to determine the incidence of symptomatic kidney stones during a 25-year period and to identify factors related to variation in stone incidence during this period.

MATERIALS AND METHODS

The Rochester Epidemiology Project was used to identify all patients younger than 18 years who were diagnosed with kidney stones in Olmsted County, Minnesota from 1984 to 2008. Medical records were reviewed to validate first time symptomatic stone formers with identification of age appropriate symptoms plus stone confirmation by imaging or passage. The incidence of symptomatic stones by age, gender and study period was compared. Clinical characteristics of incident stone formers were described.

RESULTS

A total of 207 children received a diagnostic code for kidney stones, of whom 84 (41%) were validated as incident stone formers. The incidence rate increased 4% per calendar year (p = 0.01) throughout the 25-year period. This finding was due to a 6% yearly increased incidence in children 12 to 17 years old (p = 0.02 for age × calendar year interaction) with an increase from 13 per 100,000 person-years between 1984 and 1990 to 36 per 100,000 person-years between 2003 and 2008. Computerized tomography identified the stone in 6% of adolescent stone formers (1 of 18) from 1984 to 1996 vs 76% (34 of 45) from 1997 to 2008. The incidence of spontaneous stone passage in adolescents did not increase significantly between these 2 periods (16 vs 18 per 100,000 person-years, p = 0.30).

CONCLUSIONS

The incidence of kidney stones increased dramatically among adolescents in the general population during a 25-year period. The exact cause of this finding remains to be determined.

Percutaneous nephrolithotomy in children in different age groups: data from the Clinical Research Office of the Endourological Society (CROES) Percutaneous Nephrolithotomy Global Study

OBJECTIVES

To present the overall results of paediatric percutaneous nephrolithotomy (PCNL) compared with adults. To present the indications, complications and outcomes of patients treated in the participating centres in the PCNL Global Study, as categorised in different age groups.

PATIENTS AND METHODS

The Clinical Research Office of the Endourological Society (CROES) Study was conducted from November 2007 to December 2009, and included 96 centres and >5800 patients. All children aged ≤14 years in the PCNL Global Study database were the focus of the study.

RESULTS

In all, 107 children aged ≤14 years were included in the analysis. The PCNL procedure was conducted in 13 patients (12.1%) in the supine position; tubeless PCNL was performed in 15 patients (14%); and balloon dilatation was preferred in 22 patients (20.5%). The overall mean operative duration was 97.02 min; blood transfusion rate, fever and stone-free rates were 9%, 14% and 70.1%, respectively. A comparison of the paediatric PCNL cases according to age groups showed no statistically significant differences between the subgroups for patient characteristics, co-morbidities, renal anomalies, or previous surgical history. In the evaluation of the operative details, the mean sheath size and nephrostomy tube size were larger in school-age children than the preschool children (P = 0.01 and 0.002, respectively). There was a difference in the preferred methods for confirming stone-free status, with ultrasonography preferred more in preschool children (P < 0.001). The PCNL procedure position, puncture site, dilatation method, postoperative tube application, and surgical outcomes were comparable in school- and preschool-age children. While operative details showed some differences between children and adults, the surgical outcomes were comparable.

CONCLUSIONS

A considerable number (45.7%) of the paediatric patients had a previous history of stone intervention. Based on the findings of the present study, we can suggest that PCNL can be applied safely and effectively in children in different age groups. Outcomes appear comparable with those in adults for the success and complication rates, in the presence of substantial indications, appropriate equipment and adequate experience.

Pediatric urolithiasis: causative factors, diagnosis and medical management

Childhood urolithiasis is associated with considerable morbidity and recurrence. Many risk factors--including those metabolic, genetic, anatomic, dietary and environmental in nature--have been identified in children with urinary tract calculi. As pediatric urolithiasis with a metabolic etiology is the most common disease, evaluating the metabolic risk factors in patients is necessary to both effectively treat current stones and prevent recurrence. We discuss causative risk factors of pediatric urolithiasis, as well as the diagnostic and therapeutic approaches.

