Urolithiasis Through the Ages: Data on More Than 200,000 Urinary Stone Analyses

Antiurolithiatic effects of Cassia fistula Lin. fruit extracts on ethylene glycol-induced nephrolithiasis in rats

Urinary stones are a growing disease that results from pathological biomineralization. Cassia fistula Lin. is traditionally used to treat urinary stones. However, no scientific evidence is available to prove its antilithiatic effect. This study evaluates the antilithiatic potential of aqueous and ethanolic extract of Cassia fistula Lin. fruit (Cff) against calcium oxalate kidney stones. Forty-two male Wistar rats were divided into seven groups (n = 6/group): Group I (control), Group II (rats treated with ethylene glycol and ammonium chloride developed nephrolithiasis after 28 days), Group III (lithiatic rats receiving distilled water for 30 days), Group IV and V (lithiatic rats receiving aqueous extract of Cff at doses of 1 and 100 mg/kg body weight for 30 days, respectively) and Group VI and VII (lithiatic rats receiving ethanolic extract of Cff at doses of 1 and 100 mg/kg body weight for 30 days, respectively). Some parameters of urine and serum, and also renal oxidative stress and histopathology were used to determine the antilithiatic effect of aqueous and ethanolic extract of Cff. Therefore, the types of extracts of Cff improved abnormal levels of urine, serum, and renal oxidative stress and histopathology parameters. This antilithiatic effect of aqueous and ethanolic extracts of Cff, can be attributed to the anti-crystallization and antioxidant properties of the extracts and the ability to improve urine and serum biochemistry. RESEARCH HIGHLIGHTS: Ethylene glycol and ammonium chloride-induced urolithiasis, aggregation of calcium oxalate deposits, increase of some urinary and serum parameters, relative kidney weight, kidney size and MDA activity, decrease of some urinary parameters, relative body weight and SOD activity. Aqueous and ethanolic extracts of Cassia fistula Lin. lead to the treatment of urolithic rats by decreasing levels of urinary oxalate, phosphate, urea, serum urea, uric acid, creatinine, calcium, phosphate, MDA, kidney weight and kidney size, increasing levels of urinary calcium, creatinine, magnesium, citrate, body weight and SOD activity in the kidney, eliminating CaOx deposition (esp. ethanolic extract).

Utility of the modified 5-item frailty index as a predictor of postoperative febrile urinary tract infection in patients who underwent ureteroscopy with laser lithotripsy

PURPOSE

This study aimed to assess the effect of the modified 5-item frailty index on perioperative complications and surgical outcomes in patients who underwent ureteroscopy with laser lithotripsy for upper urinary tract stones.

METHODS

Patients who underwent ureteroscopy with laser lithotripsy for upper urinary tract stones between 2019 and 2022 were reviewed retrospectively. Assessment was performed using the modified 5-item frailty index based on medical history (hypertension, diabetes, heart failure, chronic obstructive pulmonary disease) and functional status. Patients were categorized into the high (≥ 2) and low (≤ 1) modified 5-item frailty index groups based on the frailty score. We compared the perioperative complications and surgical outcomes between the two groups.

RESULTS

Seventy-one (15.8%) and 393 (84.1%) of the 467 patients were classified into the high and low modified 5-item frailty index groups, respectively. The high modified 5-item frailty index group exhibited a significant association with increased febrile urinary tract infections compared to the low modified 5-item frailty index group [≥ 37.8 °C: 15 (20.3%) vs 13 (3.3%), p < 0.001; ≥ 38 °C: 9 (12.2%) vs 7 (1.8%), p < 0.001]. Surgical outcomes, including operative time and stone-free rate, did not differ significantly between the two groups.

CONCLUSION

The modified 5-item frailty index is valuable for predicting postoperative complications, particularly febrile urinary tract infections, after ureteroscopy with laser lithotripsy for upper urinary tract stones. This index allows for practical preoperative risk assessment in patients who underwent ureteroscopy with laser lithotripsy.

Exploring the association between multiple factors and urolithiasis: A retrospective study and Mendelian randomization analysis

To investigate the relationship between several factors and urinary stone as well as different stone compositions. To guide the diagnosis, treatment, and prevention of urinary stone recurrence. We used bidirectional Mendelian randomization to analyze the causal relationship between hypertension and urinary stones, diabetes and urinary stones, and body mass index (BMI) and urinary stones. We retrospectively analyzed the medical records of patients with urinary stones admitted to a tertiary care hospital in Chongqing, China, from July 2015 to October 2022. Patients were included when they were first diagnosed with urinary stones. The odds ratio of calculi on hypertension estimated by inverse variance weighted was 8.46 (95%CI: 4.00-17.90, P = 2.25 × 10-8). The stone composition analysis showed that there were 3101 (67.02%) mixed, 1322 (28.57%) calcium oxalate monohydrate, 148 (3.20%) anhydrous uric acid, 16 (0.35%) magnesium ammonium phosphate hexahydrate, 11 (0.24%) dicalcium phosphate dihydrate, 10 (0.22%) carbonate apatite, 8 (0.17%) L-cystine, 4 ammonium uric acid (0.09%), and 7 other stone types (0.15%). Mendelian randomization studies have proven that urinary stones may be a potential risk factor for hypertension, while there is no causal relationship between diabetes and stones, BMI, and stones. Our retrospective study has shown that urinary stone components are closely associated with sex, age, hypertension, diabetes, and BMI. It is reasonable to suspect that treating a single stone component is ineffective in preventing recurrence. We also found that the peak incidence of urinary stones was at the most active stage of most people's working lives.

Medical management of urolithiasis: Great efforts and limited progress

Objective

To provide a comprehensive review on the existing literature on medical management of urolithiasis.

Methods

A thorough literature review was performed using Medline, PubMed/PMC, Embase, and the Cochrane Database of Systematic Reviews up to December 2022 to identify publications on the medical management of urolithiasis. Studies that assessed dietary and pharmacologic management of urolithiasis were reviewed; studies on medical expulsive therapy were not included in this review.

Results

Medical management of urolithiasis ranges from the prophylactic management of kidney stone disease to dissolution therapies. While most treatment concepts have been long established, large randomized controlled trials are scarce. Dietary modification and increased fluid intake remain cornerstones in the conservative management of urolithiasis. A major limitation for medical management of urolithiasis is poor patient compliance.

Conclusion

Medical management of urolithiasis is more important in patients with recurrent urolithiasis and patients with metabolic abnormalities putting them at higher risk of developing stones. Although medical management can be effective in limiting stone recurrence, medical interventions often fail due to poor compliance.

Understanding formation processes of calcareous nephrolithiasis in renal interstitium and tubule lumen

Kidney stone, one of the oldest known diseases, has plagued humans for centuries, consistently imposing a heavy burden on patients and healthcare systems worldwide due to their high incidence and recurrence rates. Advancements in endoscopy, imaging, genetics, molecular biology and bioinformatics have led to a deeper and more comprehensive understanding of the mechanism behind nephrolithiasis. Kidney stone formation is a complex, multi-step and long-term process involving the transformation of stone-forming salts from free ions into asymptomatic or symptomatic stones influenced by physical, chemical and biological factors. Among the various types of kidney stones observed in clinical practice, calcareous nephrolithiasis is currently the most common and exhibits the most intricate formation mechanism. Extensive research suggests that calcareous nephrolithiasis primarily originates from interstitial subepithelial calcified plaques and/or calcified blockages in the openings of collecting ducts. These calcified plaques and blockages eventually come into contact with urine in the renal pelvis, serving as a nidus for crystal formation and subsequent stone growth. Both pathways of stone formation share similar mechanisms, such as the drive of abnormal urine composition, involvement of oxidative stress and inflammation, and an imbalance of stone inhibitors and promoters. However, they also possess unique characteristics. Hence, this review aims to provide detailed description and present recent discoveries regarding the formation processes of calcareous nephrolithiasis from two distinct birthplaces: renal interstitium and tubule lumen.

Harnessing Artificial Intelligence for Enhanced Renal Analysis: Automated Detection of Hydronephrosis and Precise Kidney Segmentation

Background and objective

Hydronephrosis is essential in the diagnosis of renal colic. We automated the detection of hydronephrosis from ultrasound images to standardize the therapy and reduce the misdiagnosis of renal colic.

Methods

Anonymously collected ultrasound images of human kidneys, both normal and hydronephrotic, were preprocessed for neural networks. Six "state of the art" models were trained and cross-validated for the detection of hydronephrosis, and two convolutional networks were used for kidney segmentation. In the testing phase, performance metrics included true positives, true negatives, false positives, false negatives, accuracy, and F1 score, while the evaluation of the segmentation task involved accuracy, precision, dice, jaccard, recall, and ASSD.

Key findings and limitations

A total of 523 sonographic kidney images (423 nonhydronephrotic and 100 hydronephrotic) were collected from three different ultrasound devices. After training on this dataset, all models were used to evaluate 200 new ultrasound kidney images (142 nonhydronephrotic and 58 hydronephrotic kidneys). The highest validation accuracy (98.5%) was achieved by the AlexNet model (GoogLeNet 97%, AlexNet_v2 96%, ResNet50 96%, ResNet101 97.5%, and ResNet152 95%). The deeplabv3_resnet50 and deeplabv3_resnet101 reached a dice coefficient of 94.74% and 94.48%, respectively, on the task of automated kidney segmentation. The study is limited by analyzing only hydronephrosis, but this specific focus enabled high detection accuracy.

