Pediatric kidney stones: Long-term outcomes

Etiology and management of urethral calculi: A systematic review of contemporary series

Objective

To conduct a systematic literature review on urethral calculi in a contemporary cohort describing etiology, investigation, and management patterns.

Methods

A systematic search of MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases was performed. Articles, including case reports and case series on urethral calculi published between January 2000 and December 2019, were included. Full-text manuscripts were reviewed for clinical parameters including symptomatology, etiology, medical history, investigations, treatment, and outcomes. Data were collated and analyzed with univariate methods.

Results

Seventy-four publications met inclusion criteria, reporting on 95 cases. Voiding symptoms (41.1%), pain (40.0%), and acute urinary retention (32.6%) were common presenting features. Urethral calculi were most often initially investigated using plain X-ray (63.2%), with almost all radio-opaque (98.3%). Urethral calculi were frequently associated with coexistent bladder or upper urinary tract calculi (16.8%) and underlying urethral pathology (53.7%) including diverticulum (33.7%) or stricture (13.7%). Urethral calculi were most commonly managed with external urethrolithotomy (31.6%), retrograde manipulation (22.1%), and endoscopic in situ lithotripsy (17.9%).

Conclusion

This unique systematic review of urethral calculi provided a summary of clinical features and treatment trends with a suggested treatment algorithm. Management in contemporary urological practice should be according to calculus size, shape, anatomical location, and presence of urethral pathology.

Calcium Carbonate Urolithiasis in a Pediatric Patient: A Case Report

Urinary stones composed of calcium carbonate are extremely rare, accounting for 0.01%-1.4% of urolithiasis (UL) cases. Urolithiasis is an infrequent condition in the pediatric population worldwide and in Mexico; nevertheless, the incidence in the Yucatán Peninsula is higher than that reported in other areas of Mexico and the world. Urolithiasis is the second most common urinary disease among pediatrics in the Yucatán Peninsula, which makes it an endemic region for this disease. We describe the case of a five-year-old male from the southeast region of Mexico who presented with signs and symptoms of urinary tract infection (UTI) and was diagnosed with bilateral staghorn stones of calcium carbonate, successfully treated by mini endoscopic combined intra-renal surgery, and dietary adjustments to prevent recurrence.

Is percutaneous nephrolithotomy effective and safe for children with solitary kidney?

PURPOSE

To evaluate the safety and efficacy of percutaneous nephrolithotomy (PCNL) in pediatric patients with solitary kidneys and kidney stones.

METHODS

Thirty-nine patients (group A) with solitary kidney under 18 years of age who underwent PCNL between January 2015 and December 2021 were evaluated and analyzed. Forty-two patients (group B) with bilateral kidneys who underwent PCNL were determined as the control group and included in the analysis. Intraoperative and postoperative data such as demographic data, stone localization, bleeding and transfusion rates, operation time, complications, hospital stay, stone-free rates (SFR) and kidney function (glomerular filtration rate (eGFR)) were compared between the two groups. PCNL was performed with all patients in the prone position. Only a laser was used to fragment the stone in all cases. Stone-free was defined as the absence of residual stone fragments ≥ 2 mm in maximum diameter at 3 months on kidney, ureter and bladder (KUB) graphy, ultrasonography (US) or non-contrast tomography (NCCT).

RESULTS

The mean ages of the patients in Group A and B were 7.5 ± 2.6 and 8.5 ± 3.1 years, respectively. The mean stone size was 16.5 ± 4.1 and 17.0 ± 3.2 mm in group A and group B, respectively (p = 0.49). SFR rates in Groups A and B were 97.4% and 95.2% (p = 1.00). There was no statistically significant difference in terms of the operation time, perioperative blood transfusion, hemoglobin decrease and Clavien grade 1 complication rates (p > 0.05). However, double-J (JJ) stent placement, duration of nephrostomy and hospital stay were longer in the solitary kidney group (p < 0.05). There was a significant improvement in creatinine and eGFR levels in both groups at the postoperative sixth month (p < 0.05).