Urolithiasis in infants: evaluation of risk factors

OBJECTIVE

Urolithiasis in infants is not a very rare situation in Turkey, and the incidence has been increasing in recent years. The purpose of this paper was to investigate the clinical characteristics, metabolic and anatomic risk factors for urolithiasis and microlithiasis in infants.

METHODS

The cases of 178 infants (63 girls, 115 boys), who were referred to our department between 1999 and 2009 with urolithiasis, were evaluated.

RESULTS

The mean age at diagnosis of stone disease was 11.5 months (range, 10 days-24 months). The mean follow-up duration was 33.6 months (1.2-110 months). The major clinical symptoms of our patients were restlessness in 24 children (13.5%) and vomiting in 23 (13%). Thirty-five infants (19.7%) had a urinary tract abnormality; vesico-ureteral reflux was the most common abnormality (12.9%). Hypercalciuria and hyperuricosuria were detected in 46 and 56%, respectively. Stone analysis was performed in 56 infants, and calcium oxalate was determined in 36 patients (64.3%). A family history of urolithiasis, presenting symptoms and underlying metabolic abnormalities were similar for patients with microlithiasis and those with larger stones. However, infants with microlithiasis had higher ratios for history of vitamin D administration and feeding with formula. Surgical treatment was performed in 42 infants and extracorporeal shock wave lithotripsy in 30 infants.

CONCLUSION

Our results showed that urolithiasis in infants may present nonspecific symptoms and may even be asymptomatic and that a positive family history for urolithiasis, urologic abnormalities, metabolic disorders, urinary tract infections, vitamin D administration and feeding with formula may increase the occurrence of urolithiasis in infants.

Body fat composition and occurrence of kidney stones in hypercalciuric children

In the last 10 years, the incidence of kidney stones has increased in the pediatric population, and this rise has been paralleled by a significant increase in pediatric obesity rates in the USA. The purpose of this study was to evaluate percentage body fat (%BF) measured by dual energy X-ray absorptiometry (DXA) in hypercalciuric children with and without kidney stones. A retrospective chart review was performed on children with idiopathic hypercalciuria based on a 24-h urine calcium excretion of >4 mg/kg/day or >200 mg/day who had undergone DXA scanning. Patients were then classified by sex and by %BF (3 categories; normal: <27% girls, <21% boys; at risk for obesity: 27-36% girls, 21-30% boys; obese: >36% girls, >30% boys). The 2003-2004 NHANES data were used as a control. Fifty patients (24 males) were analyzed, of whom 26% were assessed as having a normal %BF, 44% as being at risk for obesity, and 30% as being obese. Children with an increased %BF had a significantly higher occurrence of kidney stones (p = 0.03) than those with a normal %BF. No significant differences were noted in 24-h urine chemistries between the groups. In conclusion, an increased %BF was associated with an increased occurrence of kidney stones in children with idiopathic hypercalciuria.

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

Nephrolithiasis in children is a painful and costly disease that may also have detrimental long-term effects on kidney function. Recent data provide evidence that the incidence of nephrolithiasis in children is rising. Children who are white, female, and adolescent seem to have the highest risk for forming symptomatic kidney stones. Although the reasons for the rising incidence and demographic discrepancies in pediatric nephrolithiasis are not yet clear, recent investigations into urine chemistry provide clues regarding predisposing metabolic risk factors. As more data emerge regarding epidemiologic and metabolic characteristics of pediatric kidney stone formers, we hope to gain a better understanding of the causes of kidney stone disease and, ultimately, provide better strategies for stone prevention in children.

Metabolic and demographic characteristics of children with urolithiasis in Western Turkey

Pediatric urolithiasis is an endemic disease in Turkey. We evaluated the clinical, radiological and metabolic features of children with urolithiasis in Western Turkey. We retrospectively reviewed the records of 85 children with urolithiasis who were followed-up between 2004 and 2010 in Pediatric Nephrology Department of Celal Bayar University, Manisa. The male/female ratio was 1.23/1. The mean age at diagnosis was 66.1 months (range 3-210 months). Family history of urolithiasis was found in 58 (68.2%) patients. 23 (27%) patients were born from consanguineous marriages. Stones were located in the upper urinary tract in 79 (92.9%) patients. In 66 (77.6%) patients, stones were single-sided and 41 (48.2%) patients had multiple stones. Calcium oxalate stones were the most common one among patients in whom stone analysis was performed (78.5%). Hypocitraturia was the most commonly detected urinary metabolic risk factor. In patients who were under 12 months of age at diagnosis, hypercalciuria was the most commonly seen urinary metabolic risk factor. At the end of follow-up period, 24 patients became free of stone disease and 4 patients had recurrence. In conclusion, metabolic abnormalities are common in pediatric stone patients and are strongly associated with recurrence. Considering that urolithiasis in children is an important risk factor for renal failure, early diagnosis, detailed metabolic evaluation and implementing appropriate treatment and follow-up protocols may prevent recurrence and renal damage.