Conclusions and clinical implications

We show that our automated ultrasound deep learning model can be trained and used to interpret and segmentate ultrasound images from different sources with high accuracy. This method will serve as an automated tool in the diagnostic algorithm of acute renal failure in the future.

Patient summary

Hydronephrosis is crucial in the diagnosis of renal colic. Recent advances in artificial intelligence allow automated detection of hydronephrosis in ultrasound images with high accuracy. These methods will help standardize the diagnosis and treatment renal colic.

Composition analysis of renal and ureteral calculi in a single center in northern China in the past decade

The current report aimed to evaluate the characteristics of stone composition in 3637 renal and ureteral calculi patients in a single center while clarifying its relationship with sex, age, and time. Out of 3637 cases of upper urinary tract stones, stone specimens were analyzed retrospectively. There were 2373 male patients aged 6 months-87 years, with an average age of 44.73 ± 15.63 years, and 1264 female patients aged 4 months-87 years, with an average age of 46.84 ± 16.00 years. The male-female ratio was 1.88:1. Five hundred twelve patients had ureteral calculi, and 3125 had renal calculi. The SPSS software helped analyze the relationship between renal and ureteral calculi composition and sex, age, and time. Stone composition demonstrated 2205 cases of calcium oxalate stones (60.6%), 518 carbonate apatite (14.2%), 386 uric acids (10.6%), 232 magnesium ammonium phosphate (6.4%), 117 calcium phosphate (3.2%), 76 cystine (2.1%), 47 sodium urate (1.3%), 31 others (0.9%), and 25 ammonium urate (0.7%) cases. The overall male-to-female sex ratio was 1.88:1. Stones in the upper urinary tract were significantly more frequent in men than in women between the ages of 31 and 60. However, such stones were significantly more frequent in women than men over 80 (P < .05). Cystine, Sodium urate, Carbonated apatite, and uric acid indicated significant differences between different age categories (all P < .001). Stone composition analyses revealed that the frequency of calcium oxalate calculi has increased annually, while cystine and carbonated apatite incidences have dropped annually over the past decade. The components of renal and ureteral calculi vary significantly based on age and sex, with calcium oxalate calculi being more frequent in men while magnesium ammonium phosphate stones are more frequent in female patients. The age between 31 and 60 years is the most prevalent for renal and ureteral calculi in men and women.

Establishment and application of a nomogram diagram for predicting calcium oxalate stones in patients with urinary tract stones

This retrospective study aims to examine the correlation between calcium oxalate (CaOx) stones and common clinical tests, as well as urine ionic composition. Additionally, we aim to develop and implement a personalized model to assess the accuracy and feasibility of using charts to predict calcium oxalate stones in patients with urinary tract stones. A retrospective analysis was conducted on data from 960 patients who underwent surgery for urinary stones at the First Affiliated Hospital of Soochow University from January 1, 2010, to December 31, 2022. Among these patients, 447 were selected for further analysis based on screening criteria. Multivariate logistic regression analysis was then performed to identify the best predictive features for calcium oxalate stones from the clinical data of the selected patients. A prediction model was developed using these features and presented in the form of a nomogram graph. The performance of the prediction model was assessed using the C-index, calibration curve, and decision curve, which evaluated its discriminative power, calibration, and clinical utility, respectively. The nomogram diagram prediction model developed in this study is effective in predicting calcium oxalate stones which is helpful in screening and early identification of high-risk patients with calcium oxalate urinary tract stones, and may be a guide for urologists in making clinical treatment decisions.

Computed tomographic characterization of urinary stones in patients with urolithiasis from Southeast Mexico

Urolithiasis (UL) is a severe public health concern in southeastern Mexico. Computed tomography (CT) is the first-line diagnostic method for patients with suspected UL. The present study aimed to characterize stones in the entire urinary system using CT and to contribute to personalized treatment in patients with UL. Patients >18 years of age with suspected UL were enrolled. Characteristics of UL included stone size, location (kidney, ureters, and bladder), composition of the stone in Hounsfield units (HU), presence of staghorn stone(s), and obstructive uropathy. Patients were stratified according to sex and age to determine whether stone size and HU were dependent on hormonal factors in females and on prostatic hyperplasia in males. The Mann-Whitney U test was used to compare median values. Frequencies are expressed as percentages and were analyzed using the Mantel-Haenszel chi-squared test. A total of 1150 patients were included in this study, of whom 744 (64.7 %) had UL in only 1 anatomical location in the urinary system, and 406 (35.3 %) had stones in ≥2 anatomical locations. Localization and stone size differed between males and females (p < 0.05). Additionally, males exhibited differences in HU (p = 0.024) and frequency of obstructive uropathy (p = 0.10) when stratified according to age (≤50 and > 50 years). In addition, females exhibited statistical differences in HU (p = 0.010) and kidney stone size (p = 0.047) dependent on age (≤47 and > 47 years). In conclusion, findings suggest that HU and stone size differ in different anatomical structures of the urinary system. In addition, differences in stone size and composition may be associated with age and sex.

Mixed stones: urinary stone composition, frequency and distribution by gender and age

Proper analysis of urinary stone composition is a cornerstone for diagnosis, targeted treatment and recurrence prevention of urolithiasis. The aim of this study was to determine the composition, frequency and distribution of mixed stones according to gender and age of patients. A total of 42,519 urinary stones from 30,311 men and 12,208 women submitted between January 2007 and December 2020 were studied. Most urinary calculi consisted of two components (50.9%), followed by stones of a single constituent (27.1%) and three-component stones (21.9%), while four-component stones were only rarely identified (0.1%). Among all stones, 49.8% consisted of whewellite (COM), weddellite (COD), and mixtures of COM and COD, 33.8% were pure carbonate apatite (CA) and mixtures of CA with COM and/or COD, while 7.6% were composed of uric acid anhydrous (UAA), uric acid dihydrate (UAD), and mixed UAA and UAD. The remaining 8.8% of calculi were rare single-component stones and rare mixtures of various constituents. The number of stone components was inversely associated with age (p < 0.001). The proportion of men decreased significantly with the number of stone constituents, from 3.01:1 for single-component stones to 1.0:1 for four-component urinary calculi (p < 0.001). The vast majority of urinary calculi consisted of two or more components in varying proportions. While age was inversely associated with the number of stone constituents, the proportion of women increased significantly from single-component to four-component urinary calculi. A significant proportion of mixed stones could present a challenge for diagnosis and targeted recurrence prevention.

Differential oral and gut microbial structure related to systemic metabolism in kidney stone patients

OBJECTIVES

To investigate the role of the oral and gut microbiome related to systemic metabolism and clinical parameters in various types of kidney stone disease.

PATIENTS AND METHODS

We conducted a case-control study by analyzing 16S rRNA and untargeted metabolomics profiling of 76 fecal, 68 saliva, 73 urine, and 43 serum samples from 76 participants aged 18-75 years old. The participants included 15 patients with uric acid stones, 41 patients with calcium oxalate stones, and 20 healthy controls. Correlations among microbiome, metabolism, and clinical parameters were identified through Spearman's correlation analysis. (Clinical trial No. ChiCTR2200055316).

RESULTS

Patients with uric acid stones exhibited reduced richness and diversity in their microbiome, as well as altered composition in both oral and gut microbiome. Furthermore, their fecal samples showed lower relative abundances of Bacteroides and Lachnospiraceae, while their saliva samples showed higher relative abundances of Porphyromonas and Neisseria. Predicted KEGG metabolism pathways, including amino acid and fatty acid metabolisms, were significantly altered in subjects with uric acid stones. Oral, gut microbiota, and metabolism were also associated with low water intake and urine pH. The area under the curve (AUC) of the specific microbiota and metabolite prediction models was over 0.85.

CONCLUSION

The structure and composition of the oral and gut microbiome in different types of kidney stone disease, the correlations between oral and gut microbiome, and the associations among oral and gut microbiota, systemic metabolism and clinical parameters imply an important role that the oral and gut microbiome may play in kidney stone disease.

Pharmacologic treatment of kidney stones: Current medication and pH monitoring

Nephrolithiasis is a globally prevalent urologic condition associated with significant morbidity and patient discomfort. Current management of kidney stones includes both surgical and pharmacologic interventions. Though surgery may be necessary under certain circumstances, pharmacologic treatment is a more affordable, readily available, and a less invasive option for patients. A comprehensive scoping review was conducted to summarize the available literature on the pharmacologic strategies for managing the predominant stone types including calcium oxalate, calcium phosphate, uric acid, struvite, and cystine stones. Central to these therapeutic approaches is the regulation of factors such as urine pH, stone crystallization, and patient metabolics that precipitate stone development and growth. This review highlights the pharmacological options available for treating each kidney stone type, emphasizing the importance of patient tailored medical management that should be considered by every physician.

A Comparative Analysis between Flexible Ureteroscopic Lithotripsy and Tubeless Percutaneous Nephrolithotomy in the Treatment of >15 mm Non-Obstructing Proximal Ureteral Stones

BACKGROUND

The proper surgical modality for large non-obstructing proximal ureteral stones is disputed. We compare effectiveness and safety of flexible ureteroscopic lithotripsy (FURL) and tubeless percutaneous nephrolithotomy (TPNL) in treatment of upper ureteral stones larger than 1.5 cm.

METHODS

We reviewed the medical records of patients who performed FURL or TPNL for upper ureteral stones between June 2016 and November 2018. Comparative analysis was conducted regarding demographic parameters, stone free rate, postoperative pain and complications.

