Urinary calcium and uric acid excretion in children with vesicoureteral reflux

Bladder Stones in Renal Transplant Patients: Presentation, Management, and Follow-up

INTRODUCTION

The study aim was to analyze the presentation, management, and follow-up of renal transplant patients developing bladder calculi.

METHODS

Patients who underwent renal transplant with postoperative follow-up at our institution were retrospectively analyzed (1984-2023) to assess for the development of posttransplant bladder stones. All bladder stones were identified by computerized tomography imaging and stone size was measured using this imaging modality.

RESULTS

The prevalence of bladder calculi post-renal transplantation during the study window was 0.22% (N = 20/8,835) with a median time to bladder stone diagnosis of 13 years posttransplant. Of all bladder stone patients, 6 (30%) received deceased donor and 14 (70%) living donor transplants. There were 11 patients with known bladder stone composition available; the most common being calcium oxalate (N = 6). Eleven (55%) patients had clinical signs or symptoms (most commonly microhematuria). Fourteen of the bladder stone cohort patients (70%) underwent treatment including cystolitholapaxy in 12 subjects. Of these 14 patients, 9 (64%) were found to have nonabsorbable suture used for their ureteroneocystostomy closure.

CONCLUSIONS

The prevalence of bladder stones post-renal transplant is low. The utilization of nonabsorbable suture for ureteral implantation was the main risk factor identified in our series. This technique is no longer used at our institution. Other factors contributing to bladder stone formation in this population warrant identification.

Evaluation of renal function and scars in children with primary vesicoureteral reflux

OBJECTIVE

To evaluate growth, glomerular and tubular function, renal damage, scars in children affected by primary VUR.

METHOD

We retrospectively evaluated the clinical records of our Unit from January 2006 to September 2020. For each patient we evaluated growth, laboratoristic and scintigraphic glomerular and tubular function, renal damage and collective system urodynamics at baseline and at the last visit.

RESULT

We enrolled 41 patients affected by primary VUR and treated with continuous antibiotic prophylaxis. Glomerular function and urodynamics did not change over time. EFNa directly correlated with weight (r 0.44 p 0.004) and TRP inversely correlated with severity of reflux (r -0.32, p 0.04). Female sex was associated to nephrolithiasis (OR 17.0, p 0.02) and proteinuria (at T0 OR 5.8 p 0.03 at T1 OR 5.8, p 0.03). Daily proteinuria increased with age (r 0.66, p <0.0001 at T0 and r 0.44 p 0.004 at T1) while protein-to-creatinine ratio decreased. Renal scars at T0 inversely correlated with glomerular and tubular function at T1 but they did not correlate with severity or laterality of reflux.

CONCLUSION

Even if renal function remains stable through years, it is critical to identify the subjects with significant congenital renal damage.

An Important Risk Factor Affecting Hypercalciuria in Children: Vesicoureteral Reflux

INTRODUCTION

 A large number of genes and environmental factors, like dietary habits, play a role in the development of hypercalciuria in children. In this study, we aimed to determine the effects of the presence and grade of vesicoureteral reflux (VUR) on hypercalciuria status in children.

MATERIALS AND METHODS

 Data for 165 patients who admitted to the Pediatric Urology Department were retrospectively analyzed. The patients were composed of following four different groups: (1) urinary stone patients, (2) VUR patients under follow-up, (3) corrected VUR patients, and (4) control. The demographic features, clinical data, and laboratory tests for the groups were compared.

RESULTS

 The mean age of the patients was 100.6 ± 54.69 months and the female/male ratio was 79:86. The mean urinary calcium/creatinine (UCa/Cr) excretion and the frequency of high UCa/Cr ratios in the corrected VUR group were similar to those in the control group (p = 0.375 and 0.965, respectively). In contrast, the mean UCa/Cr excretion and frequency of high UCa/Cr ratios in the urinary stone and follow-up VUR groups were significantly higher than those in the corrected VUR group (p < 0.001, < 0.001, 0.003, and 0.029, respectively). The mean UCa/Cr excretion and frequency of high UCa/Cr ratios in the follow-up VUR group were similar to those in the urinary stone group (p = 0.323 and 0.425, respectively). In the follow-up VUR group, although reflux laterality had no effect on the UCa/Cr ratios (p = 0.180 and 0.108, respectively), the mean and frequency of high UCa/Cr ratios were higher in high-grade reflux cases (p < 0.001 and p = 0.042, respectively).

