Pediatric urolithiasis: developing nation perspectives

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.

Endourology Methods in Pediatric Population for Kidney Stones Located in Lower Calyx: FlexURS vs. Micro PCNL (MicroPERC®)

Kidney stone disease in children is always a therapeutic challenge. It is a multifactorial condition and it should be approached, diagnosed and treated as such. One of the biggest challenges is kidney stones located in the lower renal calyx. There are currently three main surgical techniques to treat this condition: ESWL-Extracorporeal Shock Wave Lithotripsy, RIRS-Retrograde IntraRenal Surgery, and PCNL-PerCutaneous Nephro-Lithotripsy. In pediatric population, the most frequently used method is ESWL, and in the event of failure, endoscopic procedures are the second-best choice. In this article, a sample of 53 children admitted to a tertiary medical center was examined. Thirty-eight of those children underwent flexible URS, while the remaining 15-micro PCNL. The average size of the deposit in the former group was 12.2 mm, against 13.5 mm in the latter. The full Stone Free Rate (SFR) was achieved in RIRS at 84.21 and 86.7% in percutaneous nephrolithotripsy. Flexible ureterorenoscopy and MicroPERC are two comparably effective methods for treating lower calyx stones of any size. However, according to our data, flexible ureterorenoscopy carries a lower risk of complications and inpatient care (with the mean of 3 days). The learning curve for these procedures in pediatric urology is long and relies on a limited number of patients. The number of pediatric patients qualifying for these procedures is restricted also due to the high efficacy of extracorporeal shock wave lithotripsy in pediatric population. Radiation exposure is an important factor in every endoscopy procedure and should never exceed the limits set in the ALARA protocol. ESWL remains to this day the treatment of choice for stone disease in children and can be performed under ultrasound control. For many parents, it is a first-choice treatment preference for their child due to its greater apparent safety, although data on this remains insufficient. Prospective, randomized, multicenter trials are definitely needed.

Efficacy of transurethral cystolithotripsy assisted by percutaneous evacuation and the benefit of genetic analysis in a pediatric cystinuria patient with a large bladder stone

Cystinuria is an inherited disease, and the defective reabsorption of cysteine causes often requires operations for large urinary stones from childhood. It is rare to be diagnosed only with bladder stones and essential to select an operative procedure according to the age of the patient and the size of the stone.

We report the case of a 2-year-old boy with cystinuria diagnosed with a large bladder stone and investigate the efficacy of transurethral cystolithotripsy assisted by percutaneous evacuation. Additional genetic analysis for the entire family revealed benefit for the life-span treatment of cystinuria.

Management of staghorn stones in special situations

Staghorn stones have always been a challenge for urologists, especially in some special situations, such as horseshoe kidney, ectopic kidney, paediatric kidney, and solitary kidney. The treatment of these staghorn stones must be aggressive because they can lead to renal function loss and serious complications. The gold-standard management for staghorn stones is surgical treatment with the aim of clearing the stones and preserving renal function. Treatment methods for staghorn stones have developed rapidly, such as extracorporeal shock wave lithotripsy, retrograde intrarenal surgery, percutaneous nephrolithotomy and laparoscopy and open surgery. Whether the standard procedures for staghorn stones can also apply to these stones in special situations is still not agreed upon. The decision should be made individually according to the circumstances of the patient. In this review, we evaluates the previous studies and comments on the management of staghorn stones under special situations in the hope of guiding the optimal choice for urologists.

Medical and surgical interventions for the treatment of urinary stones in children

BACKGROUND

Urolithiasis is a condition where crystalline mineral deposits (stones) form within the urinary tract. Urinary stones can be located in any part of the urinary tract. Affected children may present with abdominal pain, blood in the urine or signs of infection. Radiological evaluation is used to confirm the diagnosis, to assess the size of the stone, its location, and the degree of possible urinary obstruction.

OBJECTIVES

To assess the effects of different medical and surgical interventions in the treatment of urinary tract stones of the kidney or ureter in children.

SEARCH METHODS

We searched the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid) as well as the World Health Organization International Clinical Trials Registry Platform Search Portal and ClinicalTrials.gov. We searched reference lists of retrieved articles and conducted an electronic search for conference abstracts for the years 2012 to 2017. The date of the last search of all electronic databases was 31 December 2017 and we applied no language restrictions.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) and quasi-RCTs looking at interventions for upper urinary tract stones in children. These included shock wave lithotripsy, percutaneous nephrolithotripsy, ureterorenoscopy, open surgery and medical expulsion therapy for upper urinary tract stones in children aged 0 to 18 years.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures according to Cochrane guidance. Two review authors independently searched and assessed studies for eligibility and conducted data extraction. 'Risk of bias' assessments were completed by three review authors independently. We used Review Manager 5 for data synthesis and analysis. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