RESULTS

This study included 58 patients treated with FURL and 60 patients treated with TPNL owing to upper ureteral stones larger than 1.5 cm. Stone size was similar in the FURL and TPNL groups (17.6 ± 2.6 vs. 18.0 ± 2.1 mm, p = 0.194). The overall 3-month stone clearance rate was 95.8% for FURL versus 96.0% for TPNL (p = 0.575). There was no difference between the FURL and TPNL groups for hospital stay (p = 0.280) and postoperative complications. On the other hand, patients treated with FURL had longer operative time (p = 0.012) and less postoperative pain (p = 0.008).

CONCLUSIONS

Both surgical techniques were considered feasible and effective surgical procedures in the treatment of large upper ureteral stones.

Does age impact outcomes of retrograde intrarenal surgery in the elderly? Results from 366 patients from the FLEXible ureteroscopy outcomes registry (FLEXOR)

BACKGROUND

There has been a consistent increase in the last decades in prevalence of renal stones in elderly.

AIMS

To evaluate outcomes of retrograde intrarenal surgery (RIRS) for renal stones in elderly and factors associated with postoperative complications and residual fragments (RFs).

METHODS

Data from 12 centers were retrospectively reviewed.

INCLUSION CRITERIA

 ≥ 75 years, renal stones only, normal renal anatomy. Patients were divided into three groups; Group 1: patients aged 75-79 years; Group 2: age 80-84 years; Group 3: age ≥ 85 years. Multivariable logistic regression analyses were performed to assess factors associated with perioperative complications, sepsis, and RFs.

RESULTS

366 patients were included. There were 189 patients in Group 1, 113 in Group 2, and 64 in Group 3. There was no difference between groups regarding stone features and total surgical time. Median length of stay was significantly longer in Group 3 (6.0 days, vs 2.0 days in Group 2 vs 2.5 days in Group 1, p = 0.043). There was no significant difference in postoperative complications and RFs between the groups. At multivariable logistic regression analysis, female gender (OR 2.82) and maximum stone diameter (OR 1.14) were associated with higher odds of sepsis, while surgical time (OR 1.12) and the use of a reusable ureteroscope (OR 6.51) with overall complications. Stone size (OR 1.23) was associated with higher odds of RFs.

CONCLUSION

RIRS showed safety and efficacy for kidney stones in elderly patients. Surgical time should be kept as short as possible to avoid higher odds of postoperative complications, particularly in females.

A systematic review of postoperative outcomes of kidney stone surgery and meta-analysis of outcomes of percutaneous nephrolithotomy in individuals with spinal cord injury

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

To evaluate outcomes of surgical treatment for nephrolithiasis in individuals with spinal cord injury (SCI).

METHODS

We systematically reviewed the Ovid MEDLINE, Embase, CENTRAL, and Web of Science databases for studies examining outcomes of kidney stone procedures in individuals with SCI. Our primary outcomes were stone-free rate (SFR) and complications as categorized by Clavien-Dindo classification. A meta-analysis of comparative studies was performed to assess differences in SFR and complication rate between individuals with and without SCI following PCNL.

RESULTS

A total of 27 retrospective and observational articles were included. Interventions for kidney stones included PCNL, shockwave lithotripsy (SWL), and ureteroscopy. Pooled SFR in individuals with SCI was 54%, for SWL, 74% for PCNL, and 36% for ureteroscopy. Meta-analyses found that there was higher rate of grades I (OR 9.54; 95% CI, 3.06 to 29.79), II (OR 3.38; 95% CI, 1.85 to 6.18), and III-V (OR 2.38; 95% CI, 1.35 to 4.19) complications in individuals with SCI compared to non-SCI individuals following PCNL. The rate of infectious complications was also higher in individuals with SCI (OR 6.15; 95% CI, 1.86 to 20.39). However, there was no difference in SFR (OR 0.64; 95% CI, 0.15 to 2.64) between groups.

CONCLUSIONS

Individuals with SCI are at higher risk of minor, major, and infectious complications following PCNL compared to non-SCI individuals. There was no significant difference between groups in SFR following PCNL, suggesting that PCNL is an effective surgery for kidney stones in individuals with SCI.

Retrospective analysis of urinary tract stone composition in a Chinese ethnic minority colony based on Fourier transform infrared spectroscopy

To analyze the relationship between the composition of urinary stones and various influencing factors in the Enshi region. We used FT-IR to examine the composition of 1092 stone samples. Combined with the relevant clinical materials, the data were analyzed using both one-dimensional statistical methods and multivariate statistical methods. The study included 1092 stone samples, classified as follows: 457 (41.8%) with a single component, 453 (41.5%) with two components, 149 (13.6%) with three components, and 33 (3.0%) with four components. Stones were categorized into five types: Calcium Oxalate (CaOx) (76.4%), carbapatite (CaP) (9.3%), Struvite (ST) (8.3%), Uric Acid (UA) (4.9%), and Others (1.0%). Age, gender, urinary tract infection (UTI), family history of urinary stones (FH), hyperuricemia (HUA) and stone location were significantly associated with stone type. Logistic regression revealed that females and UTI were relative risk factors for predicting CaP and ST, while FH and HUA were relative risk factors for predicting UA. Our study indicates that the overall composition of urinary tract stones in the Enshi region is consistent with that of the entire China. Additionally, the predisposing factors for stone formation vary in terms of gender, age, FH, UTI, hyperuricemia HUA, and stone location.

Comparative efficacy between retrograde intrarenal surgery with vacuum-assisted ureteral access sheath and minimally invasive percutaneous nephrolithotomy for 1-2 cm infectious upper ureteral stones: a prospective, randomized controlled study

Objective

To observe the efficacy and safety of retrograde intrarenal surgery combined with vacuum-assisted ureteral access sheath (V-UAS) and minimally invasive percutaneous nephrolithotomy (MPCNL) in patients with 1-2 cm infectious upper ureteral stone.

Patients and methods

A total of 173 patients with 1-2 cm infectious upper ureteral stone were prospectively randomized into two groups. Eighty-six in the V-UAS group and 87 cases as control in the MPCNL group. The SFRs at different times (Postoperative 1 day, 2nd week and 4th week) was considered as the primary outcome of the study. The secondary end points were operative time, postoperative hospital stay and operative complications.

Results

There was no obvious difference between two groups in patients' demographics and preoperative clinical characteristics (all P > 0.05). Postoperative data showed that the SFR at postoperative 1 day in the V-UAS group was significantly lower than that in the MPCNL group (73.2% vs. 86.2%, P = 0.034). However, there was no statistical significance between two groups in SFRs during postoperative 2 weeks and 4 weeks (All P > 0.05). The levels of WBC, CRP and PCT were all significant lower in the V-UAS group than those in the MPCNL group at the postoperative 24 h and 48 h (all P < 0.05). Postoperative complications included fever (≥38.5°C), bleeding, pain and urosepsis. In terms of the rates of fever, pain and urosepsis, MPCNL group were all significantly higher than those in the V-UAS group (10.3 vs. 2.4%, P = 0.031; 14.9 vs. 2.4%, P = 0.003; 4.6 vs. 0.0%, P = 0.044; respectively). No significant difference was found between two groups in bleeding. Meanwhile, postoperative hospital stay in the V-UAS group was more shorten than that in the MPCNL group (3.7 vs. 5.9 days, P < 0.001).

Conclusions

Our study showed that RIRS with V-UAS, a new partnership to treat 1-2 cm infectious upper ureteral stones, was satisfying as it achieved a high SFR rate and a low rate of infectious complications. This method was safe and reproducible in clinical practice.

Butyric acid inhibits oxidative stress and inflammation injury in calcium oxalate nephrolithiasis by targeting CYP2C9

This study investigates the mechanism by which butyric acid can protect against calcium oxalate (CaOx) nephrolithiasis. To do so, a rat model was used with 0.75% ethylene glycol administration to induce CaOx crystal formation. Histological and von Kossa staining revealed calcium deposits and renal injury, while dihydroethidium fluorescence staining was used to detect reactive oxygen species (ROS) levels. Flow cytometry and TUNEL assays were used to assess apoptosis, respectively. Treatment with sodium butyrate (NaB) was found to partially reverse the oxidative stress, inflammation, and apoptosis associated with CaOx crystallization in the kidney. In addition, in HK-2 cells, NaB reversed the decreased cell viability, increased ROS levels and apoptosis damage caused by oxalate exposure. Network pharmacology was employed to predict the target genes of butyric acid, CYP2C9. Subsequently, NaB was found to significantly reduce CYP2C9 levels in vivo and in vitro, and inhibition of CYP2C9 by Sulfaphenazole (a specific CYP2C9 inhibitor), was able to reduce ROS levels, inflammation injury, and apoptosis in oxalate-induced HK-2 cells. Collectively, these findings suggest that butyric acid may inhibit oxidative stress and reduce inflammation injury in CaOx nephrolithiasis by suppressing CYP2C9.

