Epidemiology, Pathogenesis, and Pathophysiology of Urolithiasis

Kidney computed tomography perfusion in patients with ureteral obstruction

INTRODUCTION

Kidney perfusion on CT is an encouraging surrogate for renal scintigraphy in assessing renal function. However, data on dynamic volumetric CT in patients with kidney obstruction is lacking. Thus, the aim of this study is to determine the feasibility of CT-based renal perfusion using a dynamic volume to assess renal hemodynamics at different degrees and durations of obstruction.

MATERIALS AND METHODS

We included patients with unilateral kidney obstruction in our single-center, prospective study. The patients were divided into three groups. Patients without dilatation of the pelvicalyceal system (PCS) and normal parenchyma thickness were included into Group 1; patients with PCS dilatation and parenchyma thickness 1.8-2.4 cm-into Group 2; and patients with ureteropyelocalicoectasia and parenchyma thickness less than 1.8 cm-into Group 3.

RESULTS

Total of 56 patients were enrolled. In Group 1 mean values of cortical and medullar arterial blood flow, blood volume, and extraction fraction were within the normal range. Changes in contralateral kidney were not determined. Patients from Group 2 showed significant differences in blood flow parameters in the cortical and medulla of the obstructed kidney. No changes in perfusion values in the contralateral kidney was observed. In patients from Group 3 there was a marked decrease in perfusion on the side of obstruction compared to Group 2, indicating that the degree of expansion of the PCS directly correlates with the change in blood flow. However, in the contralateral kidney, these indicators exceeded the normal values of perfusion.

CONCLUSION

CT perfusion allows to objectively assess changes in blood flow in the setting of renal obstruction. The degree of obstruction directly affects the measured rate of blood flow.

In silico docking and Molecular Dynamic (MD) simulations studies of selected phytochemicals against Human Glycolate Oxidase (hGOX) and Oxalate oxidase (OxO)

Globally, Urolithiasis is the most prevalent urological problem which affects the populations across the ages and races. In recent years, several phytochemicals are being investigated to improve the efficacy and safety of anti-urolithiasis formulations. To develop drugs based on traditional medicines, it is essential to understand the molecular mechanism of action of these drugs. We present the results of in silico docking and molecular dynamic (MD) simulation studies on selected phytochemical including catechin, epicatechin, gallic acid, gallocatechin, epigallocatechin, epigallocatechin 3-o-gallate, 4-methoxy-nor-securine, nor-securinine, and fisetin with human glycolate oxidase (hGOX) and oxalate oxidase (OxO). Gallic acid, gallocatechin and fisetin showed better docking scores than the rest. In MD simulation analysis, stable interactions of the gallic acid with hGOX and OxO; gallocatechin and fisetin with hGOX were observed. It was found that, gallic acid stably interacts withTYR26, LYS 236, ARG 315, and ASP 291 residues of hGOX. On other hand, gallic acid stably interacs with GLU 58 residue of OxO. Gallocatechin, forms stable interactions with TYR 26, ASP 170, ARG 167 and THR 161 of HGOX. In MD simulations, fisetin stably interacted with TYR 26, TRP110 and ARG 263 as we predicted in molecular docking. None of the interactions was formed during the MD simulation of OxO with gallocatechin and fisetin. Together, these results suggest that gallic acid, gallocatechin and fisetin are the potential candidates for the development of phytochemicals for the management of urolithiasis in humans.

Comparison of two software programs used to determine the relative supersaturation of urine ions

Introduction

Relative supersaturation (RSS) values for urine crystals are a measure of the risk of urinary stone formation and have been shown to be lowered in foods shown to aid in the management of urolithiasis. In order to calculate RSS in pets, computer programs have been developed to calculate RSS and aid in the understanding of stone formation in veterinary medicine. However, some older programs have not been updated for use in animals, and the specific coefficients used are not publically available. One of the first RSS programs was developed in BASIC computer language and published in 1985 which was called EQUIL2. The EQUIL2 program was updated to a compiled version compatible with a PC platform. However, the formulas could not be read or altered.

Methods

This study evaluates a new program with known coefficients to the original EQUIL2 program. The RSS values of the two programs were compared through a t-test, calculating the r² from correlation analysis, Lin's concordance correlation coefficient, and by a Bland-Altman analysis of outputs from the two programs using urine samples from healthy dogs and cats.

Results and Discussion

Our results show that for both magnesium ammonium phosphate (struvite) and calcium oxalate, the RSS values of the original program could be calculated from the new programs RSS values. Although the actual RSS values were different (as might be expected through the use of the updated coefficients and different thermodynamic stability constants in the calculations) the results were highly correlated, finding elevations and reductions in RSS proportionally in the same urine samples. The current work creates a foundation for using the modernized program to calculate RSS and provides a shared method for understanding the risk of struvite and calcium oxalate stone formation.