Diagnostic examination of the child with urolithiasis or nephrocalcinosis

Urolithiasis and nephrocalcinosis are more frequent in children then currently anticipated, but still remain under- or misdiagnosed in a significant proportion of patients, since symptoms and signs may be subtle or misleading. All children with colicky abdominal pain or macroscopic hematuria should be examined thoroughly for urolithiasis. Also, other, more general, abdominal manifestations can be the first symptoms of renal stones. The patients and their family histories, as well as physical examination, are important initial steps for diagnostic evaluation. Thereafter, diagnostic imaging should be aimed at the location of calculi but also at identification of urinary tract anomalies or acute obstruction due to stone disease. This can often be accomplished by ultrasound examination alone, but sometimes radiological methods such as plain abdominal films or more sensitive non-enhanced computed tomography are necessary. Since metabolic causes are frequent in children, diagnostic evaluation should be meticulous so that metabolic disorders that cause recurrent urolithiasis or even renal failure, such as the primary hyperoxalurias and others, can be ruled out. The stone is not the disease itself; it is only one serious sign! Therefore, thorough and early diagnostic examination is mandatory for every infant and child with the first stone event, or with nephrocalcinosis.

Familiality of kidney stone disease in Iceland

OBJECTIVE

The aetiology of kidney stones is multifactorial, with environmental and genetic factors contributing to the pathogenesis. The aim of this study was to assess the role of genetic factors in kidney stone disease by examining the heritability of the trait in Icelandic patients.

MATERIAL AND METHODS

Medical records at all major hospitals and imaging centres in Iceland were searched for diagnostic codes indicative of kidney stones, yielding a cohort of 5954 incident patients with kidney stone disease. The list of patients was cross-matched with a genealogy database that covers the entire Icelandic nation. The risk ratio (RR) and kinship coefficient (KC) were calculated to determine the risk of kidney stones in relatives of stone formers and the relatedness among kidney stone patients.

RESULTS

The risk of kidney stones among family members of stone formers was significantly higher than in the general population. In 2959 patients with radiopaque stones, the RR ranged from 2.25 (p<0.001) for first degree relatives of probands (such as parents or siblings) to 1.07 (p<0.01) in fifth degree relatives. Moreover, for confirmed recurrent stone formers the RR of kidney stones in parents and offspring was in excess of 10 (p<0.001). The KC analysis shows that Icelandic patients with kidney stone disease are significantly more related to each other than is the average Icelander, even when considering only relatives separated by four meioses or more (p<0.05).

CONCLUSIONS

The results suggest that genetic factors may substantially influence the risk of kidney stone disease in Iceland.

Urolithiasis in the first year of life

Data on urolithiasis (UL) in infancy are limited. The objective of this study was to increase awareness of infant UL and to investigate the influence of possible risk factors in this very specific age group. Nonfasting, second-voiding urine samples were obtained to test for urinary excretions of calcium, oxalate, citrate, magnesium, uric acid, and creatinine. Blood analysis included calcium, phosphate, magnesium, uric acid, creatinine, sodium, potassium, chloride, and alkaline phosphatase. Patients received follow-up testing every 1-2 months; serial ultrasonography was used to track UL status. Fifty infants with a median age of 5 months were enrolled in the study. Hypercalciuria was detected in 9/47, hyperoxaluria in 5/39, hypocitraturia in 4/31, and cystinuria in 2/50 infants. We identified at least one metabolic abnormality in 46% of our patients; no metabolic abnormality was identified in 27 infants. Within a mean follow-up period of 14 months, 17 infants became stone free, stones increased in number in ten patients and decreased in number in 16, and recurrence was detected in seven. This study showed that UL could be detected in very early life, even in the newborn period, and could be the source of late childhood/adulthood UL. Infants with nonspecific symptoms such as restlessness may have UL and should undergo ultrasonographic examination. Metabolic evaluation of UL in this specific age group carries some diagnostic challenges, e.g. unsatisfactory data regarding normal ranges of urinary mineral excretion, and collection of 24-h urine samples.

