Changing stone composition profile of children with nephrolithiasis

A Precision Medicine Approach Uncovers a Unique Signature of Neutrophils in Patients With Brushite Kidney Stones

Introduction

We have previously found that papillary histopathology differs greatly between calcium oxalate and brushite stone formers (SF); the latter have much more papillary mineral deposition, tubular cell injury, and tissue fibrosis.

Methods

In this study, we applied unbiased orthogonal omics approaches on biopsied renal papillae and extracted stones from patients with brushite or calcium oxalate (CaOx) stones. Our goal was to discover stone type-specific molecular signatures to advance our understanding of the underlying pathogenesis.

Results

Brushite SF did not differ from CaOx SF with respect to metabolic risk factors for stones but did exhibit increased tubule plugging in their papillae. Brushite SF had upregulation of inflammatory pathways in papillary tissue and increased neutrophil markers in stone matrix compared with those with CaOx stones. Large-scale 3-dimensional tissue cytometry on renal papillary biopsies showed an increase in the number and density of neutrophils in the papillae of patients with brushite versus CaOx, thereby linking the observed inflammatory signatures to the neutrophils in the tissue. To explain how neutrophil proteins appear in the stone matrix, we measured neutrophil extracellular trap (NET) formation—NETosis—and found it significantly increased in the papillae of patients with brushite stones compared with CaOx stones.

Conclusion

We show that increased neutrophil infiltration and NETosis is an unrecognized factor that differentiates brushite and CaOx SF and may explain the markedly increased scarring and inflammation seen in the papillae of patients with brushite stones. Given the increasing prevalence of brushite stones, the role of neutrophil activation in brushite stone formation requires further study.

Extracorporeal Shockwave Lithotripsy Versus Flexible Ureteroscopy for the Management of Upper Tract Urinary Stones in Children

OBJECTIVE

To compare the efficacy and morbidity of extracorporeal shockwave lithotripsy (SWL) and flexible ureteroscopy (F-URS) for the management of upper tract urinary stones in children.

METHODS

All SWL and F-URS performed in children in a single institution between 2000 and 2014 were reviewed retrospectively. Only procedures performed to treat upper tract urinary stones (upper ureter or kidney) were included in this study. Preoperative and perioperative outcomes were compared between the SWL and F-URS groups. Univariate and multivariate logistic regression analyses were used to evaluate predictors of stone-free (SF) status.

RESULTS

Over the study period, 100 SWL and 46 F-URS were conducted in 69 children. The SWL and F-URS groups were comparable in terms of stone size (14.6 vs 13.2 mm, p = 0.32), but there were more multiple stones (31% vs 57%; p = 0.003) and lower pole calculi (14% vs 37%; p = 0.003) in the F-URS group. The SF rate after one procedure was almost two times higher in the F-URS group compared with the SWL group (37% vs 21%; p = 0.04) without increasing the complication rate (21.7% vs 16%; p = 0.31). Similar results were observed in the subgroup of single renal stones <20 mm (SF rates: 78.6% vs 50%; p = 0.06). In multivariate analysis, the use of F-URS vs SWL was a predictor of an SF status (odds ratio = 3.7; p = 0.02).

CONCLUSION

F-URS provides a higher single-session SF rate, despite more complex urinary stones (multiple, lower pole, etc.) and without increasing morbidity.

Efficacy and safety of percutaneous nephrolithotomy with adult standard size instruments in children under 3 years of age: a 10 years single-center experience

BACKGROUND

Using percutaneous nephrolitotomy (PCNL) with large adult instruments in treatment of pediatricurolithiasis is still in debate. This study was conducted to evaluate the efficacy and safety of PCNL with adult's instrument in treatment of patients less than 3 years old.

