Diagnostic examination of the child with urolithiasis or nephrocalcinosis

International Alliance of Urolithiasis (IAU) guidelines on the management of pediatric urolithiasis

The aim of this study was to construct the sixth in a series of guidelines on the treatment of urolithiasis by the International Alliance of Urolithiasis (IAU) that by providing a clinical framework for the management of pediatric patients with urolithiasis based on the best available published literature. All recommendations were summarized following a systematic review and assessment of literature in the PubMed database from January 1952 to December 2023. Each generated recommendation was graded using a modified GRADE methodology. Recommendations are agreed upon by Panel Members following review and discussion of the evidence. Guideline recommendations were developed that addressed the following topics: etiology, risk factors, clinical presentation and symptoms, diagnosis, conservative management, surgical interventions, prevention, and follow-up. Similarities in the treatment of primary stone episodes between children and adults, incorporating conservative management and advancements in technology for less invasive stone removal, are evident. Additionally, preventive strategies aiming to reduce recurrence rates, such as ensuring sufficient fluid intake, establishing well-planned dietary adjustments, and selective use pharmacologic therapies will also result in highly successful outcomes in pediatric stone patients. Depending on the severity of metabolic disorders and also anatomical abnormalities, a careful and close follow-up program should inevitably be planned in each pediatric patient to limit the risk of future recurrence rates.

Risk factors for recurrence in pediatric urinary stone disease

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Comprehensive evaluation of patients with primary hyperoxaluria type 1: A nationwide study

BACKGROUND

Primary hyperoxaluria type 1 (PH1) is characterized by increased endogenous oxalate production and deposition as calcium oxalate crystals. The main manifestations are nephrocalcinosis/nephrolithiasis, causing impaired kidney function. We aimed to evaluate the clinical characteristics and overall outcomes of paediatric PH1 patients in Turkey.

METHODS

This is a nationwide, multicentre, retrospective study evaluating all available paediatric PH1 patients from 15 different paediatric nephrology centres in Turkey. Detailed patient data was collected which included demographic, clinical and laboratory features. Patients were classified according to their age and characteristics at presentation: patients presenting in the first year of life with nephrocalcinosis/nephrolithiasis (infantile oxalosis, Group 1), cases with recurrent nephrolithiasis diagnosed during childhood (childhood-onset PH1, Group 2), and asymptomatic children diagnosed with family screening (Group 3).

RESULTS

Forty-eight patients had a mutation consistent with PH1. The most common mutation was c.971_972delTG (25%). Infantile oxalosis patients had more advanced chronic kidney disease (CKD) or kidney failure necessitating dialysis (76.9% vs. 45.5%). These patients had much worse clinical course and mortality rates seemed to be higher (23.1% vs. 13.6%). Patients with fatal outcomes were the ones with significant comorbidities, especially with cardiovascular involvement. Patients in Group 3 were followed with better outcomes, with no kidney failure or mortality.

CONCLUSION

PH1 is not an isolated kidney disease but a systemic disease. Family screening helps to preserve kidney function and prevent systemic complications. Despite all efforts made with traditional treatment methods including transplantation, our results show devastating outcomes or mortality.

Fifteen-minute consultation: An approach to the child with nephrocalcinosis

Nephrocalcinosis is a common problem faced in both paediatrics and neonates, which may need referral on to paediatric nephrology. This 15 min consultation aims to look at children of different age groups (neonates, children 1-5 years old and older children) looking particularly at history, examination, causes, initial investigations and management.

The Saudi urological association guidelines on urolithiasis

Aims

The Saudi Urolithiasis Guidelines are a set of recommendations for diagnosing, evaluating, and treating urolithiasis in the Saudi population. These guidelines are based on the latest evidence and expert consensus to improve patient outcomes and optimize care delivery. They cover the various aspects of urolithiasis, including risk factors, diagnosis, medical and surgical treatments, and prevention strategies. By following these guidelines, health-care professionals can improve care quality for individuals with urolithiasis in Saudi Arabia.

Panel

The Saudi Urolithiasis Guidelines Panel consists of urologists specialized in endourology with expertise in urolithiasis and consultation with a guideline methodologist. All panelists involved in this document have submitted statements disclosing any potential conflicts of interest.

Methods

The Saudi Guidelines on Urolithiasis were developed by relying primarily on established international guidelines to adopt or adapt the most appropriate guidance for the Saudi context. When necessary, the panel modified the phrasing of recommendations from different sources to ensure consistency within the document. To address areas less well covered in existing guidelines, the panel conducted a directed literature search for high quality evidence published in English, including meta analyses, randomized controlled trials, and prospective nonrandomized comparative studies. The panel also searched for locally relevant studies containing information unique to the Saudi Arabian population. The recommendations are formulated with a direction and strength of recommendation based on GRADE terminology and interpretation while relying on existing summaries of evidence from the existing guidelines.