We included 14 studies with a total of 978 randomised participants in our review, informing eight comparisons. The studies contributing to most comparisons were at high or unclear risk of bias for most domains.Shock wave lithotripsy versus dissolution therapy for intrarenal stones: based on one study (87 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on stone-free rate (SFR), serious adverse events or complications of treatment and secondary procedures for residual fragments.Slow shock wave lithotripsy versus rapid shock wave lithotripsy for renal stones: based on one study (60 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on SFR, serious adverse events or complications of treatment and secondary procedures for residual fragments.Shock wave lithotripsy versus ureteroscopy with holmium laser or pneumatic lithotripsy for renal and distal ureteric stones: based on three studies (153 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on SFR, serious adverse events or complications of treatment and secondary procedures.Shock wave lithotripsy versus mini-percutaneous nephrolithotripsy for renal stones: based on one study (212 participants), SWL likely has a lower SFR (RR 0.88, 95% CI 0.80 to 0.97; moderate quality evidence); this corresponds to 113 fewer stone-free patients per 1000 (189 fewer to 28 fewer). SWL may reduce severe adverse events (RR 0.13, 95% CI 0.02 to 0.98; low quality evidence); this corresponds to 66 fewer serious adverse events or complications per 1000 (74 fewer to 2 fewer). Rates of secondary procedures may be higher (RR 2.50, 95% CI 1.01 to 6.20; low-quality evidence); this corresponds to 85 more secondary procedures per 1000 (1 more to 294 more).Percutaneous nephrolithotripsy versus tubeless percutaneous nephrolithotripsy for renal stones: based on one study (23 participants) and consistently very low quality evidence, we are uncertain about the effects of percutaneous nephrolithotripsy on SFR, serious adverse events or complications of treatment and secondary procedures.Percutaneous nephrolithotripsy versus tubeless mini-percutaneous nephrolithotripsy for renal stones: based on one study (70 participants), SFR are likely similar (RR 1.03, 95% CI 0.93 to 1.14; moderate-quality evidence); this corresponds to 28 more per 1,000 (66 fewer to 132 more). We did not find any data relating to serious adverse events. Based on very low quality evidence we are uncertain about secondary procedures.Alpha-blockers versus placebo with or without analgesics for distal ureteric stones: based on six studies (335 participants), alpha-blockers may increase SFR (RR 1.34, 95% CI 1.16 to 1.54; low quality evidence); this corresponds to 199 more stone-free patients per 1000 (94 more to 317 more). Based on very low quality evidence we are uncertain about serious adverse events or complications and secondary procedures.

AUTHORS' CONCLUSIONS

Based on mostly very low-quality evidence for most comparisons and outcomes, we are uncertain about the effect of nearly all medical and surgical interventions to treat stone disease in children.Common reasons why we downgraded our assessments of the quality of evidence were: study limitations (risk of bias), indirectness, and imprecision. These issues make it difficult to draw clinical inferences. It is important that affected individuals, clinicians, and policy-makers are aware of these limitations of the evidence. There is a critical need for better quality trials assessing patient-important outcomes in children with stone disease to inform future guidelines on the management of this condition.

Update on Surgical Management of Pediatric Urolithiasis

Urolithiasis has always been a fascinating disease, even more so in children. There are many intriguing facets to this pathology. This article is a nonsystematic review to provide an update on the surgical management of pediatric urolithiasis. It highlights the pros and cons of various minimally invasive surgical options such as extracorporeal shockwave lithotripsy (ESWL), retrograde intrarenal surgery (RIRS), percutaneous nephrolithotomy (PCNL), laparoscopy, and robotics. This article also describes the various intracorporeal disintegration technologies available to fragment the stone, including the newer advancements in laser technology. It also emphasizes the cost considerations especially with reference to the emerging economies. Thus, this manuscript guides how to select the least-invasive option for an individual patient, considering age and gender; stone size, location, and composition; and facilities and expertise available.

High prevalence of pediatric urinary tract stones in Xinjiang Uyghur

The aim of the study was to report the characteristics of urolithiasis in Uyghur patients from Xinjiang, China. The composition of stones collected from 1863 patients in the Uyghur region of Xinjiang was analyzed. The median age of patients was 17 years [25th and 75th percentiles: 2, 36]. The stones were delivered by 1299 males (69.7%) and 564 females (30.3%). Calcium oxalate was the predominant stone component in 42.1% of the patients, followed by ammonium urate in 20.6%. Females had formed more stones of magnesium ammonium phosphate 8.9 vs. 5.6% (p = 0.010) and carbonate apatite 6.2 vs. 3.3% (p = 0.004). In contrast uric acid was more common in males than in females; 21.6 vs. 15.1% (p = 0.001). In this series, pediatric patients (age range 0-18) were more likely to present with a stone (51.5%, p < 0.001). Moreover, the largest number of pediatric stones was recorded in children 1-2 years old (37.9%, p < 0.001). The occurrence of ammonium urate stones was extremely high (52.4%) in children with an age below 1 year. There was a downward trend for ammonium urate with age in both children and adults (p for trend < 0.001, respectively). In contrast the frequency of uric acid declined with age in pediatric patients, but increased in adults (p for trend < 0.001, respectively). This study provides a basis for further considerations on the management of Xinjiang Uyghur patients and emphasize the severity of pediatric stone problems.

Medical and surgical interventions for the treatment of urinary stones in children

BACKGROUND

Urolithiasis is a condition where crystalline mineral deposits (stones) form within the urinary tract. Urinary stones can be located in any part of the urinary tract. Affected children may present with abdominal pain, blood in the urine or signs of infection. Radiological evaluation is used to confirm the diagnosis, to assess the size of the stone, its location, and the degree of possible urinary obstruction.

OBJECTIVES

To assess the effects of different medical and surgical interventions in the treatment of urinary tract stones of the kidney or ureter in children.

SEARCH METHODS

We searched the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE (Ovid), Embase (Ovid) as well as the World Health Organization International Clinical Trials Registry Platform Search Portal and ClinicalTrials.gov. We searched reference lists of retrieved articles and conducted an electronic search for conference abstracts for the years 2012 to 2017. The date of the last search of all electronic databases was 31 December 2017 and we applied no language restrictions.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) and quasi-RCTs looking at interventions for upper urinary tract stones in children. These included shock wave lithotripsy, percutaneous nephrolithotripsy, ureterorenoscopy, open surgery and medical expulsion therapy for upper urinary tract stones in children aged 0 to 18 years.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures according to Cochrane guidance. Two review authors independently searched and assessed studies for eligibility and conducted data extraction. 'Risk of bias' assessments were completed by three review authors independently. We used Review Manager 5 for data synthesis and analysis. We used the GRADE approach to assess the quality of evidence.