CONCLUSION

 Both the mean UCa/Cr ratio and the rate of hypercalciuria in the corrected reflux group were significantly lower than the corresponding values in the follow-up VUR and urinary stone groups. Further, the follow-up VUR patients had similar urinary calcium excretion levels as the stone patients. VUR treatment is associated with a decrease in urinary calcium excretion to the normal population level. A positive correlation between reflux degree and calcium excretion was observed.

Prevalence of Vesicoureteral Reflux and Urinary Tract Infection in Children with and without Urolithiasis

Background: Vesicourethral reflux (VUR) is a common urinary tract disorder in children, which may be associated with urolithiasis. Objectives: The current study aimed to investigate vesicoureteral reflux in children with and without urolithiasis. Methods: In this case-control study, 130 children younger than 10 years, with a confirmed diagnosis of urinary tract infection (UTI) are investigated. The demographic information and clinical status of all participants were recorded. Ultrasonography was performed for all children, and they were divided into two groups of 65 subjects based on the results: group 1, children with UTI+stone; and group 2, children with UTI+ non-stone. All children received Voiding Cystourethrogram to evaluate Vesicourethral reflux. Results: The mean age of participants was 7.48 ± 3.2 years, and 68 (52.7%) of them were male. Also, VUR was observed in 33 (25.38%) cases. The frequency of reflux in the UTI + stone group was 21 (32.3%), which was significantly higher than the other group (12 cases, or 18.46%) (P = 0.011). However, the association between UTI and stone (P = 0.3, CC = -0.01) was not significant. Conclusions: This study demonstrated a significant correlation between urinary tract stones and VUR in children with urinary tract infections. It is recommended to investigate the presence of stone or VUR in children suffering from any of the described disorders.

The pelvis urinary microbiome in patients with kidney stones and clinical associations

BACKGROUND

The long-held notion that, without urinary tract or circulatory infection, bladder urine and blood are sterile biofluids has been disproven. There have been no previous reports on the kidney pelvis urinary microbiome after bladder disinfection in kidney stone patients. This study aimed to determine whether a kidney pelvis urinary microbiome is present after eliminating the influence of the bladder urinary microbiome, whether the microbiome composition is different in patients with stone kidney pelvis (SKP) and non-stone kidney pelvis (NSKP), and the correlation between SKP and patient clinical characteristics.

RESULTS

Comparisons of bacterial diversity and community structure exhibited that urine in bladder was similar to SKP and NSKP. However, the comparisons showed that urine samples were different from blood. The most common operational taxonomic units were shared by all three types of urine samples. Corynebacterium was significantly higher in SKP compared to NSKP. Several bacteria were associated with patient characteristics, including Lactobacillus, which was positively correlated with fasting blood glucose, and Prevotella was negatively correlated with BMI. Lactobacillus was significantly higher in SKP compared to blood but not in NSKP compared to blood.

CONCLUSIONS

The composition of the kidney pelvis urinary microbiome after disinfection of the bladder and its similarity to the bladder microbiome indicate that bladder urine can be used to replace kidney pelvis urine in microbiome research. Additionally, the comparison of SKP and NSKP and clinical associations suggest that the occurrence of kidney stones is responsible for the SKP urinary microbiome.

[Unilateral renal agenesis. New arguments about the genetic relationship between kidney malformations and urolithiasis]

BACKGROUND

In few previous works, it has been reported that hypercalciuria is associated with some types of CAKUT, namely ureteropelvic junction obstruction, vesicoureteral reflux or simple renal cysts. In addition, one higher prevalence of hypercalciuria and/or urolithiasis has been described in their family members compared to the general population. This study was carried out to find out whether children with unilateral renal agenesis (URA) have these features previously described in other CAKUT types.

METHODS

In a descriptive and multicenter study we studied the prevalence of hypercalciuria, hypocitraturia and urolithiasis in 67 children (43 males and 24 females) with URA and their families.

RESULTS

The two metabolic anomalies that promote stone formation were observed in 26 children (38.8%), distributed as follows: hypercalciuria in 16, hypocitraturia in 9, and both hypercalciuria and hypocitraturia in 1. Eight children (11.9%) suffered renal colic during follow-up. Familial history of urolithiasis was found in 42/67 children (62.7%): in 12 of the first-degree relatives, in 15 of the second degree relatives and in 15 patients both in the first-degree as in their second degree relatives. In contrast, in historic control group, only in 28.1% of families at least one member had urolithiasis.