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

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

Pediatric renal lithiasis in Spain: research, diagnostic and therapeutic challenges, and perspectives

Incidence and prevalence of urolithiasis is apparently increasing worldwide, also among children and adolescents. Nevertheless, robust data have only been obtained in a few countries. In Spain, a voluntary Registry for Pediatric Renal Lithiasis has been active since 2015. Irregular participation limits its applicability, as well as its limitation to patients with a stone available for morphocompositional study, to obtain data about incidence and prevalence. On the other hand, findings about typology of stones and clinical and analytical characteristics of these subjects have been communicated in several meetings. Other valuable efforts in this field are the elaboration of guidelines for the collection and processing of urine samples for the study of urolithiasis in pediatric patients with the consensus of the Spanish Society for Pediatric Nephrology (AENP) as well as the Spanish Society for Laboratory Medicine (SEQC), the collaborative network RenalTube for the diagnosis of primary tubulopathies and the registry of patients with Primary Hyperoxaluria (OxalSpain). In many hospitals from the public healthcare system, pediatric nephrologists are the specialists in charge of the management of children with kidney stones, but there is no formal regulation on this competence. Other specialists, such as urologists, pediatric surgeons or pediatric urologists, in many cases do not offer a complete insight into the etiopathogenic mechanisms and the consequent medical treatment. Access to medication according to standards of treatment is warranted, provided a correct diagnosis is achieved, but criteria for the reimbursement of certain therapies, such as RNAi drugs for primary hyperoxaluria, are arguable.

How to solve a clinical conundrum: Have you tried a trio exome analysis?

The following report describes the clinical journey of a 5-month-old male infant who presented with a significant kidney injury following a diarrhoeal illness. His course was complicated by severe hypertension and a number of acute life-threatening events necessitating periods of time on the intensive care unit, where he received ventilatory support and underwent renal replacement therapy and treatment with a monoclonal antibody therapy.We take the reader on a stepwise journey from presentation through to final diagnosis, discussing important biochemical, haematological and radiological features where learning points are discussed. Guidance on the use of genomic testing strategies for the non-geneticist is provided in some detail with a particular focus on the trio exome analysis that identified the diagnosis for this young boy.This complex case not only provides a number of excellent learning opportunities but also highlights the importance of early involvement of the clinical genetics team and the relevance of the trio exome analysis for rapid identification of rare monogenic diseases.

Etiology and prognosis of nephrocalcinosis according to gestational age in Korean children

BACKGROUND

Nephrocalcinosis (NC) is defined as deposition of calcium in renal tubules and interstitium and is highly related with prematurity and monogenic diseases. Recent studies have reported that NC might be a specific finding of underlying hereditary renal diseases. This study evaluated the risk factors, underlying monogenic causes, and clinical outcomes of NC in Korean children according to gestational age (GA).

METHODS

A total of 464 patients younger than 18 years who were diagnosed with NC by ultrasonography from January 2013 to December 2022 in Samsung Medical Center were enrolled. Medical record data of sex, GA, birth weight, underlying disease, medication history, ultrasonography and genetic analysis were reviewed retrospectively.

RESULTS

The male to female ratio was 1:0.98, and the mean age at first diagnosis of NC was 385 days. Approximately 62% of patients experienced confirmed resolution of NC after about one year. In comparison of the preterm (mean GA 28 weeks and 2 days) and full-term (mean GA 38 weeks and 2 days) groups, bronchopulmonary dysplasia, patent ductus arteriosus, and use of furosemide and vitamin D were more frequent in the preterm group. In the full-term group, a larger proportion of cases showed persistent NC without resolution and chronic kidney disease (CKD). Genetic analyses were performed in 56 patients, and the monogenic mutation rate was significantly higher in full-term children (OR 10.02, 95% CI [2.464-40.786], p = 0.001).

CONCLUSION

While the overall outcomes of pediatric NC are favorable, underlying monogenic causes should be studied, especially in full-term patients without known clinical risk factors.

Hypercalcemia in an Infant with Primary Hyperoxaluria Type 2: A Novel Association

Hypercalcemia in infants presents with a variety of clinical features and the etiology of hypercalcemia varies with age. Here we present a case of hypercalcemia in an infant presenting with nephrocalcinosis and nephrolithiasis. Our investigations led us to a diagnosis of primary hyperoxaluria (PH) type 2, a rare metabolic disorder, along with hypercalcemia, a never before reported association. A 9-month-old female presented with urinary tract infection and systemic features requiring hospitalization and parenteral antibiotics. Investigations revealed bilateral medullary nephrocalcinosis. Genetic testing revealed a diagnosis of Primary hyperoxaluria type 2 with two possible mutations. Sanger sequencing of the parents identified the pathogenic mutation in the mother. This is the first report of a genetically proven case of primary hyperoxaluria type 2 associated with hypercalcemia.

Urinary stone disease in Syrian children

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Is cerebral palsy associated with successful ureteral access during the initial attempt at ureteroscopy for urolithiasis in children and young adults?

BACKGROUND

Ureteroscopy is a common treatment for urolithiasis, but initial ureteral access is not always possible, particularly in pediatrics. Clinical experience suggests that neuromuscular conditions such as cerebral palsy (CP) may facilitate access, thus avoiding the need for pre-stenting and staged procedures.

OBJECTIVE

We sought to determine if probability of successful ureteral access (SUA) during initial attempted ureteroscopy (IAU) is higher in pediatric patients with CP vs. without CP.