MAIN RESULTS

We included 14 studies with a total of 978 randomised participants in our review, informing eight comparisons. The studies contributing to most comparisons were at high or unclear risk of bias for most domains.Shock wave lithotripsy versus dissolution therapy for intrarenal stones: based on one study (87 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on stone-free rate (SFR), serious adverse events or complications of treatment and secondary procedures for residual fragments.Slow shock wave lithotripsy versus rapid shock wave lithotripsy for renal stones: based on one study (60 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on SFR, serious adverse events or complications of treatment and secondary procedures for residual fragments.Shock wave lithotripsy versus ureteroscopy with holmium laser or pneumatic lithotripsy for renal and distal ureteric stones: based on three studies (153 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on SFR, serious adverse events or complications of treatment and secondary procedures.Shock wave lithotripsy versus mini-percutaneous nephrolithotripsy for renal stones: based on one study (212 participants), SWL likely has a lower SFR (RR 0.88, 95% CI 0.80 to 0.97; moderate quality evidence); this corresponds to 113 fewer stone-free patients per 1000 (189 fewer to 28 fewer). SWL may reduce severe adverse events (RR 0.13, 95% CI 0.02 to 0.98; low quality evidence); this corresponds to 66 fewer serious adverse events or complications per 1000 (74 fewer to 2 fewer). Rates of secondary procedures may be higher (RR 2.50, 95% CI 1.01 to 6.20; low-quality evidence); this corresponds to 85 more secondary procedures per 1000 (1 more to 294 more).Percutaneous nephrolithotripsy versus tubeless percutaneous nephrolithotripsy for renal stones: based on one study (23 participants) and consistently very low quality evidence, we are uncertain about the effects of SWL on SFR, serious adverse events or complications of treatment and secondary procedures.Percutaneous nephrolithotripsy versus tubeless mini-percutaneous nephrolithotripsy for renal stones: based on one study (70 participants), SFR are likely similar (RR 1.03, 95% CI 0.93 to 1.14; moderate-quality evidence); this corresponds to 28 more per 1,000 (66 fewer to 132 more). We did not find any data relating to serious adverse events. Based on very low quality evidence we are uncertain about secondary procedures.Alpha-blockers versus placebo with or without analgesics for distal ureteric stones: based on six studies (335 participants), alpha-blockers may increase SFR (RR 1.34, 95% CI 1.16 to 1.54; low quality evidence); this corresponds to 199 more stone-free patients per 1000 (94 more to 317 more). Based on very low quality evidence we are uncertain about serious adverse events or complications and secondary procedures.

AUTHORS' CONCLUSIONS

Based on mostly very low-quality evidence for most comparisons and outcomes, we are uncertain about the effect of nearly all medical and surgical interventions to treat stone disease in children.Common reasons why we downgraded our assessments of the quality of evidence were: study limitations (risk of bias), indirectness, and imprecision. These issues make it difficult to draw clinical inferences. It is important that affected individuals, clinicians, and policy-makers are aware of these limitations of the evidence. There is a critical need for better quality trials assessing patient-important outcomes in children with stone disease to inform future guidelines on the management of this condition.

Metabolic evaluation of children with urolithiasis

Aim:

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

Materials and Methods:

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

Results:

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

Conclusion:

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

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

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

Endemic bladder calculi in children

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

Silodosin in the treatment of distal ureteric stones in children: A prospective, randomised, placebo-controlled study

Objectives

To evaluate the possible role of silodosin (a highly selective α_1A-adrenoceptor antagonist) in facilitating the passage of distal ureteric stones (DUS) in children, as the role of α-blockers as medical expulsive therapy is well known in adults.

Patients and methods

In all, 40 paediatric patients (27 boys and 13 girls) diagnosed with unilateral, single, radiopaque DUS of <10 mm were included in the study. Their mean (SD, range) age was 8.1 (2.7, 5–17) years. The patients were randomly divided into two groups: Group A, received silodosin 4 mg as a single bedtime dose; and Group B, received placebo as a single bedtime dose. Ibuprofen was prescribed to both groups on-demand for pain episode relief. Patients were followed up biweekly for 4 weeks. The stone expulsion time and rate, pain episodes, analgesic use, and any adverse effects were recorded.

Results

The mean (SD) stone size in Group A was 6.6 (1.7) mm and in Group B was 6.7 (1.4) mm (P = 0.4). Two patients were lost to follow-up (one from each group), and one patient in Group A refused to complete the study. The stone-free rate at end of the 4-week treatment period was 88.8% in Group A vs 73.6% in Group B (P = 0.4). The mean (SD) stone expulsion time was 7.0 (4.3) vs 10.4 (4.7) days in groups A and B, respectively (P = 0.02). The mean (SD) number of pain episodes requiring ibuprofen was 2.3 (1.4) vs 4.7 (2.6) episodes in groups A and B, respectively (P < 0.001). Adverse effects (headache and dizziness) were recorded in three patients (16.7%) in Group A, which were mild and none of them discontinued treatment, whilst no adverse effects were recorded in Group B.

Conclusions

The data in the present study show that silodosin can be safely used in the treatment of DUS in children for decreasing time to stone expulsion, pain episodes, and analgesic requirement.