Untargeted and targeted metabolomics reveal bile acid profile changes in rats with ethylene glycol-induced calcium oxalate nephrolithiasis

Calcium oxalate (CaOx) nephrolithiasis is a prevalent disorder linked to metabolism. Examining metabolic alterations could potentially give an initial understanding of the origins of CaOx nephrolithiasis. This study aims to determine gut metabolic biomarkers differentiating CaOx nephrolithiasis utilizing untargeted and targeted metabolomics. CaOx nephrolithiasis model rats were built by 1% ethylene glycol administration. Histologic staining and renal function measurement revealed the presence of crystals in the lumen of the renal tubules, the renal injury and interstitial fibrosis in CaOx rats, demonstrating that the models of CaOx were established successfully. Hematoxylin & eosin (H&E) staining showed that CaOx group had inflammation and damage in the ileal tissue. Immunofluorescence and PCR results displayed that the tight junction proteins, ZO-1 and Occludin levels were decreased in the ileal tissues of the CaOx group. The untargeted metabolomic analysis revealed that 269 gut metabolites were differentially expressed between the CaOx group and the control group. Meanwhile, bile secretion, the main metabolic pathway in CaOx nephrolithiasis, was identified. Following, five significant bile acid metabolites were selected utilizing the targeted bile acid metabolomics, including Hyodeoxycholic acid (HDCA), Glycohyodeoxycholic acid (GHDCA), Nor-Deoxycholic Acid, omega-muricholic acid, and Taurolithocholic acid. Among these metabolites, HDCA and GHDCA presented the highest predictive accuracy with AUC = 1 to distinguish the CaOx group from the control group. As a result of network pharmacology, target genes of HDCA and GHDCA in CaOx nephrolithiasis were enriched in oxidative stress and apoptosis pathways. Conclusively, our study provides insight into bile acids metabolic changes related to CaOx nephrolithiasis. Although alterations in biochemical pathways indicate a complex pathology in CaOx rats, bile acid changes may serve as biomarkers of CaOx nephrolithiasis.

Active stone removal is a safe option for ocotogenarians and nonagenarians with nephrolithiasis

PURPOSE

To assess the contemporary in-hospital management of octogenarians and nonagenarians with renal calculi.

MATERIAL AND METHODS

A multicentric retrospective evaluation of patients aged ≥ 80 years hospitalized with kidney stones between 01/2000 and 12/2019. Stone and patient related data were collected, including stone size and location, geriatric status and comorbidities. Surgical treatment patterns and outcome were assessed.

RESULTS

A total of 299 patients (57% female) with kidney stones were analyzed. Mean age was 84.7 years. Patients were largely multimorbid (ASA ≥ 3 in 70%) and about 25% were classified as frail. Active stone treatment was performed in 65% and 35% were treated with urinary diversion (stent or nephrostomy). Prognostic factors for receiving an active stone treatment were age < 90 years, male sex, stone size and quantity, and performance status. Mean overall survival was 23.7 months and when stratified to treatment mean survival were 21 months after urinary diversion, 28 months after URS, 29 months after PCNL and 45 months after SWL.

CONCLUSION

Age, frailty and performance-status as well as stone size and quantity are predictors for active stone treatment. Octogenarians and nonagenarians, who are considered fit for surgery, tend to live long enough to profit from active stone treatment.

In-vivo or in-vitro stone attenuation: what is more valuable for the prediction of renal stone composition in non-contrast-enhanced abdominal computed tomography?

OBJECTIVES

To compare the efficacy of in-vivo and in-vitro stone attenuation in the prediction of stone composition using non-contrast-enhanced abdominal computed tomography (NCCT).

METHODS

This study included a total of 104 patients with renal stones who received percutaneous nephrolithotomy treatment for renal stones between December 2016 and December 2019 and underwent NCCT before the procedure. Preoperative (in-vivo) and postoperative (in-vitro) kidney stone attenuations were compared using the NCCT images of the patients. Renal stone fragments were analysed with the infrared spectrophotometer method.

RESULTS

The mean age of the 104 patients was 49.5 (interquartile range: 37-61) years. According to the receiver operating characteristics analysis, the cut-off values for the prediction of uric acid stones were determined to be 556 HU for the in-vivo and 774 HU for the in-vitro attenuation measurement. Sensitivity and specificity were 100% and 96.6%, respectively, for the in-vivo and 90.9 and 91%, respectively, for the in-vitro images. The cut-off values for the prediction of calcium stones were determined to be 824 HU and 1065 HU for the in-vivo and in-vitro attenuation measurements, respectively. Sensitivity and specificity were 97.3 and 96% for the in-vivo and 96 and 96% for the in-vitro images.

CONCLUSIONS

In-vivo stone attenuation measurement in NCCT was slightly superior to in-vitro measurement due to the reduction in the composition and size of the stone. Our findings show that NCCT in-vivo stone attenuation might differentiate uric acid and calcium stones from the other stone types.

Acute kidney injury increases risk of kidney stones-a retrospective propensity score matched cohort study

BACKGROUND

Acute kidney injury (AKI) is common. An episode of AKI may modify the risk of developing kidney stones by potential long-term effects on urine composition. We aimed to investigate the association between AKI and the risk of kidney stone presentations.

METHODS

The retrospective cohort study used patient data (1 January 2008-31 December 2017), from an Australian Local Health District, which included AKI diagnosis, demographics, comorbidities and kidney stone admissions. Time-varying Cox proportional hazards and propensity-matched analysis were used to determine the impact of AKI on the risk of kidney stones. To address possible population inhomogeneity in comparisons between no AKI and hospitalized AKI, sub-group analysis was done comparing inpatient and outpatient AKI versus no AKI, to assess consistency of association with future stones. Sensitivity analysis was undertaken to capture the impact of a known AKI status and AKI severity.

RESULTS

Out of 137 635 patients, 23 001 (17%) had an AKI diagnosis and 2295 (2%) had kidney stone presentations. In the unadjusted analysis, AKI was associated with kidney stones, with AKI used as a time-varying exposure, [hazard ratio (HR) 1.32, 95% confidence interval (CI) 1.16-1.50)]. Both inpatient-AKI (HR 1.19, 95% CI 1.01-1.39) and outpatient-AKI (HR 1.59, 95% CI 1.30-1.94) were significantly associated with future stones compared to no AKI subjects. This association persisted in the adjusted analysis (HR 1.45, 95% CI 1.26-1.66), propensity-matched dataset (HR 1.67, 95% CI 1.40-1.99) and sensitivity analysis. There was a dose-response relationship with higher stages of AKI being associated with a greater risk of kidney stones.

CONCLUSIONS

In a large cohort of patients, AKI is associated with a greater risk of kidney stones, which increases with higher stages of AKI. This association should be examined in other cohorts and populations for verification.

Ureteral calculi in octogenarians and nonagenarians: Contemporary in-hospital management-A joint study by the endourological section of the Austrian Association of Urology

AIM

To assess contemporary in-hospital management of octogenarians and nonagenarians with ureteral calculi.

MATERIALS AND METHODS

Review of patients aged ≥80 years hospitalized due to ureteral calculi. Data was extracted from eight Austrian centers of urology. Stone and patient related data were recorded. Treatment patterns in acute and elective settings were assessed.

RESULTS

A total of 759 patients hospitalized with ureteral calculi were analyzed. Out of them, 643 were octogenarians (80-89years) and 116 nonagenarians (90-99 years). In an acute setting, simple de-obstruction with urinary diversions outnumbered active stone treatments like URS and SWL (62.6% vs. 26.9% vs. 10.5%). Decision making whether patients underwent active stone treatment was driven by stone location (OR = 0.28, p<0.0001), impaired renal function (OR = 0.28, p = 0.01) and indwelling urethral catheters (OR = 0.23, p = 0.01) but not by age or extend of mobility (all p>0.05). In elective settings, 81.5% of procedures were active stone treatments-mainly URS (76.9%), while DJ stent or nephrostomy replacements were noted in 14.2% and 4.3%. Octogenarians (OR = 14, p<0.0001) and patients capable of walking (OR = 4.51, p = 0.01) had significantly higher odds of receiving active stone. Stone free rates and complications rates with URS were similar between octogenarians and nonagenarians (p = 0.98 and p = 0.58).

CONCLUSION

In acute settings, age and extend of mobility were not found to be independent predictors for active stone treatment. In elective settings, after having received urinary diversions, reduced mobility and nonagenarians were less likely to undergo stone removal treatments. Safety and efficacy of URS seems to be similar in octogenarians and nonagenarians.

Spectrum of Bacterial Pathogens from Urinary Infections Associated with Struvite and Metabolic Stones

OBJECTIVE

The purposes of this multi-center study were to evaluate the rate of infection stones and to evaluate the urine cultures of patients with infection stones.

MATERIALS

Charts of adulpatients with urinary stones were reviewed and data on stone analyses and urine cultures were collected.

RESULTS

In total, 1204 renal stone formers (RSFs) from 10 countries were included (776 males, 428 females). Fifty-six patients (4.6%) had struvite stones. The highest frequency of struvite stones was observed in India (23%) and Pakistan (18%). Lower rates were reported in Canada (2%), China (3%), Argentina (3%), Iraq (3%), Italy (3.5%) and Poland (3%), and intermediate rates in Egypt (5.5%) and Bulgaria (5.4%). Urine cultures were retrieved from 508 patients. Patients with struvite stones had a positive culture in 64.3% of the samples and patients with other stones, in 26.7%. In struvite stones, the most common isolates were Escherichia coli (27.7%) and Proteus spp. (27.7%), followed by Klebsiella spp. (16.7%); in other types of stone, it was Escherichia coli (47.6%), followed by Gram-positive bacteria (14.0%) Conclusions: The struvite stone composition was associated with a urinary infection, although an infection was not demonstrable with a conventional midstream urine culture in about 30%.

How useful is an oral calcium load test for diagnosing recurrent calcium stone formers?