CONCLUSION

Our results show that PCNL is a safe and effective method in pediatric patients with solitary kidneys.

Mini versus ultra-mini percutaneous nephrolithotomy in a paediatric population

OBJECTIVE

To evaluate whether there would be a difference in outcome when the smaller ultra-mini 12 Fr sheath was used instead of the mini 16 Fr sheath for percutaneous nephrolithotomy (PCNL) in paediatric patients for stones less than 25 mm.

METHODS

This was a prospective cohort study of patients who underwent PCNL in our hospital in a 2-year period from July 2016 to June 2018 by a single surgeon. PCNL was performed in a prone position and tract was dilated to the respective size using single step dilatation. Laser was used to fragment the stone. Stone-free outcome was defined as absence of stone fragment at 3 months on kidney, ureter, and bladder X-ray.

RESULTS

There were 40 patients in each group. Mean stone size was comparable between the two groups (14.5 mm vs. 15.0 mm). The procedure was completed faster in the 16 Fr group compared to 12 Fr group (24.5 min vs. 34.6 min). Stone clearance was highly successful in both groups (97.5% vs. 95.0%). There was no difference in complications between the two groups. The decrease in hemoglobin was minimal in both groups (0.2 g/dL vs. 0.3 g/dL).

CONCLUSION

We found that the success rates were similar in both mini PCNL and the smaller ultra-mini PCNL groups. No significant difference in bleeding was noted in our pilot study, however, operative time was longer in the ultra-mini group as compared to the mini sheath group.

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.

Distribution of APOE gene polymorphism in the Chinese Uyghur children & its association with urolithiasis

BACKGROUND & OBJECTIVES

This study was to survey the apolipoprotein E (APOE) gene polymorphism distribution among Chinese Uyghur children and to explore the relationship between APOE gene polymorphism and the occurrence of urolithiasis.

METHODS

A total of 144 Uyghur children with urolithiasis and 274 without the history of urolithiasis were enrolled in this study. Venous blood samples were collected from all participants, and APOE genotyping, derived from rs429358 and rs7412, was performed using Sanger sequencing.

RESULTS

Among the 418 children, the most prevalent genotype was E3/3, accounting for 71.3 per cent in the urolithiasis group and 71.4 per cent in the control group, followed by E3/4 and E2/3. Higher frequencies of the ɛ2 and ɛ4 alleles and lower frequencies of the ɛ3 allele were observed in the test group, and the unusual allele ɛ1 was also found in them. However, there were no significant differences between cases and controls at both rs429358 and rs7412 genotype and allele frequencies [odds ratio (OR)=0.98, 95% confidence interval (CI): 0.57-1.67; 0.98 (0.59-1.63); 1.43 (0.75-2.74) and 1.40 (0.74-2.62), respectively]. Likewise, none of significant differences was found between cases and controls at both APOE genotype and allele frequencies [OR=0.88, 95% CI: 0.51-1.53; 0.74 (0.33-1.64); 1.10 (0.73-1.66); 1.13 (0.76-1.67) and 1.14 (0.76-1.70), respectively].

INTERPRETATION & CONCLUSIONS

The present study does not support any association between APOE genotyping and urolithiasis in Uyghur children.

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.

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

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

Effectiveness and complications of mini-percutaneous nephrolithotomy in children: one center experience with 232 kidney units

OBJECTIVE

To evaluate the efficacy and complications of mini-percutaneous nephrolithotomy (PCNL) surgery using 14-20 Fr access sheaths in pediatric patients, as well as the results of postoperative stone analysis and metabolic urine analysis.

MATERIAL AND METHODS

We retrospectively evaluated the records of 206 pediatric patients (232 kidney units) who underwent mini-PCNL for kidney stones in our clinic between February 2011 and December 2018. We evaluated the demographic characteristics, complications, stone-free rates, and the results of chemical analysis and urinary metabolic analysis.