STUDY DESIGN

We reviewed IAU cases for urolithiasis (2010-2021) at our center. Patients with pre-stenting, prior ureteroscopy, or urologic surgical history were excluded. CP was defined using ICD-10 codes. SUA was defined as scope access to urinary tract level sufficient to reach stone. Association of CP and other factors with SUA were evaluated.

RESULTS

230 patients (45.7% male, median age: 16 years [IQR: 12-18 y], 8.7% had CP) underwent IAU, with SUA in 183 (79.6%). SUA occurred in 90.0% of patients with CP vs. 78.6% of those without CP (p = 0.38). SUA was 81.7% in patients >12 years (vs. 73.8% in those <12), and the highest SUA was in those >12 years with CP (93.3%), but these differences were not statistically significant. Renal stone location was significantly associated with lower SUA (p = 0.007). Among patients with renal stone only, SUA in those with CP was 85.7% vs. 68.9% in those without CP (p = 0.33). SUA did not differ significantly by gender or BMI.

CONCLUSIONS

CP may facilitate ureteral access during IAU in pediatric patients, but we were unable to show a statistically significant difference. Further study of larger cohorts may demonstrate whether CP or other patient factors are associated with successful initial access. Improved understanding of such factors would help preoperative counseling and surgical planning for children with urolithiasis.

Secondary Prevention of Diabetes Type 1 with Oral Calcitriol and Analogs, the PRECAL Study

Screening for Type 1 Diabetes (T1D, incidence 1:300) with T1D autoantibodies (T1Ab) at ages 2 and 6, while sensitive, lacks a preventive strategy. Cholecalciferol 2000 IU daily since birth reduced T1D by 80% at 1 year. T1D-associated T1Ab negativized within 0.6 years with oral calcitriol in 12 children. To further investigate secondary prevention of T1D with calcitriol and its less calcemic analog, paricalcitol, we initiated a prospective interventional non-randomized clinical trial, the PRECAL study (ISRCTN17354692). In total, 50 high-risk children were included: 44 were positive for T1Ab, and 6 had predisposing for T1D HLA genotypes. Nine T1Ab+ patients had variable impaired glucose tolerance (IGT), four had pre-T1D (3 T1Ab+, 1 HLA+), nine had T1Ab+ new-onset T1D not requiring insulin at diagnosis. T1Ab, thyroid/anti-transglutaminase Abs, glucose/calcium metabolism were determined prior and q3-6 months on calcitriol, 0.05 mcg/Kg/day, or paricalcitol 1-4 mcg × 1-3 times/day p.o. while on cholecalciferol repletion. Available data on 42 (7 dropouts, 1 follow-up < 3 months) patients included: all 26 without pre-T1D/T1D followed for 3.06 (0.5-10) years negativized T1Ab (15 +IAA, 3 IA2, 4 ICA, 2 +GAD, 1 +IAA/+GAD, 1 +ICA/+GAD) within 0.57 (0.32-1.3) years or did not develop to T1D (5 +HLA, follow-up 3 (1-4) years). From four pre-T1D cases, one negativized T1Ab (follow-up 1 year), one +HLA did not progress to T1D (follow-up 3.3 years) and two +T1Ab patients developed T1D in 6 months/3 years. Three out of nine T1D cases progressed immediately to overt disease, six underwent complete remission for 1 year (1 month-2 years). Five +T1Ab patients relapsed and negativized again after resuming therapy. Four (aged <3 years) negativized anti-TPO/TG, and two anti-transglutaminase-IgA. Eight presented mild hypercalciuria/hypercalcemia, resolving with dose titration/discontinuation. Secondary prevention of T1D with calcitriol and paricalcitol seems possible and reasonably safe, if started soon enough after seroconversion.

Calculus anuria: a urological emergency with an excellent outcome

Calculus anuria is a catastrophic condition with dire consequences if not treated promptly. The purpose of this study was to identify factors which influence the short-term outcome of patients with calculus anuria. A retrospective analysis was conducted from January 2016 to December 2021, in children up to the age of 18 years, who presented with calculus anuria and required emergency decompression at Sindh Institute of Urology and Transplantation, Pakistan. One hundred and twenty-five children were included. Majority were born to consanguineous parents and a few of them had positive family history of stone disease. Severe illness was found in 25 (20%) patients and among them 8 (32%) required hemodialysis. Decompression by double J stenting is the preferred intervention in our institute and was done in 106 (85%) children, followed by percutaneous nephrostomy tube in 10 (8%) successfully. A small number of patients, 9 (7%) required both procedures to relieve their obstruction. A significant number of patients, about 115 (92%), attained normal renal functions after intervention. No pertinent factors were identified, relating to incomplete renal recovery in nine (7%) of the patients who unfortunately progressed to chronic kidney disease.

Risk factors for developing hyperoxaluria in children with Crohn's disease

BACKGROUND

For the purpose of a better understanding of enteric hyperoxaluria in Crohn's disease (CD) in children and adolescents, we investigated the occurrence and risk factors for development of hyperoxaluria in those patients.