Urinary tract stone development in patients with myelodysplasia subjected to augmentation cystoplasty

Patients with myelodysplasia who have undergone augmentation cystoplasty are at risk for urinary tract stones. We sought to determine the incidence and risk factors for stone development in this population. The charts of 40 patients with myelodysplasia who have undergone augmentation cystoplasty were reviewed. None had a prior history of urinary tract stones. All patients were seen on an annual basis with plain abdominal imaging, renal ultrasonography, and laboratory testing. Statistical analysis included a multivariable bootstrap resampling method and Student's t-test. Fifteen (37.5%) patients developed stones, 14 with bladder stones and 1 with a solitary renal stone, at a mean of 26.9 months after augmentation. Five (33.3%) developed recurrent bladder stones. The patient with a renal stone never developed a bladder stone. The mean follow-up for the stone formers was 117.2 months and for non-stone formers was 89.9 months. The stone incidence per year was 6.8%. Risk factors included a decline in serum chloride after augmentation (P = .02), female sex, younger age at time of augmentation, longer time period since augmentation, and bowel continence. A significant proportion of patients with myelodysplasia subjected to augmentation cystoplasty develop urinary tract stones, predominantly in the bladder. Dehydration may play a role in development of lower urinary tract stones as the decline in serum chloride suggests contraction alkalosis, which could lead to constipation and improved bowel continence. Therefore, improved hydration should be a goal in this cohort.

What do we know about pediatric renal microlithiasis?

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

Water intake and urinary hydration biomarkers in children

BACKGROUND/OBJECTIVES

The aims of the study were as follows: (1) examine fluid intake and urinary hydration markers of children in Greece, (2) determine the calculated relative risk of hypohydration in children who did not meet the recommendations for daily water intake provided by the Institute of Medicine and the European Food Safety Authority compared with those who did and (3) analyze the efficacy of the recommendations as a method to achieve euhydration in children.

SUBJECTS/METHODS

One hundred and fifty Greek boys and girls (age 9-13) recorded their fluid intake for 2 consecutive days. A 24-h urine collection was obtained during the second day. Fluid intake records were analyzed for total water intake from fluids (TWI-F), and urine samples were analyzed for osmolality, color, specific gravity and volume. Urine osmolality ⩾800 mmol/kg H₂O was defined as hypohydration.

RESULTS

Water intake from fluids was 1729 (1555-1905) and 1550 (1406-1686) ml/d for boys and girls, respectively. Prevalence of hypohydration was 33% (44% of boys, 23% of girls). Children who failed to meet TWI-F recommendations demonstrated a risk of hypohydration that was 1.99-2.12 times higher than those who met recommendations (P⩽0.01). Boys between 9 and 13 years displayed urine osmolality of 777 (725-830) mmol/kg, and urine specific gravity of 1.021 (1.019-1.022), which was higher than those in girls between 9-13 years (P⩽0.015), and >27% were classified as hypohydrated despite meeting water intake recommendations.

CONCLUSIONS

Failure to meet TWI-F guidelines increased calculated relative risk of hypohydration in children. Boys between 9 and 13 years are at greater hazard regardless of meeting guidelines and may require greater water intake to avoid elevated urine concentration and ensure adequate hydration.

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

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

Metabolic disturbances in Chinese children with urolithiasis: a single center report

Urinary stones and urine composition are the first steps in the process of recurrence prevention, but data concerning the association between the two compositions are scarce in Chinese children with urolithiasis. We retrospectively analyzed the records of children (age range 0-18 years) with urolithiasis in our center between March 2004 and December 2013. Stone analysis was carried out in 382 children and 24-hour urine analysis in 80 children. Analysis of both stone and 24-hour urine composition was completed in 56 children. Stone samples were analyzed by Fourier transform-infrared spectrometry. The major stone constituents were calcium oxalate (78.8 %). Of 80 children with 24 h urine analysis, only 2.5 % were without urinary metabolic abnormalities. Hypocitraturia was recorded in 97.5 %, high sodium excretion in 50.0 %, cystinuria in 48.7 %, hypercalciuria in 18.8 %, small urine volumes in 12.5 %, hyperoxaluria in 5.0 % and hyperuricosuria in 1.3 %. Interestingly, higher urine volumes were recorded in girls than in boys (73.2 ± 58.5 vs 51.3 ± 45.3 mL/kg, p = 0.036). Urine sodium (p = 0.002) and oxalate (p = 0.004) were significantly higher in children >9 year old. Moreover, compared with calcium oxalate stone formers, the urine volume (p = 0.040), citrate (p = 0.007) and cystine (p = 0.004) were higher in patients with cystine stones. Hypocitraturia was the common abnormality among Chinese children with urolithiasis. The surprisingly high incidence of cystinuria is of note.

Risk factors for formation of steinstrasse after extracorporeal shock wave lithotripsy for pediatric renal calculi: a multivariate analysis model

OBJECTIVES

To define various stone, renal and therapy factors that could affect steinstrasse (SS) formation after extracorporeal shock wave lithotripsy (SWL) for pediatric kidney stones. Thus, SS could be anticipated and prophylactically avoided

METHODS

From January 1999 through December 2012, 317 children underwent SWL with Dornier Lithotripter S for the treatment of renal stones. Univariate and multivariate statistical analyses of patients, stones and therapy characteristics in relation to the incidence of SS were performed to detect the factors that had a significant impact on SS formation.