RESULTS

The age ranged from 9 months to 16 years. The mean age was 5.1±3.9 years, and the median age was 3.5 years. The median stone burden was 200 mm² (min: 100; max: 1600). Kidney stones were most commonly located in the pelvis in 118 (50.9%) patients, followed by lower calyceal stones in 42 (18.1%) and multiple calyceal stones in 38 (16.4%) patients, respectively. While the success of mini-PCNL was 80.6% after the first session, this rate increased to 87.9% after auxiliary treatments. The total complication rate was 12.9% according to modified Clavien classification. A postoperative stone analysis showed that calcium oxalate had the highest frequency with 61.1% of patients, followed by cystine stone with 21.3% of patients. Metabolic urine analysis revealed no abnormalities in 42.8% of patients. The most common metabolic abnormality was hyperoxaluria (32%), followed by hypercalcuria (19.6%).

CONCLUSION

Mini-PCNL is a safe and effective procedure with reasonable complications for the treatment of pediatric kidney stones. All kinds of multidisciplinary efforts are required to remove kidney stones completely in pediatric patients.

Combined Laparoscope and Flexible Ureteroscope Pyelolithotomy Dealing with Large-Burden Complex Renal Calculi in Children Less Than 1 Year Old

Objective: To evaluate the experience and result of combined laparoscope and flexible ureteroscope (f-URS) pyelolithotomy in dealing with large-burden complex renal calculi in children <1 year old. Methods: Eleven patients (7 males and 4 females) <1 year old were retrospectively reviewed between December 2015 and May 2017, who had been diagnosed with renal calculi and received combined laparoscope and f-URS pyelolithotomy. The operations were carried out under general anesthesia. Patient' characteristics, presenting symptoms, operative times, and blood loss, stone-free rate, and postoperative complications were all collected retrospectively. Results: All 11 patients received combined laparoscope and f-URS pyelolithotomy. All operations went smoothly without conversion record and blood transfusion. Average time consumed was 109 minutes (55-187 minutes), and blood loss reported was 16 mL (10-25 mL). Average hospital stay after operation was 7 days (5-11 days). On mean follow-up of 6-12 months, no symptomatic urinary tract infections and urinary calculi were detected. Conclusion: Laparoscope combined f-URS pyelolithotomy is considered safe in the treatment of large-burden multiple renal calculi in infant patients with a high stone clearance rate. It has certain advantages in the treatment of renal calculi in infants <1 year old, and it could be an alternative treatment when other treatments fail or are unavailable.

Rigid ureteroscopy in children: Our experience

Aim:

To report our experience of Pediatric ureterorenoscopy for ureteric calculi from two tertiary Pediatric urology centers at Apollo Children's Hospital, Chennai and Indraprastha Apollo Hospital, New Delhi.

Material and methods:

All children who presented with symptomatic ureteric stones greater than 6 mm were entered into the study. All children less than 12 months and more than 18 years of age and those who underwent ureterorenoscopy for indications other than the stones were excluded from the study. The children were managed on a fixed investigative and treatment protocol. The data from the Apollo Hospital New Delhi and Apollo Children's Hospital Chennai was analysed.

Results:

There were a total of thirty eight children, twenty in Chennai and eighteen in the New Delhi study. The mean age was 10.4 years and 8.5 years and the youngest child was14 months and 24 months in the Chennai and New Delhi group respectively. There was one conversion to open surgery in either group. Pneumatic lithotripter was used in majority of cases and holmium laser in select children.

Conclusion:

This is the largest Indian series of ureterorenoscopy for ureteric calculi in children. This study over nearly a decade confirms the safety and efficacy of this technique even in young children. In children less than five years, prestenting and delayed ureterorenoscopy allows safe endoscopic treatment of ureteric calculi.

Is urolithiasis in children associated with obesity or malnutrition?

BACKGROUND

Although it is known that obesity predisposes to urolithiasis, a tendency for malnutrition in children with urolithiasis owing to recurrent urinary infections and abdominal pain also makes sense.