History, epidemiology and regional diversities of urolithiasis

Archeological findings give profound evidence that humans have suffered from kidney and bladder stones for centuries. Bladder stones were more prevalent during older ages, but kidney stones became more prevalent during the past 100 years, at least in the more developed countries. Also, treatment options and conservative measures, as well as 'surgical' interventions have also been known for a long time. Our current preventive measures are definitively comparable to those of our predecessors. Stone removal, first lithotomy for bladder stones, followed by transurethral methods, was definitively painful and had severe side effects. Then, as now, the incidence of urolithiasis in a given population was dependent on the geographic area, racial distribution, socio-economic status and dietary habits. Changes in the latter factors during the past decades have affected the incidence and also the site and chemical composition of calculi, with calcium oxalate stones being now the most prevalent. Major differences in frequency of other constituents, particularly uric acid and struvite, reflect eating habits and infection risk factors specific to certain populations. Extensive epidemiological observations have emphasized the importance of nutritional factors in the pathogenesis of urolithiasis, and specific dietary advice is, nowadays, often the most appropriate for prevention and treatment of urolithiasis.

Recurrent abdominal pain in childhood urolithiasis

OBJECTIVE

Our goal was to establish the clinical presentation and features of pain attacks in children with recurrent abdominal pain (RAP) and urolithiasis.

METHODS

We compared the rate of previous appendectomy among 100 consecutive patients with that of 270 control subjects. We also compared the frequency of pain attacks with that reported by children with functional or organic gastrointestinal RAP.

RESULTS

Fifty-three patients had no history of dysuria or gross hematuria, and only 35 had hematuria at the first visit; 41 patients were evaluated for urolithiasis only because of a family history of kidney stones associated with RAP. Twenty-nine patients had been previously hospitalized for abdominal symptoms. Sixteen patients and 4 control subjects (1.5%) had undergone a previous appendectomy (P < .0001). Two to 28 months before the diagnosis of urolithiasis, 37 patients underwent abdominal ultrasonography, which did not show urinary stones. Sixty-nine percent of subjects younger than 8 years of age had central/diffuse abdominal pain. The mean frequency of pain attacks was 4 to 9 times lower than in patients with functional or organic gastrointestinal RAP.

CONCLUSIONS

Because of the inconstant occurrence of dysuria and hematuria, the location of pain in areas other than the flank, and the lack of calculi shown on imaging studies performed after pain attacks, the urologic origin of pain may be overlooked and ineffective procedures performed. The possibility of urolithiasis should be considered in children with RAP who have a family history of urolithiasis and/or infrequent pain attacks, even when dysuria and hematuria are lacking, and in younger children even when pain is not lateral.

Spontaneous urinary calcium oxalate crystallization in hypercalciuric children

Idiopathic hypercalciuria is the most important predisposing risk factor for calcium oxalate (CaOx) renal stone formation. We assessed the associations between spontaneous CaOx crystallization based on the Bonn Risk Index (BRI), urinary pH, calciuria, oxaluria, and citraturia in 140 Caucasian patients with hypercalciuria, aged 4-17 years, and compared the findings with those in 210 normocalciuric controls. Of the 140 hypercalciuric patients, 58 had renal stones, and 82 had recurrent erythrocyturia, renal colic, or urinary obstructive symptoms-but without stones. Urinary ionized calcium ([Ca(2+)]) levels were measured using a selective electrode, while the onset of crystallization was determined using a photometer and titration with 40 mmol/L ammonium oxalate (Ox(2-)). The calculation of the BRI was based on the [Ca(2+)]:Ox(2-) ratio. The BRI values were 12-fold higher in hypercalciuric children than in healthy controls, but no differences were found in the BRI between subjects with urinary stones and those with urolithiasis-like symptoms. An increased BRI suggested an association with hypercalciuria, lower urinary pH, hypocitraturia, and hypooxaluria. These data indicate that hypercalciuria is an important factor associated with increased urinary CaOx crystallization, although the causal pathways need further investigation. Determination of the BRI in children with hypercalciuria may improve the risk assessment of kidney stones.