RESULTS

The overall incidence of SS was 8.5%. The steinstrasse was in the pelvic ureter in 74.1% of the cases, lumbar ureter in 18.5% and iliac ureter in 7.4%. Steinstrasse incidence significantly correlated with stone size, site and age of child. Steinstrasse was more common with increasing stone length and stones located in renal pelvis or upper calyx with the age below 4 years. A statistical model was constructed to estimate the risk of steinstrasse formation accurately. The equation for logistic regression is Z = -4.758 + B for age + B for size stone X length in mm + B for stone site.

CONCLUSIONS

The stone size, site and age are the most important risk factors responsible for SS formation in children. Our regression analysis model can help with prospective identification of children who will be at risk of SS formation. Those children at high risk of SS formation should be closely monitored or treated by endoscopic maneuvers from the start.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Extracorporeal shockwave lithotripsy under sedoanalgesia for treatment of kidney stones in infants: a single-center experience with 102 cases

OBJECT

We present the efficacy of shockwave lithotripsy (SWL) therapy administered with sedoanalgesia in infants with kidney stones.

MATERIALS AND METHODS

We enrolled 102 patients aged 5-24 months who had kidney stones and received SWL therapy under sedoanalgesia using a Siemens Lithostar Modularis device. Patient and stone characteristics, therapy parameters, pain score, complications, discharge time, and follow-ups were registered and evaluated. Pain score was assessed using a Neonatal Infant Pain Score (NIPS). Postanesthetic discharge scoring system (PADSS) was used for the assessments of postprocedural discharge procedure.

RESULTS

Mean age of the patients was 17.2 ± 6.3 months (5-24 months). Mean stone size was 7.9 ± 3.3 mm (5-23 mm). The most common concomitant metabolic disorders were hypercalciuria and hypocitraturia. The stone-free rates of the infants were 70.6, 87.3, and 99.1 % after the first, second, and third sessions of SWL therapy, respectively. The mean NIPS scores procedure during, and at 1 h after SWL procedure were determined as 0.24 ± 0.45 and 0.34 ± 0.47, respectively. There was no statistically significant difference between two pain score values (P = 0.114). The mean discharge time of patients after the SWL procedure were 108.6 ± 27.9 min. Forty-two patients (41.1 %) were followed up. The follow-up period varied between 8 and 48 months (mean 19.5 months); none of those patients showed evidence of diabetes mellitus, hypertension, or renal function impairment.

CONCLUSIONS

SWL therapy under sedoanalgesia is a safe and efficient treatment modality that can be administered with low complication rates and high stone-free rates in the treatment of renal stones in infants.

Evolution of pediatric urology at sindh institute of urology and transplantation

Sindh Institute of Urology and Transplantation was started in 1972 as an eight bedded department of genitourinary surgery in a government hospital by its pioneer and present director Syed Adib ul Hassan Rizvi. Responding to the socioeconomic dynamics and the needs of the patient population the facility grew into the largest tertiary care Urology, Nephrology, and Transplant center of south Asia. One of the salient components has been the evolution of the Department of Pediatric Urology, which in itself has shown a tremendous growth into an internationally recognized center for pediatric urology services taking care of all aspects including center of excellence for pediatric stone disease. The guiding mission of this institute remains to provide free medical services at zero cost without any discrimination to all who come to its doorstep and matching with high standard of care without compromising their dignity and self-respect. This institute highlights the fact that lack of resources is no excuse and is a role model for developing countries, where national and international support, motivation, and cooperation can offer more advanced and better quality medical services to our children.

[Urolithiasis in childhood]

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

Metabolic risk factors and the effect of metaphylaxis in pediatric stone disease with hypocitraturia

To describe the metabolic risk factors and investigate the effect of prophylaxis based on these factors on long-term recurrence of urolithiasis in pediatric patients with hypocitraturia. One-hundred and twenty-nine pediatric patients who underwent percutaneous nephrolithotomy between January 2008 and June 2011 were evaluated for metabolic risk factors. The patients with hypocitraturia were enrolled in this study and the data were analyzed using statistical methods for a mean period of 2 years for metabolic abnormalities, stone type, and the effect of potassium citrate prophylaxis on stone recurrence. A 24-h urine metabolite analysis revealed one or more metabolic risk factors in 115 (89.2 %) of the patients, whereas 14 (10.8 %) of the patients had no metabolic abnormalities. Eighty-two (63.5 %) of 129 patients had hypocitraturia. Of them, 43 (52 %) were male and 39 (48 %) were female, with a mean age of 9.7 ± 4.9 and 6.7 ± 4.4 (1-16) years, respectively(p = 0.102). Thirty-five (42.7 %) had pure hypocitraturia, and 47 (57.3 %) had two or more metabolic abnormalities. The most common dual metabolic abnormality was hypocitraturia and hypomagnesuria. Seventy-one patients (87 %) with hypocitraturia received medical prophylaxis and continued regularly, whereas 11 (13 %) patients did not receive medical prophylaxis despite being advised to do so. After a mean follow-up of 26.5 ± 9.4 months, the rate of recurrence was 1.4 % in the patients with hypocitraturia who continued prophylaxis and occurred in all of the patients who did not receive prophylaxis (p < 0.001). Calcium oxalate stones (95.2 %) were the most commonly found stones in the stone analysis. Detailed clinical and laboratory evaluations should be performed in children with urolithiasis. Appropriate prophylactic treatment as potassium citrate, should be given to prevent reformation of stones in patient with hypocitraturia.

Urinary stone disease in the first year of life: is it dangerous?

PURPOSE

We have evaluated the clinical, radiological and metabolic features of infantile urolithiasis (UL).