METHODS

Forty-five children with CD and another 45 controls were involved in this cross-sectional study. Urine samples were collected for measurement of spot urine calcium/creatinine (Ur Ca/Cr), oxalate/creatinine (Ur Ox/Cr), and citrate/creatinine (Ur Citr/Cr) ratios. Fecal samples were also collected to detect the oxalyl-CoA decarboxylase of Oxalobacter formigenes by PCR. Patients were classified into 2 groups: group A (with hyperoxaluria) and group B (with normal urine oxalate excretion). The disease extent was assessed, and the activity index was calculated.

RESULTS

According to the activity index, 30 patients (66.7%) had mild disease and 13 patients (28.9%) had moderate disease. There was no significant difference in Ur Ox/Cr ratio regarding the disease activity index. O. formigenes was not detected in 91% of patients in group A while it was detected in all patients in group B (p < 0.001). By using logistic regression analysis, the overall model was statistically significant when compared to the null model, (χ2 (7) = 52.19, p < 0.001), steatorrhea (p = 0.004), frequent stools (p = 0.009), and O. formigenes (p < 0.001).

CONCLUSION

Lack of intestinal colonization with O. formigenes, steatorrhea, and frequent stools are the main risk factors for development of enteric hyperoxaluria in CD patients. Identifying risk factors facilitates proper disease management in future studies. A higher resolution version of the Graphical abstract is available as Supplementary information.

Pediatric Nephrolithiasis

The prevalence of pediatric nephrolithiasis has increased dramatically in the past two decades for reasons that have yet to be fully elucidated. Workup of pediatric kidney stones should include metabolic assessment to identify and address any risk factors predisposing patients to recurrent stone formation, and treatment should aim to facilitate stone clearance while minimizing complications, radiation and anesthetic exposure, and other risks. Treatment methods include observation and supportive therapy, medical expulsive therapy, and surgical intervention, with choice of treatment method determined by clinicians' assessments of stone size, location, anatomic factors, comorbidities, other risk factors, and preferences and goals of patients and their families. Much of the current research into nephrolithiasis is restricted to adult populations, and more data are needed to better understand many aspects of the epidemiology and treatment of pediatric kidney stones.

Proteomic analysis of inhibitory protein profiles in the urine of children with nephrolithiasis: implication for disease prevention

PURPOSE

In this study we aimed to screen for the presence of biomarkers that are downregulated in children with nephrolithiasis (RS) compared to healthy controls (HC) using a proteomic approach. We hypothesized that RS and HC would display unique inhibitory protein profiles that could be used for comparative pathway analysis.

METHODS

This is a prospective, controlled, pilot study of pooled urine from RS (N = 30, 24 females, mean age 12.95 ± 4.03 years) versus age- and gender-matched HC, using liquid chromatography-mass spectrometry. The criteria for protein selection were: (1) patient/control abundance ratio of < 0.5; and (2) ≤ 0.05 p-value for the Fisher's Exact Test. Results were confirmed by ELISA testing in individual samples.

RESULTS

67 proteins were downregulated in RS group, and 17 of those were significantly different compared to controls. Of those seventeen proteins, five (two actins, annexin A5, keratin 6B, and serpin B4) were completely absent in the urine of stone patients but were found in controls. The remaining twelve proteins were significantly less abundant in the patient's urine compared to healthy controls. Protein-protein interaction modeling of significant proteins identified syndecan-1 as the key node, a protein associated with adhesion pathways. ELISA analysis by subgroups showed statistically significant difference in the urinary excretion of osteopontin (5.1 ± 3.22 ng/mg creatinine vs 14.1 ± 9.5 ng/mg creatinine, p = 0.046) between stone patients with hypocitraturia and controls. Urinary osteopontin concentration was positively correlated with urinary citrate excretion (r = 0.417, p = 0.03).

CONCLUSIONS

Children with RS have a different urinary inhibitory polypeptide profile compared to HC. Decreased urinary excretion of these proteins indicates their potential inhibitory role in renal stone formation, especially of the adhesion phase. Lower concentration of urinary osteopontin in children with nephrolithiasis and hypocitraturia suggests its potential involvement in the pathogenesis of this disease. Further characterization of these proteins in a larger sample is imperative.

Switching from conventional therapy to burosumab injection has the potential to prevent nephrocalcinosis in patients with X-linked hypophosphatemic rickets

OBJECTIVES

X-linked hypophosphatemic rickets (XLH) is a congenital fibroblast growth factor (FGF)23-related metabolic bone disease that is treated with active vitamin D and phosphate as conventional therapies. Complications of these therapies include nephrocalcinosis (NC) caused by excessive urine calcium and phosphate concentrations. Recently, an anti-FGF23 antibody, burosumab, was developed and reported to be effective in poorly-controlled or severe XLH patients. This study aimed to reveal the impact of switching treatments in relatively well-controlled XLH children with the Rickets Severity Scale less than 2.0.

METHODS

The effects of the two treatments in eight relatively well-controlled XLH children with a mean age of 10.4 ± 1.9 years were compared retrospectively for the same treatment duration (31 ± 11 months) before and after the baseline.