Dietary supplements and medicinal plants in urolithiasis: diet, prevention, and cure

BACKGROUND

Urolithiasis has been a major health concern for centuries, primarily owing to the limited treatment options in the physician's armamentarium. However, various studies have underscored a lesser incidence of urolithiasis in cohorts predominantly consuming fruits and vegetables. This article aims to review various dietary plants, medicinal herbs and phytochemicals in the prevention and management of urolithiasis.

METHODS

To provide context and evidence, relevant publications were identified on Google Scholar, PubMed and Science-Direct using keywords such as urolithiasis, nephrolithiasis, urolithiasis, renal stones, phytochemicals and dietary plants.

RESULTS

Growing bodies of evidence suggest the incorporation of plant-based foods, medicinal and herbal supplements, and crude drugs containing phytochemicals into the staple diet of people. The anti-urolithiatic activity of these plant bioactives can be attributed to their antioxidant, antispasmodic, diuretic, and inhibitory effect on the crystallization, nucleation and crystal aggregation effects. These mechanisms would help alleviate the events and symptoms that aid in the development and progression of renal calculi. In addition, it will also avoid the exacerbation of secondary disorders like inflammation and injury, which can initiate a vicious circle in turn worsening the disease progression.

CONCLUSION

In conclusion, the results presented in the review demonstrate the promising role of various dietary plants, medicinal and herbal supplements, and phytochemicals in preventing and managing the precipitation of uroliths. However, more conclusive and cogent evidence from preclinical and clinical studies is required to substantiate their safety, efficacy and toxicity profiles in humans.

Mineralogy, geochemistry, and micromorphology of human kidney stones (urolithiasis) from Mersin, the southern Turkey

This study describes the primary characteristics of the selected kidney stones surgically removed from the patients at the Mersin University Hospital in the southern Turkey and interprets their formation via petrographic, geochemical, XRD, SEM-EDX, and ICP-MS/OES analyses. The analytical results revealed that the kidney stones are composed of the minerals whewellite, struvite, hydroxyapatite, and uric acid alone or in different combinations. The samples occur in staghorn, bean-shaped composite, and individual rounded particle shapes, which are controlled by the shape of the nucleus and the site of stone formation. The cross-section of the samples shows concentric growth layers due to variations in saturation, characterizing the metastable phase. Kidney stone formation includes two main stages: (i) nucleation and (ii) aggregation and/or growth. Nucleation was either Randall plaque of hydroxyapatite in tissue on the surface of the papilla or a coating of whewellite on the plaque, or crystallization as free particles in the urine. Subsequently, aggregation or growth occurs by precipitation of stone-forming materials around the plaque or coating carried into the urine, or around the nucleus formed in situ in the urine. Urinary supersaturation is the main driving force of crystallization processes; and is controlled by many factors including bacterially induced supersaturation.

Experimental Observation of Isolative Efficacy of a Solid Coupling Medium in Extracorporeal Shock Wave Lithotripsy—Implications to Nosocomial Infection Prevention

Introduction: Extracorporeal shock wave lithotripsy (ESWL) is a well-established, popular treatment choice for renal stones. Traditionally, the semi-liquid gel is used as a coupling medium in ESWL. During ESWL, body fluid or blood might transmit between the patients when the probe or gel used in the procedure is contaminated and cause potential nosocomial infections. To solve this problem, we developed a solid coupling medium (isolation coupling pad, referred to as “icPad”) between the patient’s skin and the probe as a shock wave transmission medium to prevent contamination. This study aimed to investigate the isolative efficacy of the icPad in blocking the permeation of microbes. Method: Rhodamine 6G (a fluorescent dye) was used as a tracer to simulate the microorganisms. The penetration of the fluorescent dye on the longitudinal section of the icPad was observed by a microscope after the dye was placed on the body side of the icPad for 40 min. After the shock wave, icPad was extracted with 75% ethanol, and fluorescence intensity was measured with a fluorescence spectrometer. Results: Our results revealed that the body side of icPad is free of fluorescent dye during lithotripsy. Qualitative analysis results confirmed that icPad has an isolative effect on simulating contaminants such as bacteria or viruses. Conclusion: In this in vitro phantom study, a proprietary icPad can be an isolative coupling medium and is speculated to avoid cross-contamination of bacterial or viral infection during ESWL.

Stone disease in low-middle income countries. Could augmented reality have a role in its management?