MATERIALS AND METHODS

We have reviewed the medical records of 93 children who were diagnosed as having UL before 1 year of age. We recorded patient demographics, the age at diagnosis, presenting symptoms, family history, the localizations and dimensions of stones, urinary metabolic examinations, as well as physical, laboratory, and radiologic findings. Our secondary objective was to compare some features of this group with those of older children with UL followed-up in the same clinic which were previously reported.

RESULTS

We evaluated 93 children referred to our pediatric nephrology clinics. A family history of UL was 56.2 % in the study group. Resolution of stones was observed in 30.1 % of the cases. Urinary tract infections (UTIs) were detected in 65.9 % of females and 46.2 % of males. At least one urinary metabolic abnormality was found in 79.5 % of all the children. Most commonly seen metabolic abnormality was hypercalciuria. In all patients stones were located in kidneys except one infant who had an ureteral stone together with a kidney stone. Fifteen (16.1 %) children had an accompanying systemic disorder.

CONCLUSIONS

Among pediatric urinary stone diseases infantile UL can be regarded as a separate clinical entity. Coexistence of systemic disorders and anatomic anomalies at high frequencies may indicate a role of distinct pathogenetic mechanisms. In addition, high rates of UTIs and metabolic abnormalities in this age group justify screening for these parameters during follow-up of these children.

Urinary calcium and uric acid excretion in children with vesicoureteral reflux

Urolithiasis is relatively common in children, and identifiable predisposing factors for stone formation, including metabolic and structural derangements, can be established in most cases. Vesicoureteral reflux (VUR) is a common cause of kidney stone formation. The pathophysiological mechanism of urolithiasis in reflux is related to urinary tract infection and urinary stasis, both of which promote urinary crystal formation, but metabolic causes, such as crystallurias (mostly hypercalciuria), may also be involved in this process. However, few studies on urinary calcium and uric acid excretion in children with VUR have been conducted. We have studied the frequency of hypercalciuria and hyperuricosuria in children with VUR and compared the results with those from a control group. The VUR group comprised 108 children with VUR (19 boys, 89 girls; age range 3 months to 12 years), and the control group comprised 110 healthy children without any history of reflux or urinary tract infection (30 boys, 80 girls; age range 2 months to 12 years). Fasting urine was analyzed for the calcium/creatinine (Ca/Cr) and uric acid/creatinine (UA/Cr) ratios. Hypercalciuria was more frequently diagnosed in the VUR patients than in the control group (21.3 vs. 3.6%; P = 0.0001). Significant differences between the two groups were also found for the mean Ca/Cr and UA/Cr ratios (P = 0.0001 and P = 0.0001, respectively). No differences were found in the urinary Ca/Cr or UA/Cr ratios related to VUR grading or unilateral/bilateral VUR in the patient group, with the exception of those for hypercalciuria and mild VUR (P = 0.03). The association of urinary stones and microlithiasis in the VUR group was 29.6%. Our results demonstrate that the frequency of hypercalciuria and hyperuricosuria was higher in pediatric patients with VUR than in healthy children. Knowing this relationship, preventive and therapeutic interventions for stone formation in VUR could be greatly expanded.

Percutaneous nephrolithotomy for pediatric urolithiasis

Pediatric urolithiasis is a management dilemma as a number of treatment options are available such as shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), and retrograde intrarenal surgery (RIRS). PCNL offers good clearance rates in a single hospital stay. The concerns with PCNL include the use of large instrument in pediatric kidneys, parenchymal damage and the associated effects on renal function, radiation exposure with fluoroscopy, and the risk of major complications including sepsis and bleeding. Evolution of pediatric PCNL technique such as miniaturization of instruments, limitation of tract size and advanced intracorporeal lithotripters have resulted in this technique being widely utilized for achieving stone-free status in appropriate patients. Many of the patients in our country come from remote areas thereby requiring special considerations during treatment. This also necessitates complete clearance in a single shorter hospital stay. PCNL appears to be the optimal option available in this scenario. The literature suggests that even complex and staghorn calculi can be tackled with this approach. The choice of the method to gain access is a matter of experience and personal preference. Ultrasound offers the advantage of visualization of spleen, liver and avoids injury. Miniaturization of instruments, particularly smaller nephroscopes and the potential to use lasers will decrease the morbidity and improve the clearance rates further. In this article, we analyze the management of pediatric urolithiasis with PCNL. We discuss our technique and analyze the results, complications and technique mentioned in the contemporary literature.

Evaluation of children with urolithiasis

Objectives:

To describe an evaluation protocol for pediatric stone formers for risk assessment and management strategies.

Materials and Methods:

Between 2002-2006, 2618 children of age three months to 15 years were evaluated for stone disease. Evaluation included demographics, history, anthropometry, diet, ultrasound, X-ray KUB, IVU, blood and 24h urine chemistry and cultures. Stones were analyzed by IR spectroscopy.

Results:

The median age was seven years with a M:F ratio of 2.2:1. Of the 2618 patients, 2216 presented with normal renal function and 402 with renal failure. Main symptoms were abdominal pain (33%), flank pain (38%) and fever (38%). Renal failure patients also had shortness of breath (38%) and oligo-anuria (26%). Children were malnourished with height and weight deficits in 65% and 76% respectively. Diet was low in protein (74%), calcium (55%) and fluids in (55%), high in oxalate (55%), sodium (39%), purines (42%) and refined sugar (41%). Overall urine cultures were positive in 1208 (46%) with E. coli (38%) and Klebsiella (8%).