AIMS

In this study, we aimed to determine the nutritional status of infants and children with urolithiasis, and to observe whether obesity or malnutrition is more prevalent in that population.

METHODS

One hundred eighty-seven children aged 4 months to 17 years (mean, 4.9 ± 4.4 years) with urolithiasis, and 278 age- and sex-matched children without any chronic diseases were included. Anthropometric evaluations, including weight and height standard deviation score (SDS), body mass index, and triceps and subscapular skinfold thickness (SFT), were performed.

RESULTS

Mean weight SDSs of the patients was statistically lower than that of the control subjects (P < .0001). Malnutrition rate was statistically higher in the patients with urolithiasis when evaluated according to weight SDS and percentiles of body mass index and SFT. When the age factor was taken into account, the percentage of malnutrition, determined by the percentiles of triceps and subscapular SFT measurements, was found to be higher in children younger than 2 years. Short stature was more prevalent in older children.

CONCLUSION

Malnutrition among children with urolithiasis is not as rare as thought previously. A careful anthropometric evaluation should be included in the clinical assessment of those children.

Epidemiology of pediatric urolithiasis

Pediatric urolithiasis has increased globally in the last few decades. There has been a change in the pattern of stone composition with an increase in the frequency of kidney stones and a decrease in bladder stones. The role of familial predisposition and environmental factors in pediatric urolithiasis is now better understood. Metabolic factors are more common in pediatric urolithiasis than in adult stone disease. This review updates on the epidemiology of pediatric urolithiasis with a focus on the changing trends in the stone disease, current spectrum of stone disease encountered in clinical practice, individual predisposition and the role of environmental factors in stone formation.

Changes in stone composition according to age and gender in Tunisian children

OBJECTIVE

Studies evaluating the influence of age and gender on the distribution of the various types of pediatric urinary calculi are scarce. The aim of this study was to highlight the modification of epidemiological characteristics of this pathology according to patients' sex and age.

PATIENTS AND METHODS

A total of 205 calculi (from 122 boys and 83 girls) were analyzed by infrared spectroscopy between 1993 and 2007; 54.6% of the patients were under 5 years.

RESULTS

Calcium oxalate was the predominant constituent in 54.7% of stones, followed by calcium phosphate and purines (14.6% each). We found a predominance of calcium oxalate in females (59.1% vs 50.8%), and a male preponderance for struvite stones (12.3% vs 1.2%). There was an increasing prevalence of calcium oxalate stones with age in both genders (42.9% in infants vs 59.3% in older children). Purine stones were predominant in 20% of cases, but prevalence decreased with age (28.6% in infants vs 18.5% in older children).

CONCLUSION

The increase in calcium oxalate stones in school-age children and the decrease in stones containing purines confirm a change in the etiology of urolithiasis according to age.

Pediatric urinary stone disease--does age matter?

PURPOSE

It has been proposed that younger children are less likely to pass renal calculi spontaneously, and that children younger than 10 years are more likely to have an identifiable metabolic abnormality and subsequently a higher risk of recurrence. We report our clinical outcomes in children with urinary calculi, specifically examining these factors.

MATERIALS AND METHODS

We performed a retrospective review of all pediatric patients diagnosed with renal or ureteral calculi at our institution between 2000 and 2007. Of 150 patients evaluated and treated during this period 80 (86 stones) had sufficient followup data to be included. Patients were divided into 2 groups according to age, namely 10 years or younger and older than 10 years. There were 39 patients in the younger group and 41 patients in the older group. Stone size and location, successful passage or intervention, recurrence and 24-hour urine metabolic study results were recorded.

