What do we know about pediatric renal microlithiasis?

Increased risk of nephrolithiasis: an emerging issue in children with congenital adrenal hyperplasia due to 21-hydroxylase deficiency

PURPOSE

To investigate the incidence of nephrolithiasis in a cohort of children with congenital adrenal hyperplasia (CAH), and to study if there is an association with the metabolic control of the disease.

METHODS

This study was designed as a multicenter 1 year-prospective study involving 52 subjects (35 males) with confirmed molecular diagnosis of CAH due to 21-hydroxylase deficiency (21-OHD). Each patient was evaluated at three different time-points: T0, T1 (+6 months of follow-up), T2 (+12 months of follow up). At each follow up visit, auxological data were collected, and adrenocorticotrophic hormone (ACTH), 17-hydroxyprogesterone (17-OHP), Δ4-androstenedione, dehydroepiandrosterone sulfate (DHEAS) serum levels, and urinary excretion of creatinine, calcium, oxalate and citrate were assayed. Moreover, a renal ultrasound was performed.

RESULTS

The incidence of nephrolithiasis, assessed by ultrasound was 17.3% at T0, 13.5% at T1 and 11.5% at T2. At T0, one subject showed nephrocalcinosis. In the study population, a statistically significant difference was found for 17-OHP [T0: 11.1 (3.0-25.1) ng/mL; T1: 7.1 (1.8-19.9) ng/mL; T2: 5.9 (2.0-20.0) ng/mL, p < 0.005], and Δ4-androstenedione [T0: 0.9 (0.3-2.5) ng/mL; T1: 0.3 (0.3-1.1) ng/mL; T2: 0.5 (0.3-1.5) ng/mL, p < 0.005] which both decreased over the follow up time. No statistically significant difference among metabolic markers was found in the group of the subjects with nephrolithiasis, even if 17-OHP, DHEAS and Δ4-androstenedione levels showed a tendency towards a reduction from T0 to T2. Principal component analysis (PCA) was performed to study possible hidden patterns of associations/correlations between variables, and to assess the trend of them during the time. PCA revealed a decrease in the amount of the variables 17-OHP, Δ4-androstenedione, and ACTH that occurred during follow-up, which was also observed in subjects showing nephrolithiasis.

CONCLUSIONS

our data demonstrated that children affected with 21-OHD can be at risk of developing nephrolithiasis. Additional studies are needed to clarify the pathogenesis and other possible risk factors for this condition, and to establish if regular screening of kidney ultrasound in these patients can be indicated.

The Efficacy of Guy's Stone Score for Predicting the Stone-Free and Complication Rates in Children Treated by Percutaneous Nephrolithotomy

Introduction: To determine the efficacy of Guy's stone score (GSS) for predicting stone-free and complication rates after percutaneous nephrolithotomy (PCNL) in children. Patients and Methods: A total of 197 renal units (RUs) in 173 children (≤17 years) who referred to our clinic were included in our study. RUs with stones were classified as four groups according to GSS. The results were designated as stone free or as having residual stones. Complications were evaluated according to GSS, the Satava, and modified Clavien grading system. All parameters were evaluated by using univariate and multivariate analysis. Results: The median age of patients was 6 years (1-17 years). Stone-free status was 77% and complication rate was 17%. Stone-free rate was established 89% for group 1, 78% for group 2, 75% for group 3, and 57% for group 4. There was a positive association between GSS and stone-free status (p = 0.02). No relationship was found between GSS and the complication rate (p = 0.42). In multivariate analysis, GSS was the only independent factor for predicting stone-free status. Conclusion: Current study revealed that GSS has a predictive ability for stone-free status; however, GSS is insufficient for predicting complications after pediatric PCNL. Even though, GSS does not fully reflect the characteristics of the pediatric population, we believe that it might provide useful insights for clinicians when recommending and discussing treatment options for children with urolithiasis.

Does Previous Open Stone Surgery Affect the Outcome of Shock Wave Lithotripsy Treatment in Children?

INTRODUCTION

The aim of the study was to evaluate the efficiency of shock wave lithotripsy (SWL) in children who previously underwent ipsilateral open renal stone surgery (ORSS).

METHODS

A total of 315 renal units (RUs) with renal stones underwent SWL treatment in our department over a period of 18 years. A total of 274 RUs (87%) with no history of ORSS were categorized as group 1 and 41 RUs (13%) with a history of ORSS were categorized as group 2. The characteristics of the patients and renal stones, as well as the treatment modalities, were reviewed retrospectively, and the results were compared in terms of the rates of stone-free patients and complications.

RESULTS

The stone-free rates were statistically lower in patients with an existing history of ORSS (p = 0.002), especially for stones located at the lower calyx (p = 0.006). However, there were no differences between groups in the rate of complications (p = 0.75). History of ipsilateral ORSS, age, and stone burden were independent risk factors that predicted a stone-free status in the regression analysis (p = 0.016, p = 0.045, and p = 0.001, respectively).

CONCLUSION

The overall stone-free rate after SWL was found to be significantly lower in children with a history of ORSS than in those without, and this finding was significantly prominent for lower calyx stones. In spite of the possible difficulties in achieving surgical access due to anatomical changes in retrograde intrarenal surgery or mini-/micro-percutaneous nephrolithotomy, we believe that these techniques might be good alternatives for SWL in future cases.