RESULTS

Actual doses of alfacalcidol and phosphate as conventional therapy were 150.9 ± 43.9 ng/kg and 27.5 ± 6.3 mg/kg per day, respectively. Renal echography revealed spotty NC in 8/8 patients, but no aggravation of NC was detected by switching treatments. Switching treatments increased TmP/GFR (p=0.002) and %TRP (p<0.001), and improved the high urine calcium/creatinine ratio to the normal range (p<0.001) although both treatments controlled disease markers equally. Additionally, low intact parathyroid hormone during conventional therapy was increased within the normal range by switching treatments.

CONCLUSIONS

Our results suggest that a high dose of alfacalcidol was needed to control the disease, but it caused hypercalciuria and NC. We concluded that switching treatments in relatively well-controlled XLH children improved renal phosphate reabsorption and decreased urine calcium extraction, and may have the potential to prevent NC.

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.

Novel mutations in TRPM6 gene associated with primary hypomagnesemia with secondary hypocalcemia. Case report

BACKGROUND

Primary hypomagnesemia with secondary hypocalcemia (HSH) is a rare genetic disorder. Dysfunctional transient receptor potential melastatin 6 causes impaired intestinal absorption of magnesium, leading to low serum levels accompanied by hypocalcemia. Typical signs at initial manifestation are generalized seizures, tetany, and/or muscle spasms.

CASE REPORT

We present a 5 w/o female manifesting tonic-clonic seizures. Laboratory tests detected severe hypomagnesemia and hypocalcemia. The molecular genetic analysis revealed two novel mutations within the TRPM6 gene c.3308dupC (p.Pro1104Thrfs*28) (p.P1104Tfs*28) and c.3958C>T (p.Gln1302*) (p.Q1302*) and the patient was successfully treated with Mg supplementation.

CONCLUSION

Ion disbalance should be taken into account in the differential diagnosis of infantile seizures. Accurate diagnosis of HSH together with appropriate treatment are crucial to prevent irreversible neurological outcomes.

Pediatric stone disease: Current management and future concepts

Treatment of pediatric urolithiasis consists of medical and surgical approaches. The main goal of the treatment is to prevent stone recurrence by avoiding multiple surgical interventions. In recent years, many innovations have been reported in the medical diagnostic evaluation protocol and in surgical treatment. According to recent reports, single mutations could be responsible for a larger proportion of renal stones. This etiologic feature holds the potential to change the management in stone prevention from metabolically directed therapy to more specific approaches. In addition, miniaturized instruments have been adopted in clinical practice. In recent years, minimally invasive endoscopic surgery is the treatment of choice in pediatric urolithiasis. This review aims to assess the current literature on medical and surgical treatment options for pediatric urolithiasis. We also aim to provide an overview of potential future advances.

[Nephrocalcinosis in children]

Nephrocalcinosis is defined by calcium phosphate or calcium oxalate deposits in the kidney parenchyma, particularly in tubular epithelial cells and interstitial tissue. It should be differentiated from urolithiasis where calcium salts deposits are located in the kidney and urinary tract. The epidemiology of nephrocalcinosis in children is unknown but the condition is not so rare, with an increased incidence in preterm infants. Often detected as an incidental finding, nephrocalcinosis may be classified according to the radiological type: medullary, cortical or diffuse. Nephrocalcinosis in children can be caused by a variety of etiology. The most common causes concern medullary nephrocalcinosis and include hereditary tubular disorders, in particular distal renal tubular acidosis and Dent disease, metabolic disorders such as idiopathic hypercalciuria and hyperoxaluria, and iatrogenic causes such as vitamin D intoxication. In the newborn, the main cause is hypercalciuria of the premature baby, whose multifactorial origin is largely iatrogenic. Primary hyperoxaluria which can lead to early onset nephrocalcinosis and usually to chronic kidney disease should always be considered and further investigated. In order to provide a specific diagnosis, it is essential to take into account the family history, the clinical context and complete laboratory data. Early initiation of an appropriate etiological treatment is recommended and may prevent or delay the progression to chronic kidney disease in some cases.

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

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

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.

Hypophosphataemic Rickets: Diagnosis Algorithm-How Not to Make a Mistake

Hypophosphataemic rickets is a heterogeneous group of entities characterized by rickets or osteomalacia due to a phosphate deficit caused mainly by decreased renal reabsorption. They are also characterized by defective intestinal absorption of calcium and rickets or osteomalacia unresponsive to cholecalciferol. These metabolic alterations lead to growth retardation, bone pain and deformities, and short stature. For a correct diagnosis and treatment of all forms of rickets, the basic aspects of pathophysiology of the calcium-phosphorus metabolism and the relevance of the bone-kidney axis modulated by the presence of phosphaturic agents need to be known. Diagnosis of these diseases includes clinical assessment, blood and urine analytical tests, and bone x-ray. The aim of this article is to briefly describe the pathophysiology, signs, symptoms, and clinical forms of hypophosphataemic rickets, proposing a diagnosis algorithm that can help in the clinical practice.

Inherited conditions resulting in nephrolithiasis

PURPOSE OF REVIEW

Prevalence of pediatric urolithiasis is increasing, which is definitively visible in increasing numbers of presentations in emergency or outpatient clinics. In pediatric patients, a genetic or metabolic disease has to be excluded, so that adequate treatment can be installed as early as possible. Only then either recurrent stone events and chronic or even end-stage kidney disease can be prevented.