Stone distribution was renal in 64%, ureter in 8%, bladder in 18%, bilateral in 40% and multiple sites in 18%. Median stone size was >1.5-2.0 cm. The frequency of compounds in stones was ammonium urate (58%), calcium oxalate (63%), uric acid (6%), calcium phosphate (12%) and struvite (8%). Metabolic abnormalities included hypovolumia (31%), hypocitraturia (87%), hyperoxaluria (43%) and hyperuricosuria (26%). Dietary and medical treatment corrected risk factors in two-thirds of patients with a recurrence rate of about 1.15%.

Conclusion:

An evaluation based on history, imaging, diet, metabolic analysis and stone type can help to tailor management strategies.

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.

Open surgical management of pediatric urolithiasis: A developing country perspective

Objectives

To describe decision factors and outcome of open surgical procedures in the management of children with stone.

Materials and Methods

Between January 2004 and December 2008, 3969 surgical procedures were performed in 3053 children with stone disease. Procedures employed included minimally invasive techniques shockwave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), ureterorenoscopy (URS), perurethral cystolithotripsy (PUCL), percutaneous cystolithotripsy (PCCL), and open surgery. From sociomedical records demographics, clinical history, operative procedures, complications, and outcome were recorded for all patients.

Results

Of 3969 surgeries, 2794 (70%) were minimally invasive surgery (MIS) techniques to include SWL 19%, PCNL 16%, URS 18.9%, and PUCL+PCCL 16% and 1175 (30%) were open surgeries. The main factors necessitating open surgery were large stone burden 37%, anatomical abnormalities 16%, stones with renal failure 34%, gross hydronephrosis with thin cortex 58%, urinary tract infection (UTI) 25%, and failed MIS 18%. Nearly 50% of the surgeries were necessitated by economic constraints and long distance from center where one-time treatment was preferred by the patient. Stone-free rates by open surgeries were pyelolithotomy 91%, ureterolithotomy 100%, and cystolithotomy 100% with complication rate of upto 3%.

Conclusions

In developing countries, large stone burden, neglected stones with renal failure, paucity of urological facilities, residence of poor patients away from tertiary centers necessitate open surgical procedures as the therapy of choice in about 1/3rd of the patients. Open surgery provides comparable success rates to MIS although the burden and nature of disease is more complex. The scope of open surgery will remain much wide for a large population for considered time in developing countries.

Pediatric urolithiasis: experience at a tertiary care pediatric hospital

OBJECTIVE

We aimed to determine the epidemiology, risk factors, clinical characteristics, evaluation and course of patients with urolithiasis at the Children's Hospital of Eastern Ontario to improve current diagnostic and management strategies.

METHODS

This was a retrospective study of children with newly identified urolithiasis between Jan. 1, 1999, and July 31, 2004. Cases were reviewed for demographics, presentation, family history, diagnostic methods and findings, metabolic and anatomic abnormalities, management, stone analysis and stone recurrence.

RESULTS

Seventy-two patients (40 male, 32 female; mean age 11.3 yr) were assessed. Mean follow-up was at 1.5 years. Eighteen patients (25%) had a family history of stones. Flank pain (63%) was the most common presentation. Eighty-two percent of urinalyses showed microscopic hematuria. Imaging comprised abdominal plain film radiography (56%) and (or) abdominal ultrasonography (74%). The mean stone size was 5 mm. Forty-one percent (28/69) of patients who underwent metabolic investigation had an abnormality. Fourteen percent of patients (10/72) had a genitourinary anatomical abnormality. Thirty-four patients (47%) passed their stones spontaneously, 25 patients (35%) required surgical intervention and 13 patients (18%) had yet to pass their stone. The mean size of spontaneously passed stones was 4 mm. Of 42 stones analyzed, 39 (93%) were composed of calcium oxalate or phosphate. Seventeen (24%) patients had stone recurrence during follow-up.

CONCLUSION

Pediatric patients with stones present in a manner similar to adults. Abdominal plain film radiography and ultrasonography are the preferred initial radiological investigations in children as they limit radiation exposure. Metabolic abnormalities are common and may coexist with anatomic abnormalities, therefore investigations must rule these out. One-half of patients will pass their stones spontaneously. Recurrence rates are high and long-term follow-up is recommended.

Clinical practice: surgical approaches to urolithiasis in children

The incidence of urolithiasis in children is increasing. Adequate knowledge of treatment modalities and surgical options is therefore essential for every pediatrician. Surgical approaches to urolithiasis in children continue to evolve with advancements in technology and sophistication of current equipment and techniques. Perhaps the most significant development in new techniques is the advent of robotic-assisted laparoscopy. This review, for the general pediatrician, summarizes the most recent pediatric data and guidelines for surgical approaches to treatment of urolithiasis.

The increasing pediatric stone disease problem

While once thought to be relatively rare in developed nations, the prevalence of pediatric urolithiasis appears to be increasing, and a number of factors may be contributing to this increase. Many theories are plausible and such theories include the increasing childhood obesity epidemic, a changing sex predilection, climate change, alterations in dietary habits and improving diagnostic modalities. Yet, unlike adult patients, rigorous epidemiologic studies do not exist in pediatric populations. Thus, in the setting of an increasing prevalence of childhood stone disease, improved research is critical to the development of uniform strategies for pediatric urolithiasis management.