Clinical and metabolic risk factor evaluation in young adults with kidney stones

INTRODUCTION

The most frequent urine metabolic risk factor in adults is idiopathic hypercalciuria while in children is hypocitraturia. If there is really a change of metabolic abnormalities with age it would be interesting to study risk factors in the intermediate population: young adults.

OBJECTIVE

We evaluated metabolic risk factors, clinical presentation and family history of stone formers between 17 and 27 years old.

METHODS

A total of 160 patients (87 males and 73 females) were studied with a standard protocol.

RESULTS

A single urine metabolic risk factor was present in 64% of the patients, and multiple risk factors were present in 27% of them. No metabolic abnormalities were found in the remaining 9%. The most common urine risk factor was idiopathic hypercalciuria (alone or in combination), which was identified in 42.5% followed by hypocitraturia (alone or in combination) found in 32.9% of the patients. In the subgroup of patients of 17-20 years (n = 75; mean age of 18.8 + or - 1.0 years), hypocitraturia (alone or in combination) was as frequent as idiopathic hypercalciuria (alone or in combination), which was identified in 38% (n = 30) and 36.7% (n = 29), respectively. The most frequent form of presentation was renal colic (72%). A positive family history of stone disease in first degree and second-degree relatives was found in 32.9 and 34.1%, respectively.

CONCLUSIONS

Metabolic abnormalities were found in 91% of young adults with renal lithiasis, similar to our adult series. Hypercalciuria was the most frequent metabolic abnormality found. Yet, hypocitraturia (alone or in combination) was very frequent, and in the subgroup of patients of 17-20 years, it was as frequent as idiopathic hypercalciuria, similar to what we found in children.

Sequence variants in the CLDN14 gene associate with kidney stones and bone mineral density

Kidney stone disease is a common condition. To search for sequence variants conferring risk of kidney stones, we conducted a genome-wide association study in 3,773 cases and 42,510 controls from Iceland and The Netherlands. We discovered common, synonymous variants in the CLDN14 gene that associate with kidney stones (OR = 1.25 and P = 4.0 x 10(-12) for rs219780[C]). Approximately 62% of the general population is homozygous for rs219780[C] and is estimated to have 1.64 times greater risk of developing the disease compared to noncarriers. The CLDN14 gene is expressed in the kidney and regulates paracellular permeability at epithelial tight junctions. The same variants were also found to associate with reduced bone mineral density at the hip (P = 0.00039) and spine (P = 0.0077).

Metabolic risk factors in children with kidney stone disease

The evaluation of metabolic risk factor in children with renal stone disease is the basis of medical treatment aimed at preventing recurrent stone events and the growth of preexisting calculi. In this retrospective study, we evaluated the metabolic risk factors and clinical and family histories of 90 children with kidney stone disease who had been referred to our institution and subjected to clinical tests using a standardized protocol. The mean age of our pediatric patients was 10.7 years, and the male:female ratio was 1.14:1.0. Biochemical abnormalities were found in 84.4% of all cases. A single urine metabolic risk factor was present in 52.2% (n = 47) of the patients, and multiple risk factors were present in the remaining 31.1% (n = 28). Idiopathic hypercalciuria (alone or in combination) and hypocitraturia (alone or in combination) were the most frequent risk factors identified in 40 and 37.8% of these patients, respectively. Renal colic or unspecified abdominal pain were the most frequent forms of presentation (76.9%), with 97.5% of stones located in the upper urinary tract. In most patients, stone disease was confirmed by renal ultrasonography (77%). A positive family history in first-degree and second-degree relatives was found in 46.2 and 32.5% of the cases, respectively. We conclude that specific urine metabolic risk factors are found in most children with kidney stones and that hypocitraturia is as frequent as hypercalciuria. Very often there is a positive family history of renal stone disease in first- and second-degree relatives.