RESULTS

Of the younger cohort stones were ureteral in 43% and renal in 57%. The opposite trend was seen in older patients, with 69% having ureteral and 31% having renal stones (p = 0.02). Mean stone size (greatest dimension) did not differ significantly between the older and younger groups (6.9 mm vs 5.5 mm, p = 0.17). Overall stone passage rate was 34% for younger and 29% for older patients (p = 0.65). No significant mean size differences in passed stones existed between the groups (3.2 mm vs 2.5 mm, p = 0.31). Overall younger vs older ureteral stone passage rate was 37% vs 41% (p = 0.58), and for renal stones it was 32% vs 0%. Stones recurred in 7 younger and 6 older patients.

CONCLUSIONS

Younger children were more likely to present with renal stones, while older children had more ureteral stones. Overall children 10 years old or younger are as likely to pass stones as older children. Renal stones are more likely to be successfully managed expectantly in younger children. Metabolic abnormalities and stone recurrences are observed at similar rates between younger and older children.

Genetic causes of hypercalciuric nephrolithiasis

Renal stone disease (nephrolithiasis) affects 3-5% of the population and is often associated with hypercalciuria. Hypercalciuric nephrolithiasis is a familial disorder in over 35% of patients and may occur as a monogenic disorder that is more likely to manifest itself in childhood. Studies of these monogenic forms of hypercalciuric nephrolithiasis in humans, e.g. Bartter syndrome, Dent's disease, autosomal dominant hypocalcemic hypercalciuria (ADHH), hypercalciuric nephrolithiasis with hypophosphatemia, and familial hypomagnesemia with hypercalciuria have helped to identify a number of transporters, channels and receptors that are involved in regulating the renal tubular reabsorption of calcium. Thus, Bartter syndrome, an autosomal disease, is caused by mutations of the bumetanide-sensitive Na-K-Cl (NKCC2) co-transporter, the renal outer-medullary potassium (ROMK) channel, the voltage-gated chloride channel, CLC-Kb, the CLC-Kb beta subunit, barttin, or the calcium-sensing receptor (CaSR). Dent's disease, an X-linked disorder characterized by low molecular weight proteinuria, hypercalciuria and nephrolithiasis, is due to mutations of the chloride/proton antiporter 5, CLC-5; ADHH is associated with activating mutations of the CaSR, which is a G-protein-coupled receptor; hypophosphatemic hypercalciuric nephrolithiasis associated with rickets is due to mutations in the type 2c sodium-phosphate co-transporter (NPT2c); and familial hypomagnesemia with hypercalciuria is due to mutations of paracellin-1, which is a member of the claudin family of membrane proteins that form the intercellular tight junction barrier in a variety of epithelia. These studies have provided valuable insights into the renal tubular pathways that regulate calcium reabsorption and predispose to hypercalciuria and nephrolithiasis.

Asymptomatic kidney stones in long-term survivors of childhood acute lymphoblastic leukemia

We hypothesized an association between renal calculi and bone mineral density (BMD) deficits, shown in adults, exists in survivors of childhood acute lymphoblastic leukemia (ALL). Thus, we analyzed the associations between quantitative computed tomography (QCT)-determined renal calcifications and clinical parameters (gender, race, age at diagnosis and age at the time of QCT), BMD, treatment exposures and Tanner stage. We investigated the associations between stone formation and nutritional intake, serum and urinary calcium and creatinine levels, and urinary calcium/creatinine ratio. Exact chi(2)-test was used to compare categorical patient characteristics, and the Wilcoxon-Mann-Whitney test to compare continuous measurements. Of 424 participants, 218 (51.4%) were males; 371 (87.5%) were nonblack. Most (n=270; 63.7%) were >or=3.5 years at ALL diagnosis. Mean (s.d.) and median (range) BMD Z-scores of the entire cohort were -0.4 (1.2) and -0.5 (-3.9 to 5.1), respectively. Nineteen participants (10 males; 10 Caucasians) had kidney stones (observed prevalence of 4.5%; 19/424) with a significant negative association between stone formation and body habitus (body mass index, P=0.003). Stone formation was associated with treatment protocol (P=0.009) and treatment group (0.007). Thus, kidney stones in childhood ALL survivors could herald the future deterioration of renal function and development of hypertension. Long-term follow-up imaging may be warranted in these patients to monitor for progressive morbidity.