METHODS

Data on patient characteristics and outcomes for 261 consecutive children undergoing PCNL at a Labbafinejad University Hospital were collected prospectively from September 2006 to February 2016. Thirty-two children, with 34 renal units, who were treated with PCNL were enrolled in the study. All PCNL procedures were performed via subcostal approach with one access tract in all of them. Postoperative complications were evaluated according to the modified Clavien grading system.

RESULTS

The mean age of patients was 19.4 ± 6.2 months. Two patients had bilateral stones; thus, PCNL was performed on 34 kidney units. The mean size of the largest stone diameter was 17.5 ± 7.8 mm. The mean duration of procedures was 121.52 ± 29.05 minutes, ranging from 60 to 180 minutes. The most common complication was fever (n = 9, 26.4%), and hemorrhage that needs transfusion was the second one (n = 4, 11.7%). Seventeen patients with complications were in the first degree of Clavien complication system and five of them were in the second degree.

CONCLUSIONS

Due to our experience, utilizing PCNL with adult-sized instruments in management of urolithiasis in less than 3 years old children appeared to be effective and relatively safe.

A comparison of outcomes after percutaneous nephrolithotomy in children and adults: a matched cohort study

INTRODUCTION

Percutaneous nephrolithotomy (PCNL) has surpassed open stone surgery as the operation of choice for large and complex stone burdens (figure). Although the procedure was developed in adults, its principles have been extrapolated to children. There is a paucity of literature comparing outcomes of PCNL in adults and children for similar stone burdens.

OBJECTIVE

The purpose of this study was to evaluate outcomes following PCNL among children and adults with similar stone burdens.

PATIENTS AND METHODS

Data on patient characteristics and outcomes for 2196 consecutive patients undergoing PCNL at a single institution were collected prospectively from January 1992 to July 2013. Thirty-one pediatric patients undergoing 39 PCNLs were identified. Each pediatric PCNL was matched in a ratio of 1:4 to adult PCNLs by year of surgery and stone burden characteristics (staghorn, partial staghorn, number of stones). All PCNLs were performed by two fellowship-trained endourologists who operate on both adult and pediatric patients. Ultrasonic lithotripsy was used primarily. The primary outcome measure was stone-free rate (SFR) at hospital discharge. Secondary outcomes included the need for second-look nephroscopy, length of hospital stay, complication rate, and blood transfusion rate. The Student t test was used for continuous variables and the Fisher exact for categorical variables.

RESULTS

The median age for the pediatric group was 13.9 ± 4.30 years and for the adult group was 55.4 ± 15.1 years. Pediatric patients tended to present with metabolic stones, with no difference in rates of infection stones. No difference was found in SFR at time of hospital discharge (86.1% vs. 86.4%, p = 0.2). More pediatric patients required a second access tract than adult patients (15.4% vs. 4.52%, p = 0.02). There was no significant difference in the need for second-look nephroscopy, length of stay, or complication rates (overall and by Clavien classification subgroup) between both groups. The rates of blood transfusion were low in both groups (0% vs. 0.6%, p = 0.80).

DISCUSSION

There was no difference in primary and secondary outcomes among children compared with adults undergoing PCNL in our study. The outcomes reported in this study were similar to published literature. A limitation of this study is the low number of pediatric patients. However, it is unique to have a single-center study that compares PCNL outcomes in both adult and pediatric patient and accounts for stone burden characteristics.

CONCLUSIONS

Although principles of PCNL were developed in adults, this study affirms the safety and efficacy of PCNL in both pediatric and adult patients.

Arguments for choosing extracorporeal shockwave lithotripsy for removal of urinary tract stones

At a time when there is an almost unlimited enthusiasm and preference among urologists for endoscopic stone removal, we have found it essential to meet some of the frequently presented arguments on why extracorporeal shockwave lithotripsy (SWL) should not be used. We have based our considerations in this brief article on our 30-35 years' experience with the non-invasive or least invasive technique that SWL represents. Stone disintegration, requirement of repeated treatment sessions, the concern of residual fragments, complications and economic aspects are some points that are discussed.