RECENT FINDINGS

The genetic background of mostly monogenic kidney stone diseases was unravelled recently. In hypercalcuria, for example, the commonly used definition of idiopathic hypercalciuria was adopted to the genetic background, here three autosomal recessive hereditary forms of CYP24A1, SLC34A1 and SLC34A3 associated nephrocalcinosis/urolithiasis with elevated 1.25-dihydroxy-vitamin D3 (1.25-dihydroxy-vitamin D3) (calcitriol) levels. In addition either activating or inactivating mutations of the calcium-sensing receptor gene lead either to hypocalcemic hypercalciuria or hypercalcemic hypocalciuria. In primary hyperoxaluria, a third gene defect was unravelled explaining most of the so far unclassified patients. In addition, these findings lead to new treatment options, which are currently evaluated in phase III studies.

SUMMARY

Kidney stones are not the disease itself, but only its first symptom. The underlying disease has to be diagnosed in every pediatric patient with the first stone event.

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Ultrasonography in Detection of Renal Calculi in Children; a Systematic Review and Meta-analysis

INTRODUCTION

Although numerous studies have been done to evaluate the diagnostic value of ultrasonography in diagnosis of renal calculi in children, there is still no consensus. Therefore, in the present systematic review and meta-analysis, we aimed to evaluate the diagnostic accuracy of ultrasonography in identifying renal stones in children.

METHODS

A comprehensive search of the electronic databases including Medline, Embase, Scopus and Web of Science was conducted up to July 2019. Diagnostic accuracy studies in children were included. Data was summarized and pooled. Area under the curve (AUC), sensitivity, specificity, diagnostic score and diagnostic odds ratio were reported with 95% confidence interval (95% CI).

RESULTS

Data from 7 articles were included. Pooled analysis showed that the area under the curve of ultrasonography in diagnosis of pediatric renal calculi was 0.94 (95% CI: 0.92 to 0.96). The sensitivity and specificity of this diagnostic modality were 0.80 (95% CI: 0.70 to 0.87) and 1.00 (95% CI: 0.84 to 1.00), respectively. Diagnostic score and diagnostic odds ratio of ultrasonography in detection of renal calculi were 110.32 (95% CI: 2.88 to 19.76) and 82362.41 (95% CI: 17.80 to 3.8 × 10⁸), respectively.

CONCLUSION

Overall, the low level of evidence indicates that sensitivity and specificity of ultrasonography in detecting renal calculi in children are 80% and 100%, respectively. However, due to the serious limitations of the included studies, well-designed prospective diagnostic accuracy studies are recommended for future studies.

Individualized treatment with denosumab in children with osteogenesis imperfecta - follow up of a trial cohort

Background

Osteogenesis imperfecta (OI) is a rare disease leading to hereditary bone fragility. Nearly 90% of cases are caused by mutations in the collagen genes COL1A1/A2 (classical OI) leading to multiple fractures, scoliosis, short stature and nonskeletal findings as blue sclera, hypermobility of joints, bone pain and delayed motor function development. Bisphosphonates are used in most moderate and severely affected patients assuming that an increase of bone mineral density might reduce fractures and bone pain in patients with OI. Denosumab as a RANK ligand antibody inhibiting osteoclast maturation has been approved for osteoporosis treatment in adults. First data from small clinical trials promised a high efficacy of Denosumab in children with OI. Aim of this analysis was a retrospective evaluation of an individualized biomarker-associated treatment regime with Denosumab in 10 children with classical OI which were followed for 1 year after their participation in a pilot trial with Denosumab. Therefore urinary deoxypyridinoline levels were evaluated frequently as an osteoclastic activity marker and depending on that levels Denosumab injections were scheduled individually.

Methods

Ten patients (age range: 6.16–12.13 years; all participated in the former OI-AK phase 2 trial (NCT01799798)) were included in the follow-up period. Denosumab was administered subcutaneously depending on the individual urinary excretion course of deoxypyridinoline (DPD/Crea) as osteoclastic activity marker with 1 mg/kg body weight. DPD/Crea levels were evaluated before denosumab administration and afterwards. If patients present after an initial decrease after injection with a re-increase up to the DPD/crea level before Denosumab injection next dosage was planned. Changes of areal bone mineral density (aBMD) using dual energy x-ray absorptiometry of the lumbar spine after 12 month was evaluated. Safety was assessed by bone metabolism markers and side effect reporting.

Results

During follow-up mean relative change of lumbar aBMD was − 6.4%. Lumbar spine aBMD z-Scores decreased from − 1.01 ± 2.61 (mean ± SD) to − 1.91 ± 2.12 (p = 0.015). Mobility changed not significantly (GMFM-88 -6.49 ± 8.85% (p = 0.08). No severe side effects occurred. Dose intervals could be extended in the mean from 12 weeks previously to 20.3 weeks.

Conclusions

On average, it was possible to prolong the intervals between drug administrations and to reduce the total dose about by 25% without a decrease of mobility or change of vertebral shape despite a reduction of lumbar aBMD during 1 year of biomarker-directed Denosumab treatment. Further trials are necessary to balance side effects and highest efficacy in children.