Hypercalciuria is the main risk factor for recurrent calcium urolithiasis. The goal of our study is to determinate how useful an oral calcium load test is for stone formers to classify different forms of hypercalciuria in pathogenetic categories defined as renal or absorptive according to the current knowledge. Between June 2013 and February 2016, a prospective study was carried out on 117 documented recurrent hypercalciuric stone formers undergoing an oral calcium load test modified from the original description by Pak. After 2 days of calcium-restricted diet, urine and blood were analyzed at baseline and 120 min after receiving orally 1 g of calcium. Total and ionized calcium, parathyroid hormone from serum and urine calcium and creatinine were assessed in order to divide patients in three groups as previously described: resorptive, absorptive, and renal hypercalciuria. This allowed the identification of 19, 39, 34 and 33 patients with normocalcemic primary hyperparathyroidism (NPHPT), renal hypercalciuria aka renal calcium leak (RCL), absorptive hypercalciuria (AH) and unidentified cause, respectively. Patients with NPHPT (who required parathyroidectomy) experienced a lower PTH decrease (41.41 ± 12.82 vs. 54.06 ± 13.84% p < 0.01), higher beta-crosslaps, as well as lower TmP/GFR and distal third radius bone mineral density. RCL resulted in increased fasting urine calcium-to-creatinine ratio (Uca/Cr), i.e., > 0.37 mmol/mmol), without hyperparathyroidism. AH was diagnosed by the presence of ΔUCa/Cr > 0.60 mmol/mmol between baseline and 120 min without any other anomaly. For all remaining patients, results were inconclusive due to the lack of sufficient increase in serum calcium or because the cause of lithogenesis could not be clearly identified. The oral calcium load test is useful in nearly 80% of patients by identifying the different forms of hypercalciuria causing urolithiasis and by guiding treatment, including parathyroid surgery.

A nationwide registry for recurrent urolithiasis in the upper urinary tract – The RECUR study protocol

Background

Urinary stone disease is a widespread disease with tremendous impact on those affected and on societies around the globe. Nevertheless, clinical and health care research in this area seem to lag far behind cardiovascular diseases or cancer. This may be due to the lack of an immediate deadly threat from the disease and therefore less public and professional interest. However, the patients suffer from recurring, sometimes intense pain and often must be treated in hospital. Long-term morbidity includes doubled rates of chronic kidney disease and arterial hypertension after at least one stone-related event. Observational studies, more specifically, registries and other electronic data sets have been proposed as a means of filling critical gaps in evidence. We propose a nationwide digital and fully automated registry as part of the German Ministry for Education and Research (BMBF) call for the "establishment of model registries”.

Methods

RECUR builds on the technical infrastructure of Germany’s Medical Informatics Initiative. Local data integration centres (DIC) of participating medical universities will collect pseudonymized and harmonized data from respective hospital information systems. In addition to their clinical data, participants will provide patient reported outcomes using a mobile patient app. Scientific data exploration includes queries and analysis of federated data from DICs of eleven participating sites. All primary patient data will remain at the participating sites at all times. With comprehensive data from this longitudinal registry, we will be able to describe the disease burden, to determine and validate risk factors, and to evaluate treatments. Implementation and operation of the RECUR registry will be funded by the BMBF for five years. Subsequently, the registry is to be continued by the German Society of Urology without significant costs for study personnel.

Discussion

The proposed registry will substantially improve the structural and procedural framework for patients with recurrent urolithiasis. This includes advanced diagnostic algorithms and treatment pathways. The registry will help us identify those patients who will most benefit from specific interventions to prevent recurrences. The RECUR study protocol and the registry’s technical architecture including full digitalization and automation of almost all registry-associated proceedings can be transferred to future registries.

Trial registration

This study is registered at the German Clinical Trial Register (Deutsches Register Klinischer Studien), DRKS-ID DRKS00026923, date of registration January, 11^th 2022.

Modification effect of changes in cardiometabolic traits in association between kidney stones and cardiovascular events

Backgrounds

Whether longitudinal changes in metabolic status influence the effect of kidney stones on cardiovascular disease (CVD) remains unclarified. We investigated the modification effect of status changes in metabolic syndrome (MetS) in the association of kidney stones with risk of incident CVD events.

Methods

We performed a prospective association and interaction study in a nationwide cohort including 129,172 participants aged ≥ 40 years without CVDs at baseline and followed up for an average of 3.8 years. Kidney stones information was collected by using a questionnaire and validated by medical records. The repeated biochemical measurements were performed to ascertain the metabolic status at both baseline and follow-up.

Results

4,017 incident total CVDs, 1,413 coronary heart diseases (CHDs) and 2,682 strokes were documented and ascertained during follow-up. Kidney stones presence was significantly associated with 44%, 70% and 31% higher risk of CVDs, CHDs and stroke, respectively. The stratified analysis showed significant associations were found in the incident and sustained MetS patients, while no significant associations were found in the non-MetS at both baseline and follow-up subjects or the MetS remission ones, especially in women. For the change status of each single component of the MetS, though the trends were not always the same, the associations with CVD were consistently significant in those with sustained metabolic disorders, except for the sustained high blood glucose group, while the associations were consistently significant in those with incident metabolic disorders except for the incident blood pressure group. We also found a significant association of kidney stone and CVD or CHD risk in the remain normal glucose or triglycerides groups; while the associations were consistently significant in those with incident metabolic disorders except for the incident blood pressure group. We also found a significant association of kidney stone and CVD or CHD risk in the remain normal glucose or triglycerides groups.

Conclusions

A history of kidney stones in women with newly developed MetS or long-standing MetS associated with increased risk of CVD. The mechanisms link kidney stones and CVD risk in the metabolic and non-metabolic pathways were warranted for further studies.

The effect of metabolic risk factors on urinary stone composition: An observational study

To investigate how the risk factors of metabolic diseases affect urinary stone composition, particularly uric acid (UA) stones. Overall, 583 patients with data on urinary stone composition were retrospectively analyzed and classified into UA and nonUA stone formers according to the presence of the UA component. Various factors were compared between both groups. Participants were categorized according to age, glucose level, HbA1c level, and estimated glomerular filtration rate (eGFR) into subgroups, and the incidence of UA stone was compared. Overall, 137 UA stone formers (23.5%) and 446 nonUA stone formers (76.5%) were included. Mean age and male-to-female ratio were higher in the UA group than in the nonUA group. The rates of diabetes mellitus (DM), hypertension, chronic kidney disease, and coronary artery disease, all of which were associated with differences in urinary stone composition, were higher in the UA group than in the nonUA group. The UA group exhibited lower mean eGFR and higher glucose and HbA1c levels. Similarly, the UA group had higher mean UA levels and predictably lower urinary pH. In subgroup analysis, higher age, glucose level, HbA1c level, and lower eGFR were associated with an increased risk of UA stone formation. In the multivariate logistic regression analysis, the UA group showed a significantly higher age (P < .001), DM frequency (P = .049), and HbA1c level (P = .032), but significantly lower eGFR than the nonUA group (P < .001). Age and DM were independent risk factors for UA urolithiasis, implying a relationship between urinary stone composition and metabolic diseases. Additionally, renal function and HbA1c level were risk factors for UA stones.

Urinary stone composition in Germany: results from 45,783 stone analyses

PURPOSE

Stone composition can provide valuable information for the diagnosis, treatment and recurrence prevention of urolithiasis. The aim of this study was to evaluate the distribution of urinary stone components and the impact of different crystal forms according to gender and age of patients in Germany.

METHODS

A total of 45,783 urinary stones submitted from 32,512 men and 13,271 women between January 2007 and December 2020 were analyzed by infrared spectroscopy. Only the first calculus obtained per patient was included in the analysis.

RESULTS

The most common main stone component was calcium oxalate (CaOx) (71.4%), followed by carbonate apatite (CA) (10.2%) and uric acid (UA) (8.3%). Struvite (2.1%), brushite (1.3%), protein (0.5%) and cystine (0.4%) stones were only rarely diagnosed. CaOx (75%) and UA stones (81%) were more frequently obtained from men than women (p < 0.001). Weddellite (COD) and uric acid dihydrate (UAD) were more common in younger ages than whewellite (COM) and anhydrous uric acid (UAA), respectively, in both men and women. The ratios of COM-to-COD and UAA-to-UAD calculi were approximately 4:1 and 8:1, respectively. The peak of stone occurrence was between the ages of 40 and 59 years.

CONCLUSION

Stone composition is strongly associated with gender and age. The peak incidence of calculi in both women and men was in the most active phase of their working life. The distinction between different crystal forms could provide clues to the activity and mechanisms of lithogenesis. Further research is needed in understanding the causative factors and the process of stone formation.

Supine versus prone percutaneous nephrolithotomy for renal calculi: Our experience

Objectives:

To compare operative times, safety, and effectiveness of percutaneous nephrolithotomy in the supine versus the prone position.

Materials and methods:

An observational study of 100 patients was conducted in our institution for 2years from 2018 to 2020 divided into 2 groups: 50 patients underwent modified supine percutaneous nephrolithotomy (PCNL) and 50 patients underwent standard prone PCNL. The inclusion criteria included a renal calculus (calyx or pelvis) of any size for which PCNL was indicated and exclusion criteria were patients having contraindications for PCNL such as bleeding disorders, pregnancy, high risk, and co-morbid conditions. The measured data included operative time, number of punctures, stone-free rate, length of hospital stays, and rate of complications.

Results:

The 2 groups were comparable in mean age, male to female ratio, calculus size, number of punctures, residual calculi, and postoperative fever and pain. The mean difference of hemoglobin in the supine PCNL group was 0.37 g/dL whereas in the prone PCNL group it was 0.61 g/dL. The p value was significant at 0.043. The mean time to finish from initial postion was 72.24 minutes in supine PCNL and 88.12 minutes in prone PCNL. The p value was significant (p < 0.001). The mean time before puncture was 20.92 minutes in the supine position and 31.84 minutes in the prone position. The p value was significant (p < 0.001). The mean time from puncture to finish was 51.32 minutes in the supine position and 56.28 minutes in the prone position. The p value was significant (p < 0.001).