[Urolithiasis in children--rational diagnosis, therapy, and metaphylaxis]

With a proportion of 1-5%, children constitute only a small number of all patients with urolithiasis. Nevertheless, pediatric stone disease is an important health care problem because of the high recurrence rate and the threat of progredient renal function impairment with consecutive loss of quality of life. Modern therapies, especially extracorporeal shock wave lithotripsy (ESWL), ureteroscopy (URS), and percutaneous nephrolithotomy (PCNL), have caused a revolution in the operative treatment spectrum. Open surgery is required for stone removal only rarely, such as for the simultaneous repair of urinary tract anomalies. The minimally invasive modalities of modern stone therapy - mainly ESWL as the treatment of first choice - have led to widespread disregard of stone metaphylaxis. The important principle that says an urinary stone is just a symptom and not the cause of the disease is often forgotten. So it must be noted that despite the high standard of care in Germany, not all problems regarding urinary stone disease are being resolved, particularly in childhood. This article presents the current knowledge of the most important aspects of stone therapy and the methods of treatment in children.

Urinary metabolic evaluations in solitary and recurrent stone forming children

PURPOSE

We have previously reported a high rate of urinary metabolic abnormalities in stone forming children compared to normal controls. At our institution a 24-hour urine evaluation is initiated after the first stone episode in children, to measure stone risk indices. The purpose of this study was to determine which children are at the greatest risk for recurrent stone formation.

MATERIALS AND METHODS

A retrospective cohort study was performed to assess urinary metabolic profiles in children with urolithiasis. In all patients 24-hour urine collections were performed and evaluated elsewhere. Urine chemistry assessments such as calcium and citrate were adjusted for creatinine and weight. Calcium oxalate supersaturation was measured. Patients were stratified as solitary or recurrent stone formers based on review of the medical record. Univariate analysis between means was performed with a 2-tailed t test.

RESULTS

A total of 148 samples from 88 solitary stone formers and 84 samples from 51 recurrent stone formers were evaluated. Age and gender were well matched between the 2 groups. Timed urinary calcium levels referenced to creatinine and citrate were significantly higher in patients with recurrent stones. Supersaturation levels of calcium oxalate were higher in recurrent stone formers but did not reach statistical significance.

CONCLUSIONS

There are significant differences in 24-hour urinary calcium levels between solitary and recurrent calcium stone forming children. A patient with increased urinary calcium indices on a 24-hour specimen may benefit from more aggressive initial dietary and pharmacological treatment to prevent stone recurrence.

Epidemiology and risk factors in urolithiasis

Stone formation in the urinary tract affects about 5-10% of the population in industrialized countries, although it is very rare in other countries such as Greenland or Japan. The high incidence and recurrence rate contribute to making the urolithiasis a serious social problem. Nowadays, urolithiasis must be considered a 'disease in evolution' for several reasons, such as epidemiological changes, evolution of the methods used for diagnosis, and the treatment and prophylaxis of the population considered 'at risk' of stone disease. Some features of stone disease have changed over the last few years due to many social, economical and cultural factors that are described here. The increased prevalence of small urinary calculi has brought about a change in clinical symptoms, with frequent episodes of renal-ureteral colic, persistent pain and hydronephrosis. Similarly, the presence of residual fragments after extracorporeal shock wave lithotripsy has induced a radical change in the management of small calculi through the use of mini-invasive surgical techniques.

Management of Cystinuria

Cystinuria is a monogenic disorder in which there is a transepithelial transport defect of di-basic amino acids, including cystine, ornithine, lysine, and arginine (COLA). This results in diminished reabsorption of these amino acids in both the intestine and renal proximal tubule. This article describes the disorder, reviews the mechanisms of normal COLA renal transport, and summarizes issues related to the disorder, such as the role of mutations, associated diseases, clinical manifestations, therapies, the renal impact, and handling of pediatric patients.