Metabolic Disorders in Iranian Children with Urolithiasis

Background:Children with urolithiasis have a wide range of metabolic disorders which should be carefully considered. The response to medical treatment could predict recurrence and need for surgical interventions. Objectives:The goal of this retrospective study is to determine the prevalence of metabolic disorders in Iranian children and assess patients' response to treatment based on the etiology of their urolithiasis. Materials and methods:Medical record of 100 children with urolithiasis who were referred to Bahrami hospital (affiliated hospital of Tehran University of Medical Sciences) between 2007 and 2017. Data regarding age, sex, family history, symptoms, size of the stones, type of treatments, response to treatment, and recurrence were recorded for all cases Results:Subjects had a mean age of 36 ±36 months and 62 (62%) of them were females. Twenty-two percent had a family history of urolithiasis. The mean age was 37.2±35 months in the complete response group, 38±44.4 months in the partial group, and 30±33.1 months in the no response group (p=0.7). There was no significant difference regarding sex and age with treatment response (p=0.8). In the complete response group, nearly 72% of cases had stones with sizes less than 3 mm. Three cases had surgical interventions and 18 had recurrence. Conclusions:Hypercalciuria followed by hyperoxaluria were the most common metabolic disorders in Iranian children with urolithiasis. Stone size plays an important role in the response to treatment.

Nephrocalcinosis and Nephrolithiasis in X-Linked Hypophosphatemic Rickets: Diagnostic Imaging and Risk Factors

Context

Nephrocalcinosis (NC) and nephrolithiasis (NL) are described in hypophosphatemic rickets, but data regarding their prevalence rates and the presence of metabolic risk factors in X-linked hypophosphatemic rickets (XLH) are scarce.

Objective

To determine the prevalence rates of NC and NL and their risk factors in patients with XLH with confirmed PHEX mutations.

Methods

Renal ultrasonography (US) and CT were performed in 16 children and 23 adults. The images were evaluated by two blinded radiologists specializing in US and two specializing in CT. Confirmation of NC was determined with a positive result on both US and CT, whereas the diagnosis of NL was confirmed by CT alone. The presence of hypercalciuria, hypocitraturia, and hyperoxaluria was determined from 24-hour urinary samples from each patient. The glomerular filtration rate was estimated.

Results

NC was identified in 15 patients (38.4%), and stratification by age group showed a higher prevalence of NC in children than in adults (56.2% vs 26.1%). CT identified NL in four adults (10.2%). Patients in the pediatric group required intensive use of phosphate, started treatment earlier, and presented greater phosphaturia than those in the adult group (P < 0.01). In addition to hyperphosphaturia, which was present in all patients with XLH, hypocitraturia was the most common metabolic factor (28.2%), whereas hypercalciuria occurred in two patients (5.1%). None had hyperoxaluria. Most patients had normal renal function.

Conclusions

NC was more prevalent than NL. The main metabolic factor was hyperphosphaturia, and intensive phosphate treatment appears to be a worsening factor for kidney calcification.

Multidimensional Analysis of Urinary Stone Diseases in Pediatric Patients

Objectives:

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

Methods:

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

Results:

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

Conclusion:

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

Pediatric urolithiasis in Morocco: Composition of 432 urinary calculi analyzed by infrared spectroscopy

PURPOSE

Incidence of pediatric urolithiasis is decreasing in most developing countries where endemic bladder stones are less prevalent than in the past years. In parallel, stone composition has changed. Only few data are available in North Africa, except for Tunisia. We report stone composition in the Moroccan pediatric population.

MATERIAL AND METHODS

Composition of 432 stones from children (302 boys, 130 girls) was determined by infrared spectroscopy. The samples were collected during the period 1999-2016. Stone morphology, which is an important aspect for etiology was determined by examination of each stone under a stereomicroscope. Stone composition was compared to patients' age and gender.

RESULTS

The global male-to-female ratio was 2.32. Regarding stone composition, calcium oxalate was the main component in 51.6% of the stones, followed by struvite (18.1%), ammonium urate (9.5%) and carbapatite (9%). Significant differences were found between males and females: calcium oxalate accounted for 72.3% of stones in girls and 42.7% in boys (P<10^-6); conversely, struvite was more frequent in boys than in girls (22.2 vs 8.5%, P<10^-4). The same was found for calcium phosphate stones (11.9% in boys; 4.6% in girls, P<0.05). Stone morphology helped us for detecting several pathological conditions: type Ic whewellite stones, as a marker for primary hyperoxaluria, was found in 17.6% of stones and type IIId ammonium urate stones, suggestive for infectious diarrhea, was identified in 20.1% of all stones.

CONCLUSION

This is the largest series of pediatric stones in Morocco studied by infrared analysis and morphological examination.

LEVEL OF EVIDENCE

3.