Conclusions:

As observed from this study, supine PCNL is associated with a significantly reduced operating time when compared to conventional prone position PCNL procedures. The postoperative complications such as pain and fever were not significantly different. Hence, the supine PCNL is an equally effective modality for treatment of a renal calculus with benefits of simultaneous retrograde access and less operative time compared to the prone PCNL.

miR-103a-3p Silencing Ameliorates Calcium Oxalate Deposition in Rat Kidney by Activating the UMOD/TRPV5 Axis

Maintaining the balance of calcium (Ca2+) metabolism in the kidney is crucial in preventing the formation of kidney stones. Functionally, the microRNA (miRNA) participating in this process needs to be unveiled. We induced NRK-52E cell injury by oxalate treatment. The role of transient receptor potential cation channel subfamily V member 5 (TRPV5) in oxalate-induced cells was studied by TRPV5 overexpression transfection, qRT-PCR, Western blot, MTT, and crystal adhesion detection. After identifying uromodulin (UMOD) expression in injured cells, we confirmed the interaction between TRPV5 and UMOD by coimmunoprecipitation (CoIP) and cell-surface biotinylation assays. The validation of UMOD-regulating TRPV5 in viability, crystal adhesion, and Ca2+ concentration of oxalate-induced cells was performed. Bioinformatics analysis and luciferase assay were used to identify the miRNA-targeting UMOD. The role of the miR-103a-3p-regulating UMOD/TRPV5 axis was detected by rescue experiments. We constructed a rat model with treatment of ethylene glycol (EG) to investigate the miR-103a-3p/UMOD/TRPV5 axis in vivo by hematoxylin-eosin (H&E) staining, Western blot, and immunohistochemistry (IHC). Upregulation of TRPV5 protected NRK-52E cells from oxalate-induced injury by enhancing cell viability and inhibiting CaOx adhesion. UMOD was depleted in oxalate-induced cells and positively interacted with TRPV5. UMOD silencing reversed the effect of TRPV overexpression on oxalate-induced cells. miR-103a-3p targeted UMOD and was mediated in the regulation of the UMOD/TRPV5 axis in oxalate-induced cells. Downregulating miR-103a-3p mitigated EG-induced CaOx deposition in kidney tissues in vivo by activating the UMOD/TRPV5 axis. miR-103a-3p silencing ameliorated CaOx deposition in the rat kidney by activating the UMOD/TRPV5 axis.

Epidemiological Trends of Urolithiasis at the Global, Regional, and National Levels: A Population-Based Study

BACKGROUND

Urolithiasis is common worldwide and can predispose to urinary tract infections and renal failure. We aimed to explore the global, regional, and national burden of urolithiasis between 1990 and 2019, stratified by sex, age, and sociodemographic index (SDI).

METHODS

From 1990 to 2019, data on the number of incident cases of urolithiasis, associated deaths, and disability-adjusted life years (DALYs) were extracted from the 2019 Global Burden of Disease (GBD) study. The trends for the incidence rate, mortality, and DALYs were evaluated using estimated annual percentage changes (EAPCs).

RESULTS

The incidence of urolithiasis increased by 48.57%, from 77.78 million incident cases in 1990 to 115.55 million in 2019, while its age-standardized incidence rate (ASIR) decreased. The ASIR increased slightly in the low SDI regions (EAPC = 0.33; 95% confidence interval [CI]: 0.24-0.43), while ASIRs in other SDI regions decreased. The incidence of urolithiasis by age presented a unimodal distribution, with the peak observed in patients aged between 50 years and 70 years. Urolithiasis-related mortality and DALYs also increased over time. Yet, the age-standardized death rate (ASDR) decreased by 2.05% (95% CI, -2.25% to -1.85%) per year, and the annual age-standardized DALY rate decreased by 1.77% (95% CI, -1.92% to -1.63%). The mortality and DALYs increased with age. The incidence, mortality, and DALYs were greater in males than those in females. The burden of urolithiasis showed obvious differences in its regional distribution over the past three decades.

CONCLUSION

From 1990 to 2019, ASIR, ASDR, and age-standardized DALY rate of urolithiasis have decreased. Yet, particularly significant differences exist in the geographic, age, and sex distribution. Thus, medical resources should be rationally allocated and adjusted according to the geographic and demographic distribution of urolithiasis.

Oxalate Flux Across the Intestine: Contributions from Membrane Transporters

Epithelial oxalate transport is fundamental to the role occupied by the gastrointestinal (GI) tract in oxalate homeostasis. The absorption of dietary oxalate, together with its secretion into the intestine, and degradation by the gut microbiota, can all influence the excretion of this nonfunctional terminal metabolite in the urine. Knowledge of the transport mechanisms is relevant to understanding the pathophysiology of hyperoxaluria, a risk factor in kidney stone formation, for which the intestine also offers a potential means of treatment. The following discussion presents an expansive review of intestinal oxalate transport. We begin with an overview of the fate of oxalate, focusing on the sources, rates, and locations of absorption and secretion along the GI tract. We then consider the mechanisms and pathways of transport across the epithelial barrier, discussing the transcellular, and paracellular components. There is an emphasis on the membrane-bound anion transporters, in particular, those belonging to the large multifunctional Slc26 gene family, many of which are expressed throughout the GI tract, and we summarize what is currently known about their participation in oxalate transport. In the final section, we examine the physiological stimuli proposed to be involved in regulating some of these pathways, encompassing intestinal adaptations in response to chronic kidney disease, metabolic acid-base disorders, obesity, and following gastric bypass surgery. There is also an update on research into the probiotic, Oxalobacter formigenes, and the basis of its unique interaction with the gut epithelium. © 2021 American Physiological Society. Compr Physiol 11:1-41, 2021.

Short-Chain Fatty Acids Reduced Renal Calcium Oxalate Stones by Regulating the Expression of Intestinal Oxalate Transporter SLC26A6

Renal calcium oxalate (CaOx) stone is a common urologic disease with a high prevalence and recurrence rate. However, short-chain fatty acids (SCFAs) are less often reported in the prevention of urolithiasis. This study aimed to explore the effect of SCFAs on the renal CaOx stone formation and the underlying mechanisms. Ethylene glycol was used to induce renal CaOx crystals in rats. SCFAs (acetate, propionate, or butyrate) were added as supplements to the drinking water with or without antibiotics. Because intestinal oxalate transporters SLC26A6 and SLC26A3 regulate the excretion and absorption of oxalate in the intestine, we injected adeno-associated virus 9 (AAV9)-SLC26A6-shRNA (short hairpin RNA) and AAV9-SLC26A3 into the tail vein of rats to suppress SLC26A6 and overexpress SLC26A3 expression in the intestine, respectively, to explore the role of SLC26A3 and SLC26A6 (SLC26A3/6) in the reduction of renal CaOx crystals induced by SCFAs. Results showed that SCFAs reduced renal CaOx crystals and urinary oxalate levels but, however, increased the abundance of SCFA-producing bacteria and cecum SCFA levels. SCFA supplements still reduced renal crystals and urinary oxalate after gut microbiota depletion. Propionate and butyrate downregulated intestinal oxalate transporter SLC26A3 expression, while acetate and propionate upregulated SLC26A6 expression, both in vivo and in vitro. AAV9-SLC26A3 exerted a protective effect against renal crystals, while AAV9-SLC26A6-shRNA contributed to the renal crystal formation even though the SCFAs were supplemented. In conclusion, SCFAs could reduce urinary oxalate and renal CaOx stones through the oxalate transporter SLC26A6 in the intestine. SCFAs may be new supplements for preventing the formation of renal CaOx stones. IMPORTANCE Some studies found that the relative abundances of short-chain-fatty-acid (SCFA)-producing bacteria were lower in the gut microbiota of renal stone patients than healthy controls. Our previous study demonstrated that SCFAs could reduce the formation of renal calcium oxalate (CaOx) stones, but the mechanism is still unknown. In this study, we found that SCFAs (acetate, propionate, and butyrate) reduced the formation of renal calcium oxalate (CaOx) crystals and the level of urinary oxalate. Depleting gut microbiota increased the amount of renal crystals in model rats, and SCFA supplements reduced renal crystals and urinary oxalate after gut microbiota depletion. Intestinal oxalate transporter SLC26A6 was a direct target of SCFAs. Our findings suggested that SCFAs could reduce urinary oxalate and renal CaOx stones through the oxalate transporter SLC26A6 in the intestine. SCFAs may be new supplements for preventing the formation of renal CaOx stones.

Influence of Age and Geography on Chemical Composition of 98043 Urinary Stones from the USA

Background

Urolithiasis is a growing issue globally, but it is heterogeneous, with a different epidemiology and pathophysiology for each different stone composition.

Objective

The purpose of this study is to describe the incidence of urinary stones in the USA from 2016 to 2019 by chemical composition and to investigate the influence of age and geography on these stone types.

Design, setting, and participants

We obtained compositional analyses for all urinary stones submitted to a national laboratory over an approximately 3-yr period.

Outcome measurements and statistical analysis

Data collected included the chemical constituents of a stone, patient age, and geographical origin. We describe the incidence of each stone type by frequency. Statistical testing was performed to determine the influence of age and geographical region on overall incidence of each stone composition.