Nutritional aspect of nephrolithiasis

Nephrolithiasis is associated with a variety of abnormalities in urinary composition. These abnormal urinary risk factors are due to dietary indiscretions, physiological-metabolic disturbances or both. Stone disease is morbid and costly, and the recurrence rates may be as high as 30-50% after 5 years. Efforts to prevent stone formation are, therefore, essential. Dietary factors play an important role in kidney stone formation. Tailored dietary recommendations based on metabolic evaluation should be offered to patients for the prevention of recurrence of stone formation. Dietary intervention and subsequent evaluations of therapeutic efficacy should be based on results from multiple 24-h urine collections. Urine flow of >1 ml/kg/h almost eliminates the risk of supersaturation for calcium oxalate, calcium phosphate and uric acid, thus protecting from the formation of corresponding kidney stones. In patients with cystenuria, the required urine flow may even be higher and, in cases such as primary xanthinuria, high fluid intake is required. Milk intake in these patients should be within the RDA of calcium and protein. In children, recommendation of a high fluid intake has only limited success. Nevertheless, each patient should be advised about adequate fluid intake to increase urine volume in accordance with body size. Although children with hypocitraturia may benefit from therapeutic agents that raise the urine citrate concentration, all children bearing residual fragments should be counseled on adequate fluid intake along with potassium citrate treatment to prevent stone regrowth or formation.

History, epidemiology and regional diversities of urolithiasis

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

Clinical and metabolic features of urolithiasis and microlithiasis in children

We evaluated the clinical, radiological and metabolic features of 162 children with urolithiasis or microlithiasis who had been referred to our pediatric nephrology clinics between 1998 and 2008 with suspected urolithiasis. The medical histories of these children (78 girls, 84 boys), who ranged in age from 2 months to 16 years (mean age 5.59 +/- 0.35 years), were reviewed retrospectively for clinical and metabolic features of urinary tract calculi. Urinary tract infections (UTI) were present in 45.9% of the cases. The most common presenting symptoms were flank pain or restlessness (25.3%) and hematuria (21.6%), followed by UTI (16%), whereas 23.5% of the cases were detected incidentally during evaluation for other medical conditions. Other symptoms at presentation included dysuria, passing stones, penile edema, enuresis, vomiting and anorexia. Urine analysis revealed metabolic abnormalities in 87% of the cases, including hypercalciuria (33.8%), hypocitraturia (33.1%), hyperoxaluria (26.5%), hyperuricosuria (25.4%), hypocitraturia + hypercalciuria (21.1%), hyperphosphaturia (20.8%) and cystinuria (5.7%). Almost 50% of the patients had a positive family history for urolithiasis. The most frequently involved site was in the kidneys (86%). Ureters and bladder were involved in 12 and 2% of the cases, respectively. A family history of urolithiasis, presenting symptoms and underlying metabolic abnormalities were similar for microlithiasis and the patients with larger stones. However, in our study population, microlithiasis was mainly a disease of young infants, with a greater chance for remission and often not associated with structural changes. The presenting symptoms of urolithiasis show a wide spectrum, so that a high index of suspicion is important for early detection. A metabolic abnormality can be identified in 87% of cases of urolithiasis. Detection of microlithiasis may explain a number of symptoms, thus reducing invasive diagnostic procedures and allowing early recognition of metabolic abnormalities. These results draw attention to the importance of screening for UTIs in patients with urolithiasis.

The clinical analysis of young children's urolithiasis due to melamine-tainted infant formula

OBJECTIVE

To analyze etiology, clinical features, effective diagnostic methods and therapeutic efficacy of infant urolithiasis related to melamine.

METHODS

A total of 2,235 children fed with milk products were screened at the Second Hospital of Shandong University between 1st September and 31st December 2008. Of the children screened, 1,242 were male and 993 female, with a median age of 15 months (range 4-72 months). Among them, 182 with detailed data were enrolled and divided into Group 1 (calculus group, n = 79) and Group 2 (noncalculus group, n = 103) according to their results of the screening. All cases were reviewed with regard to melamine exposure, presentation, laboratory data, B-ultrasound findings and treatment efficacy.

RESULTS

Compared to 103 patients without stones, the 79 patients with stones confirmed by B-ultrasound had significant differences in: melamine daily intake (5.17 ± 4.53 vs. 2.38 ± 3.39 mg/kg per day, P < 0.001) and duration of problematic milk feeding (12.53 ± 8.47 vs. 8.65 ± 3.40 months, P < 0.001). Most of the patients in Group 1 (65.82%) were asymptomatic. In Group 1, all the patients with kidney stones less than 10 mm (n = 75) were successively treated conservatively, whereas the other four with kidney stones >10 mm required surgical treatment.

CONCLUSIONS

Melamine overdose can cause an increased risk of developing kidney stones in children. B-ultrasound is the first choice for the diagnosis of urolithiasis related to melamine. For most patients, the conservative treatment is effective; however, the patients with kidney stones >10 mm, surgery may be needed.

Pediatric urolithiasis: etiology, specific pathogenesis and medical treatment

Pediatric urolithiasis is an endemic disease in certain parts of the world, namely Turkey and the Far East. As a recurrent pathology which may reveal functional as well and morphologic changes in the urinary tract, environmental factors together with urogenital abnormalities should be evaluated thoroughly in each patient. The aims of management should be complete clearance of stones, treatment of urinary tract infections, preservation of renal function and prevention of stone recurrence. In addition to certain minimally invasive stone removal procedures, treatment of pediatric urolithiasis requires a detailed metabolic evaluation in all patients on an individual basis. Obstructive pathologies have to be corrected immediately and children with a positive family history should be followed carefully with respect to a high likelihood of stone re-growth and recurrence. Although specific management of each metabolic abnormality seems to be the key factor in the medical management of stone disease, as general advice each child should be forced to adequate fluid intake which will reveal the urine volume increase in accordance with the body mass index. Moreover, medical therapeutic agents which increase urine citrate levels should be encouraged.