Genetische Nierensteinerkrankungen

Die Inzidenz und Prävalenz von Steinerkrankungen haben in den letzten Jahren deutlich zugenommen. Es ist von entscheidender Bedeutung, möglichst frühzeitig eine richtige Diagnose der zugrunde liegenden Erkrankung zu stellen, um die richtige Therapie einzuleiten und damit möglicherweise schwerwiegende Folgen, wie terminales Nierenversagen, zu verhindern. Bei Kindern lassen sich in ca. 75 % der Fälle genetische oder anatomische Ursachen identifizieren. Die verschiedenen zugrunde liegenden Erkrankungen für die jeweiligen lithogenen Risikofaktoren werden hier präsentiert und die entsprechenden Therapieoptionen, sofern vorhanden, erläutert.

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.

Urinary proteomics reveals association between pediatric nephrolithiasis and cardiovascular disease

PURPOSE

To study (1) the differences in the relative abundance of urinary proteins between children with kidney stones (RS) and hypercalciuria, hypocitraturia, normal metabolic work-up, and healthy controls (HC); (2) the association of these proteins with various diseases.

METHODS

Quantitative proteomic comparison of pooled urine from RS (N = 30, 24 females, mean age 12.95 ± 4.03 years) versus age- and gender-matched HC, using mass spectrometry. Relative protein abundance was estimated using spectral counting. Proteins of interest were selected using the following criteria: (1) ≥ 5 spectral counts; (2) ≥ twofold difference in spectral counts; and (3) ≤ 0.05 p value for the Fisher's Exact Test.

RESULTS

Of the 1813 proteins identified, 229 met the above criteria, with 162 proteins up-regulated in the RS group and 67 up-regulated in HC. The largest group of proteins (30 out of 229) was found to be associated with cardiovascular disease (CVD). Of those, 16 were involved in coagulation, fibrinolysis, and adhesion, 10 in inflammation, 5 in lipid transport and metabolism, and 4 in oxidative stress. All except two were exclusively found in children with hypercalciuria and hypocitraturia, and were not seen in children with normal metabolic work-up.

CONCLUSION

Using a proteomic approach, we found a significant association between hypercalciuric and hypocitraturic nephrolithiasis and CVD in children. The shared risk factors among both diseases are endothelial dysfunction and atherosclerosis caused by abnormal coagulation, adhesion, disturbance of lipid transport and metabolism, oxidative stress and inflammation. Further understanding of the pathophysiological link between nephrolithiasis and CVD is necessary for developing new therapeutic targets.

Alström syndrome: Renal findings in correlation with obesity, insulin resistance, dyslipidemia and cardiomyopathy in 38 patients prospectively evaluated at the NIH clinical center

Alström Syndrome is a ciliopathy associated with obesity, insulin resistance/type 2 diabetes mellitus, cardiomyopathy, retinal degeneration, hearing loss, progressive liver and kidney disease, and normal cognitive function. ALMS1, the protein defective in this disorder, localizes to the cytoskeleton, microtubule organizing center, as well as the centrosomes and ciliary basal bodies and plays roles in formation and maintenance of cilia, cell cycle regulation, and endosomal trafficking. Kidney disease in this disorder has not been well characterized. We performed comprehensive multisystem evaluations on 38 patients. Kidney function decreased progressively; eGFR varied inversely with age (p = 0.002). Eighteen percent met the definition for chronic kidney disease (eGFR < 60 mL/min/1.73 m² and proteinuria); all were adults with median age of 32.8 (20.6-37.9) years. After adjusting for age, there were no significant associations of kidney dysfunction with type 2 diabetes mellitus, dyslipidemia, hypertension, cardiomyopathy or portal hypertension suggesting that kidney disease in AS is a primary manifestation of the syndrome due to lack of ALMS1 protein. Approximately one-third of patients had hyperechogenicity of the renal parenchyma on imaging. While strict control of type 2 diabetes mellitus may decrease kidney-related morbidity and mortality in Alström syndrome, identification of novel targeted therapies is needed.

Urinary stone risk factors in the descendants of patients with kidney stone disease

BACKGROUND

Evidence has indicated that immediate family members of nephrolithiasis patients had high opportunity to develop stones. However, they are usually not regarded to be at risk, since it is unclear if there are any lithogenic abnormalities found in non-stone-forming nephrolithiasis relatives. Our aim was to investigate urinary metabolic abnormalities in the children of nephrolithiasis patients, compared with the general population.

METHODS

The 24-h urinary metabolic profile was studied for 28 calcium oxalate nephrolithiasis patients (NL) and 46 of their descendants (ND), as well as 40 non-stone-forming volunteers (V) and 34 of their descendants (VD).

RESULTS

There was no difference between age, gender, and serum creatinine between NL vs. V (parental groups) and ND vs. VD (descendant groups). High urinary oxalate in nephrolithiasis and urinary calcium in their descendants was detected. In addition, an elevated urinary excretion rate of calcium, phosphate, protein, and albumin, along with low citrate excretion and high urinary supersaturation was observed in both the nephrolithiasis patients and their descendants. Approximate 17.8-24.4% of the nephrolithiasis descendants had a urinary supersaturation higher than the nephrolithiasis level, but none was found in VD group. The level of urinary supersaturation index was correlated with urinary protein and albumin excretion in nephrolithiasis family.

CONCLUSION

It was demonstrated that nephrolithiasis offspring carried several urinary metabolic risks predisposing to stone formation which are similar to their parents, and about one in every five nephrolithiasis children had nephrolithiasis level urinary supersaturation.