Results and limitations

In total, 99 908 specimens were analyzed. When pure stones were ordered by frequency, we found that the most common stone type was calcium oxalate (CaOx) (79.2%), followed by uric acid (UA; 14.3%), calcium phosphate (CaPO₄; 3.7%), cystine (0.51%), drug induced (0.12%), and magnesium ammonium phosphate (0.04%). CaOx, UA, and CaPO₄ were often mixed with one another. Among CaOx stones, the plurality (28.0%) was made of pure calcium oxalate monohydrate (COM), and only 0.002% was pure calcium oxalate dihydrate. There was an overall association between stone composition and both geographical distribution and age (p < 0.001).

Conclusions

CaOx stones comprise the majority of urinary stones in the USA, of which almost 28% were pure COM. Additionally, age and geographical region are significantly associated with variations in stone composition.

Patient summary

We evaluated the incidence of urinary stones in the USA based on their chemical composition. The most common stone type was calcium oxalate, the majority of which was pure calcium oxalate monohydrate. We also found age and geographical region to be significantly associated with variations in stone composition.

Association between aortic calcification and the presence of kidney stones: calcium oxalate calculi in focus

PURPOSE

The current research is aimed at analyzing the relationship between kidney stone (KS) and abdominal aortic calcification (AAC) and the relationship between KS components and AAC.

METHODS

This is a retrospective, case-control study. Kidney stone formers (KSFs) were treated at the Department of Urology, West China Hospital, Sichuan University for urological calculus disease from January 2014 to January 2020. Matched non-stone formers (non-SFs) were drawn from the same hospital for routine health examination from January 2018 to February 2019. Research-related information was collected and reviewed retrospectively from the hospital's computerized records. AAC were evaluated using available results of computed tomography imaging and abdominal vascular ultrasound. The relationships of AAC between KSFs and non-SFs were compared. The composition of renal calculi was analyzed by Fourier-transform infrared spectrophotometer. KSFs were divided into AAC groups and non-AAC based on AAC. The relationship of the composition of renal calculi between AAC and non-AAC were compared. The independent-sample t test, the chi-squared test and binary logistics regression were performed.

RESULTS

Altogether, 4516 people were included, with 1027 KSFs and 3489 non-SFs. There were no significant differences in the laboratory parameters between KSFs and non-SFs. The association between the presence of AAC and KS was significant in multivariable model 2 [adjusting hypertension, diabetes mellitus, fasting blood glucose, uric acid, serum triglyceride (TG), serum calcium, and urine pH] (OR 5.756, 95% CI 4.616-7.177, p < 0.001). The result of KSFs showed that calcium oxalate calculi (CaOx) was significantly associated with AAC in multivariable model 3 (adjusting age, hypertension, diabetes mellitus, drinking history, smoking history, and TG) (OR 1.351, 95% CI 1.002-1.822, p = 0.048).

CONCLUSIONS

The current study pioneered the revelation of the relationship between CaOx and AAC. Through an elimination of the confounding factors, the study demonstrated that KS and AAC were connected.

Mechanisms Underlying Calcium Nephrolithiasis

Nephrolithiasis is a worldwide problem with increasing prevalence, enormous costs, and significant morbidity. Calcium-containing kidney stones are by far the most common kidney stones encountered in clinical practice. Consequently, hypercalciuria is the greatest risk factor for kidney stone formation. Hypercalciuria can result from enhanced intestinal absorption, increased bone resorption, or altered renal tubular transport. Kidney stone formation is complex and driven by high concentrations of calcium-oxalate or calcium-phosphate in the urine. After discussing the mechanism mediating renal calcium salt precipitation, we review recent discoveries in renal tubular calcium transport from the proximal tubule, thick ascending limb, and distal convolution. Furthermore, we address how calcium is absorbed from the intestine and mobilized from bone. The effect of acidosis on bone calcium resorption and urinary calcium excretion is also considered. Although recent discoveries provide insight into these processes, much remains to be understood in order to provide improved therapies for hypercalciuria and prevent kidney stone formation. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Retrospective epidemiological study of urolithiasis in western Algeria over a period of 50 years

Background

Urolithiasis is a pathology that changes with time and with the evolution of human societies. The prevalence of this pathology has gradually increased during the last decades, especially because of dietary changes.

Methods

This work is a retrospective descriptive epidemiological study of the temporal type carried out at the level of the urology service of the University Hospital Center of Oran between the first January 1965 and December 31, 2014. The objectives of this work are to study the epidemiological profile of urolithiasis and to determine the evolutionary trend of the disease over time.

Results

This study confirms some current data in the direction of an increase in surgical activity concerning the treatment of urinary stones. The analysis over time shows us a significant decrease (p < 0.01) in the male predominance between 1965 and 2014 with a M/F ratio which decreased from 3.09 to 1.82, as well as an increase in the average age, rising from 28.8 years in the period 1965–1974 to 48.3 years between 2005 and 2014.

Conclusion

The analysis of epidemiological data is essential to better evaluate the evolution of the urolithiasis disease, which was affirmed in our study, where a constant evolution of the characteristics of the disease was revealed, testifying the change of the socio-economic level in Algeria.

Lactiplantibacillus plantarum Reduced Renal Calcium Oxalate Stones by Regulating Arginine Metabolism in Gut Microbiota

Renal calcium oxalate (CaOx) stones are a common kidney disease. There are few methods for reducing the formation of these stones. However, the potential of probiotics for reducing renal stones has received increasing interest. We previously isolated a strain of Lactiplantibacillus plantarum N-1 from traditional cheese in China. This study aimed to investigate the effects of N-1 on renal CaOx crystal deposition. Thirty rats were randomly allocated to three groups: control group (ddH2O by gavage), model group [ddH2O by gavage and 1% ethylene glycol (EG) in drinking water], and Lactiplantibacillus group (N-1 by gavage and 1% EG in drinking water). After 4 weeks, compared with the model group, the group treated with N-1 exhibited significantly reduced renal crystals (P < 0.05). In the ileum and caecum, the relative abundances of Lactobacillus and Eubacterium ventriosum were higher in the control group, and those of Ruminococcaceae UCG 007 and Rikenellaceae RC9 were higher in the N-1-supplemented group. In contrast, the relative abundances of Staphylococcus, Corynebacterium 1, Jeotgalicoccus, Psychrobacter, and Aerococcus were higher in the model group. We also predicted that the arginase level would be higher in the ileal microbiota of the model group than in the N-1-supplemented group with PICRUSt2. The arginase activity was higher, while the level of arginine was lower in the ileal contents of the model group than in the N-1-supplemented group. The arginine level in the blood was also higher in the N-1-supplemented group than in the model group. In vitro studies showed that exposure to arginine could reduce CaOx crystal adhesion to renal epithelial HK-2 cells. Our findings highlighted the important role of N-1 in reducing renal CaOx crystals by regulating arginine metabolism in the gut microbiota. Probiotics containing L. plantarum N-1 may be potential therapies for preventing renal CaOx stones.

Stone composition of renal stone formers from different global regions

OBJECTIVE

To study urinary stone composition patterns in different populations around the world.

MATERIALS AND METHODS

Data were collected by reviewing charts of 1204 adult patients of 10 countries with renal or ureteral stones (> 18 years) in whom a stone analysis was done and available. Any method of stone analysis was accepted, but the methodology had to be registered.

RESULTS

In total, we observed 710 (59%) patients with calcium oxalate, 31 (1%) with calcium phosphate, 161 (13%) with mixed calcium oxalate/calcium phosphate, 15 (1%) with carbapatite, 110 (9%) with uric acid, 7 (< 1%) with urate (ammonium or sodium), 100 (9%) with mixed with uric acid/ calcium oxalate, 56 (5%) with struvite and 14 (1%) with cystine stones. Calciumcontaining stones were the most common in all countries ranging from 43 to 91%. Oxalate stones were more common than phosphate or mixed phosphate/oxalate stones in most countries except Egypt and India. The rate of uric acid containing stones ranged from 4 to 34%, being higher in Egypt, India, Pakistan, Iraq, Poland and Bulgaria. Struvite stones occurred in less than 5% in all countries except India (23%) and Pakistan (16%). Cystine stones occurred in 1% of cases.

CONCLUSIONS

The frequency of different types of urinary stones varies from country to country. Calcium-containing stones are prevalent in all countries. The frequency of uric acid containing stones seems to depend mainly on climatic factors, being higher in countries with desert or tropical climates. Dietary patterns can also lead to an increase in the frequency of uric acid containing stones in association with high obesity rates. Struvite stones are decreasing in most countries due to improved health conditions.

Trends in urinary stone composition in 23,182 stone analyses from 2011 to 2019: a high-volume center study in China

PURPOSE

To evaluate the distribution and dynamic trends in constituents of urinary stones in China.

MATERIALS AND METHODS

The composition of 23,182 stones were analyzed and then recorded between January 2011 and December 2019. The characteristics in terms of stone patient's gender, age and calendar year were analyzed.

RESULTS

Most stones (22,172, 95.64%) had several crystal components, among which 40.25% (8925/22,172) were mixtures with infection components. Calcium oxalate (CaOx) and uric acid (UA) stones were more commonly encountered in men, but calcium phosphate (CaP), magnesium ammonium phosphate (MAP) and carbonate apatite (CA) stones were more prevalent in women (p < 0.05). In males, the proportion of CaOx stones increased up to the age of 40, but subsequently decreased (p < 0.001). Interestingly, females showed an inverse trend regarding CaOx stones (p < 0.001). The proportion of UA stones increased with age (p < 0.001), and CA stones most frequently were recorded at age 20-49. Over the past 9 years, UA, CA, and MAP stones increased over time, whereas there was a tendency for CaOx stones to decrease (p < 0.05).