CONCLUSION

Our results show that the prevalence of hypercalciuria and/or hypocitraturia is greater in pediatric patients with URA than in the general population. Likewise, the prevalence of urolithiasis in the families of these children is also higher than that in the general population.

The association of hypercalciuria and hyperuricosuria with vesicoureteral reflux in children

OBJECTIVES

One of the important complications of vesicoureteral reflux (VUR) is the development of urolithiasis. Identifying factors involved in development of urolithiasis in children with VUR is immensely important. This study was conducted to determine the association between hypercalciuria and hyperuricosuria with VUR in children.

METHODS

One-hundred children with VUR (case group) were compared to 100 healthy children (control group) in terms of hypercalciuria and hyperuricosuria. To measure these markers, random morning fasting urine samples were used. Data were analyzed using statistical tests.

RESULTS

Hypercalciuria and hyperuricosuria frequencies, and also urine calcium/creatinine (Ca/Cr) and urine uric acid/creatinine (UA/Cr) ratios were significantly higher in the case group compared to the control group (P < 0.05). A significant difference was found between hypercalciuria and hyperuricosuria in severity of VUR (P < 0.05). A positive correlation was observed between hypercalciuria and hyperuricosuria and severity of VUR (P < 0.05).

CONCLUSIONS

The present study showed that there is association between hypercalciuria, hyperuricosuria and VUR in children. It is recommended to adopt measures to prevent the development of urolithiasis in VUR patients.

A unique presentation, and management, of acute urinary retention in a young boy with underlying vesicoureteral reflux

Vesicoureteral reflux (VUR) affects ∼1% of children. We present an unusual case of urinary retention secondary to an obstructing urethral stone, underlying reflux, and its management. A 7-year-old boy presenting with acute urinary retention had a palpable penile shaft swelling and patent urethral meatus on examination. Cysto-urethroscopy with a 6.6Fr ureteroscope, due to unavailability of paediatric instruments, revealed an obstructing calculus impacted in the navicular fossa. This was laser fragmented and extracted. Cystoscopy revealed multiple bladder calculi with a patulous right ureteric orifice. Post-operative investigations revealed a small, scarred right kidney (ultrasound), bilateral ureteric reflux (micturating-cystourethrogram), 4 cm by 0.8 cm right ureteric calculus (CT-KUB) and 4% right split renal function (DMSA). Right laparoscopic nephroureterectomy was subsequently performed. Our case highlights the variety with which VUR can present and the effectiveness of a ureteroscope in an emergency setting as an alternative to a paediatric cystoscope to visualize the urethra and the bladder.

Unilateral hypercalciuria: a stealth culprit in recurrent ipsilateral urolithiasis in children

PURPOSE

Hypercalciuria is a risk factor for nephrolithiasis. We hypothesized that children with recurrent stones in 1 but not both kidneys and a normal 24-hour bladder urine calcium-to-creatinine ratio might exhibit isolated hypercalciuria of the affected kidney.

MATERIALS AND METHODS

Patients 18 years or younger with symptomatic urolithiasis who had undergone ureteroscopic stone removal were included. All subjects underwent 24-hour bladder urinalysis. Subjects with an increased urine calcium-to-creatinine ratio from the 24-hour urine collection were excluded. The 4 subject cohorts defined were 1) single stone episode in 1 kidney, 2) single stone episode in both kidneys, 3) recurrent stone episodes on 1 side and 4) recurrent stone episodes on both sides. All urine collections were obtained at ureteroscopy. Urine was obtained from the bladder and from the renal pelvis of the kidney forming the stone. Spot urine calcium-to-creatinine ratio was determined from these samples.

RESULTS

A total of 329 patients were included. Nine of 74 subjects (12%) with recurrent stone episodes on 1 side had increased spot urine calcium-to-creatinine ratio from the affected kidney. No patients in the other cohorts had increased spot urine calcium-to-creatinine ratio. Patients who formed recurrent stones in 1 kidney had increased spot urine calcium-to-creatinine ratio in the affected kidney vs other stone formers (ANOVA p <0.001).

CONCLUSIONS

Unilateral hypercalciuria can occur in children with normal calcium levels in bladder urine. Unilateral hypercalciuria should be considered as a risk factor for nephrolithiasis in children with recurrent stone episodes in 1 kidney only.