Pediatric urolithiasis: an 8-year experience of single centre

OBJECTIVE

The objective was to investigate the clinical features and metabolic and anatomic risk factors for kidney stone formation in our patient group.

METHODS

Between 1998 and 2005, 179 children (94 girls, 85 boys) followed in our department because of urolithiasis were enrolled to participate in our study. Clinical presentation, urinary tract infection, stone localisation, positive family history, stone composition, presence of anatomic abnormalities and urinary metabolic risk factors, and treatment modality were evaluated retrospectively.

RESULTS

The mean age at diagnosis of stone disease was 4.5 years (range 0.25-15.3 years). The mean follow-up duration was 8 months (range 1-98). The major clinical presentations of our patients were abdominal pain and/or flank pain in 100 children (55.9%) and macroscopic hematuria in 25 (14%). Urinary tract infection was detected in 20% of patients on admission. Forty-three children (24%) had a urinary tract abnormality and ureteropelvic junction obstruction was the most common abnormality. A family history of stone disease was recorded in 98 patients (54.7%). Stones were located within the renal parenchyma in 90 patients. Hypercalciuria and hyperuricosuria were detected in 42.3 and 54.8% respectively. Stone analysis was performed in 63 children and calcium oxalate was a major mineral. Surgical treatment was performed in 49 children and extracorporeal shock wave lithotripsy (ESWL) in 41 children.

CONCLUSION

We think that urolithiasis remains a serious problem in children in our country. Family history of urolithiasis, urologic abnormalities (especially under the age of 5 years), metabolic disorders and urinary tract infections tend to indicate childhood urolithiasis.

Genotype and haplotype determination of IL1B (g. −511C>T and g. +3954C>T) and (IL1RN) in pediatric nephrolithiasis

BACKGROUND

Nephrolithiasis is a multifactorial and polygenic disorder characterized by presence of stones in urinary tract. Interleukin1 (IL1) plays role in process of bone loss/hypercalciuria and is involved in formation of kidney stones. We investigated the association between IL1B promoter region and exon-5 (g.-511C>T and g. +3954C>T) polymorphism and variable number of tandem repeats in IL1 receptor antagonist, IL1RN (IVS2) with risk of stone formation in childhood nephrolithiasis in north Indian population.

METHODS

Control group of 60 healthy pediatric individuals (age range =4-16 y) and 50 pediatric nephrolithiasis patients (age range =2-14 y) were studied. Polymorphism was detected by PCR based restriction analysis. Haplotypes for IL1B and IL1RN were constructed using Arlequin v2.0 software.

RESULTS

Distribution of IL1RN gene polymorphism demonstrated significant difference (p=0.023). Pediatric patients had significantly higher frequency of allele I in IL1RN (16% vs. 1.7%). The distribution of IL1B (g. -511C>T and g. +3954C>T) genotypes in patients and controls were similar (p=0.263 and 0.694 respectively). There was a significant difference in haplotype frequencies between pediatric patients and control group (p<0.05). Haplotype T-E1-I showed>7-folds risk for nephrolithiasis (p=0.033; OR=7.07, 95% CI=1.16-42.84).

CONCLUSIONS

Significant association was observed for allele I(*) of IL1RN however, no association was observed for IL1B. Haplotype T-E1-I was significantly associated with higher risk of pediatric nephrolithiasis. These findings suggest that the IL1RN and haplotyping may be an influential marker for susceptibility to pediatric nephrolithiasis.

Pathophysiology of hypercalciuria in children

Urinary excretion of calcium is the result of a complex interplay between three organs-namely, the gastrointestinal tract, bone, and kidney-which is finely orchestrated by multiple hormones. Hypercalciuria is believed to be a polygenic trait and is influenced significantly by diet. This paper briefly reviews calcium handling by the renal tubule in normal and in hereditary disorders as it relates to the pathophysiology of hypercalciuria. The effects of dietary sodium, potassium, protein, calcium, and phosphate on calcium excretion, and the association of hypercalciuria with bone homeostasis is discussed, leading to recommendations on means to address excessive urinary calcium excretion.