CONCLUSIONS

The scarcity of pure stones and a certain proportion of mixtures with infection stone components (e.g., mixtures of CaOx and CA) suggest that treatment directed against a single stone component is insufficient for effective recurrence prevention. Age and gender were significant determinants of stone composition, and according to the observed chronological trends, it seems that in the future, more UA, CA and MAP stones and fewer CaOx stones may be encountered in the studied population.

Meta-analysis of Clinical Microbiome Studies in Urolithiasis Reveal Age, Stone Composition, and Study Location as the Predominant Factors in Urolithiasis-Associated Microbiome Composition

To determine whether functionally relevant questions associated with the urinary or gut microbiome and urinary stone disease (USD) can be answered from metagenome-wide association studies (MWAS), we performed the most comprehensive meta-analysis of published clinical MWAS in USD to date, using publicly available data published prior to April 2021. Six relevant studies met inclusion criteria. For alpha-diversity, significant differences were noted between USD status, stone composition, sample type, study location, age, diet, and sex. For beta-diversity, significant differences were noted by USD status, stone composition, sample type, study location, antibiotic use (30 days and 12 months before sampling), sex, hypertension, water intake, body habitus, and age. Prevotella and Lactobacillus in the gut and urinary tract, respectively, were associated with healthy individuals, while Enterobacteriaceae was associated with USD in the urine and stones. Paradoxically, other Prevotella strains were also strongly associated with USD in the gut microbiome. When data were analyzed together, USD status, stone composition, age group, and study location were the predominant factors associated with microbiome composition. Meta-analysis showed significant microbiome differences based on USD status, stone composition, age group or study location. However, analyses were limited by a lack of public data from published studies, metadata collected, and differing study protocols. Results highlight the need for field-specific standardization of experimental protocols in terms of sample collection procedures and the anatomical niches to assess, as well as in defining clinically relevant metadata and subphenotypes such as stone composition.

Exploring mechanisms of protein influence on calcium oxalate kidney stone formation

Calcium oxalate monohydrate (COM) crystals are the primary constituent of most kidney stones, but urine proteins in stone matrix are believed to be critical elements for stone formation from these crystals. Recent data have shown that hundreds of proteins appear in the stone matrix with no explanation for inclusion of so many proteins. We have proposed a stone formation model with protein stimulated COM aggregation based on polyanion-polycation aggregation, which is supported by finding that matrix is highly enriched in strongly anionic and strongly cationic proteins. Many other proteins may be drawn to such aggregates due to their limited solubility in water or charge effects. Finding similar protein enrichment in both polyarginine (pR) induced aggregates of urine proteins and COM stone matrix would support this hypothesis. Purified proteins (PP) were obtained from random urine samples of six healthy adults by ultradiafiltration. Protein aggregation was induced by adding pR to PP solutions at two concentrations; 0.25 and 0.5 µg pR/µg of PP. Samples of each fraction and the original PP mixture were lyophilized and analyzed by tandem mass spectrometry. Aggregates induced by pR addition to PP samples collected a protein mixture that mimicked the protein distribution observed in COM matrix, supporting our hypothesis. The apparently discordant behavior of certain abundant anionic proteins preferentially joining the pR aggregate, when they had demonstrated reduced abundance in COM stone matrix, suggests that this model was overdriven to aggregate. The reversal of aggregate preference of albumin at low pR addition supports this interpretation.

[Chemical composition of urinary stones and associated factors in the Democratic Republic of Congo]

To compare the chemical composition of the upper and lower urinary tract stones in Congolese patients, and to identify factors associated with the different types of stones. Stones from 119 patients originating from the upper tract and 75 from the lower tract were analyzed by infrared spectrophotometry. Among 119 patients with upper tract stones, age ranged from 10 to 81 years with a mean (SD) of 45.8 (13.6) years; males were the majority (55.5%). The main types of stones identified were whewellite (79%). For the 75 patients with lower apparatus stones, age ranged from 4 to 87 years with a mean (SD) of 51.6 (21.6) years; the majority were males (89.3%). The main types of stones were whewellite (44%) and anhydrous uric acid (22.7%). Overall, the factors associated with calcium oxalate included: site [4.95 (95% CI 2.35-10.44)] and diameter [3.03 (95% CI 1.45-6.25)]; patient's place of residence [0.05 (95% CI 0.01-0.29)] was associated with calcium phosphate. Infection stones were associated with; site [0.19 (95% CI 0.06-0.63)] and diameter [0.10 (95% CI 0.03-0.38)]. Finally, age 0.26 (95% CI 0.09-0.71) and stone site [0.23 (95% CI 0.07-0.68)] were associated with uric stones. The epidemiological and chemical profile of upper and lower tract stones were different. Several factors were associated with the chemical and crystalline composition of stones in the Democratic Republic of Congo.

The stone crescent of Anatolia

OBJECTIVES

To assess the largest stone composition data available and to present the variations in the stone composition according to gender and different climatic environments in Turkey.

METHODOLOGY

Data for a total of 24 768 urinary stone patients from the Turkish Mineral Research and Exploration Institute were evaluated. X-ray diffraction crystallography was used for analysis and the Köppen-Trewartha classification was used to assess the climatic features of the cities. After the assessment, the cities were divided into two groups-those with a continental climate (Dc) were defined as inland areas and the others (Non-Dc) were defined as coastal areas.

RESULTS

The male-to-female ratio was 2.2:1. Amongst the patients, 53.7% had pure stones, while 46.3% had mixed-type stones. The most common type of stone was calcium oxalate in both pure and mixed stone groups. Given the climate patterns, the stone ratio between regions with a Dc climate and a Non-Dc climate was approximately 2:3. Cystine and uric acid stones were observed more frequently in inland regions, while calcium oxalate, whewellite, and struvite stones were observed more frequently in coastal areas (P = .005, P < .001, P < .001, P = .002, P = .002, respectively). Calcium oxalate stones were found at a higher rate in men, while cysteine, struvite, and calcium phosphate stones were more common in women (P < .001, P = .003, P < .001, P < .001, respectively).

CONCLUSION

This study provides the most comprehensive data on the stone disease in Turkey. Considering the distribution of stone disease in Turkey, the frequency of analysed stones had parallels with the temperature averages and climate features, presenting crescent-like distribution.

Metabolic and Clinical Characteristics of Children with Urolithiasis from Southern India

OBJECTIVE

To study the etiological profile and patterns of clinical presentations of urolithiasis (UL) in children.

METHODS

This observational study included patients <18 y with UL, who were referred to the pediatric nephrology clinic. Clinical features, family history, consanguinity and estimated glomerular filtration rate (eGFR) at presentation and follow-up were recorded. The children were evaluated using relevant blood and urine investigations.

RESULTS

A total of 72 children with UL were evaluated for the study. The etiology of UL (n = 72) included hyperoxaluria (n = 25; 34.7%), idiopathic hypercalciuria (n = 21; 29.2%), idiopathic hyperuricosuria (n = 3; 4.2%), cystinuria (n = 3; 4.2%), urate transporter defect (n = 2; 2.8%) and mixed stones (predominant component calcium oxalate) (n = 9; 12.5%). No etiology was detected in 4 cases (5.5%). Common presenting complaints included flank pain (n = 41; 56.7%), hematuria (n = 29; 40.3%), urinary tract infection (UTI) (n = 29; 40.3%) and vomiting (n = 11; 15.3%). The median age of presentation was 60 (36, 96) mo. Family history and consanguinity were present in 30 cases (41.7%) and 28 cases (38.9%) respectively. Stone analysis was done in 20 cases, of which 9 cases were mixed stones (predominant calcium oxalate) and 6 were calcium oxalate stones.

CONCLUSIONS

Among children with urolithiasis, hyperoxaluria, idiopathic hypercalciuria, idiopathic hyperuricosuria, and cystinuria were the predominant identifiable entities, together accounting for 72% of cases; and renal colic, hematuria and UTI were the commonest clinical complaints.

Urinary stone composition analysis and clinical characterization of 1520 patients in central China

A total of 1520 patients with urinary stones from central China were collected and analysed by Fourier transform infrared spectroscopy between October 1, 2016 and December 31, 2019. For all patients, age, sex, comorbidities, stone location, laboratory examination and geographic region were collected. The most common stone component was calcium oxalate (77.5%), followed by calcium phosphate (8.7%), infection stone (7.6%), uric acid (UA) stone (5.3%)and cystine (0.9%). The males had more calcium oxalate stones (p < 0.001), while infection stone and cystine stones occurred more frequently in females (p < 0.001). The prevalence peak occurred at 41-60 years in both men and women. UA stones occurred frequently in patients with lower urinary pH (p < 0.001), while neutral urine or alkaline urine (p < 0.001) and urinary infection (p < 0.001) were more likely to be associated with infection stone stones. Patients with high levels of serum creatinine were more likely to develop UA stones (p < 0.001). The proportion of UA stones in diabetics was higher (p < 0.001), and the incidence of hypertension was higher in patients with UA stones (p < 0.001). Compared to the other types, more calcium oxalate stones were detected in the kidneys and ureters (p < 0.001), whereas struvite stones were more frequently observed in the lower urinary tract (p = 0.001). There was no significant difference in stone composition across the Qinling-Huaihe line in central China except UA stones, which were more frequently observed in patients south of the line (p < 0.001).