Urolithiasis is a global phenomenon. Cystolithiasis is common in parts of Africa due to low protein intake and dehydration from endemic diarrhoeal illnesses. Nephrolithiasis is less prevalent than in high income countries, probably due to a variety of lifestyle issues, such as a more elemental diet, higher physical activity and less obesity. Although renal stones are less common in low-middle income countries (LMICs), the social and economic impacts of nephrolithiasis are still considerable; many stones present late or with complications such as upper urinary tract obstruction or urosepsis. These may lead to the development of chronic kidney disease, or end-stage renal failure in a small proportion of cases, conditions for which there is very poor provision in most LMICs. Early treatment of nephrolithiasis by the least invasive method possible can, however, reduce the functional consequences of urinary stone disease. Although ESWL is uncommon, and endoscopic interventions for stone are not widespread in most of Africa, percutaneous nephrolithomy and ureteroscopic renal surgery are viable techniques in those regional centres with infrastructure to support them. Longitudinal mentoring has been shown to be a key step in the adoption of these minimally invasive procedures by local surgeons, something that has been difficult during the COVID-19 pandemic due to travel restriction. Augmented reality (AR) technology is an alternative means of providing remote mentoring, something that has been trialled by Urolink, the MediTech Trust and other global non-governmental organisations during this period. Our preliminary experience suggests that this is a viable technique for promulgating skills in LMICs where appropriate connectivity exists to support remote communication. AR may also have long term promise for decreasing the reliance upon short-term surgical visits to consolidate competence, thereby reducing the carbon footprint of global surgical education.

Role of Multi-Detector Computed Tomography Indices in Predicting Extracorporeal Shockwave Lithotripsy Outcome in Patients With Nephrolithiasis

Background

Nephrolithiasis is one of the most common renal pathologies and is routinely encountered in daily practice. Non-contrast computed tomography (NCCT) is the gold standard diagnostic imaging modality for urolithiasis. The role of HU (Hounsfield units) in calculus as a predictor of extracorporeal shock wave lithotripsy (ESWL) has been studied in the past. This study aims to evaluate the role of HU value and various other NCCT indices in predicting the outcome of ESWL.

Material and methods

This was a prospective observational study that included 45 patients suffering from nephrolithiasis who underwent NCCT-KUB (kidney, ureter, and bladder) followed by ESWL. The NCCT indices were evaluated and correlated with the outcome of ESWL. NCCT-KUB was performed using multidetector SIEMENS® SOMATOM EMOTION 16-slice CT scanner (SIEMENS, Munich, Germany).

Results

In our study, the HU value turned out to be a statistically significant predictor of ESWL success (p <0.05), and the renal pelvis also proved to be a good prognostic indicator for ESWL success. The cut-off value of <1179 HU favored a successful outcome of ESWL, while if >1179 HU, ESWL is likely to fail. Hence, the successful outcome of ESWL is inversely proportional to the HU value. Renal pelvic calculi (n=14) showed a 100% success rate, which was better than all other calculus locations (p<0.05). However, the rest of the indices did not show any statistical significance.

Conclusion

Multi-detector NCCT-KUB indices can help in the selection of patients with a good prognosis for ESWL, which will prevent the patient from undergoing undesired invasive procedures.

Ethnomedicinal Plants Used for Treatment of Urolithiasis in India: A Review

Background:

The kidney stone is the most commonly observed and painful disease of the urinary tract in human being. Numerous intrinsic and extrinsic factors are responsible for the formation of kidney stone, for instance, age, sex, heredity (intrinsic factors) and climate, dietary, geography, mineral composition, and water intake (extrinsic factors). The kidney stones are categorized into calcium, struvite or magnesium ammonium phosphate, uric acid or urate, cystine and other types of stones based on chemical composition and pathogenesis. Due to the multifactorial nature of kidney stone disease, the patient may need to rely on complex synthetic medication. However, in ancient Indian history, there are several pieces of evidence where natural resources such as plants were used to remediation this lethal disease.

Objective:

The present review attempts to provide exhaustive information of ethnomedicinal and ethnopharmacological information of medicinal plants used for kidney stone in India.

Result:

Hitherto, there are a total of 258 ethnomedicinal plants from 90 different families reported using for kidney stone application. The majority of the plant species are associated with three important families: Asteraceae, Amaranthaceae, and Fabaceae. Most of the plants are from Andhra Pradesh (43 plants), followed by East Bengal (38), Jammu & Kashmir (36), Uttarakhand (31), Panjab (27), Mizoram (23), Karnataka (20), Maharashtra (20) and Assam (18). The commonly used plant parts for the herbal preparation are roots (21.22 %) followed by leaves/leaf (20.15 %), and sometimes complete plant (17.77 %) is used. The most commonly used method for the formulation is decoction (46.41 %) followed by powder (18.66 %) and then extracts (15.78 %) of different aerial and non-aerial parts of the plant. To date, the in-vitro and in-vivo activities against the kidney stone assessed for more than sixty ethnomedicinal plants.

Conclusion:

The present review epitomizes the ethnomedicinal information of medicinal plants used for kidney stone and pharmacological evidence for anti-urolithiasis activity. Most reported medicinal plants are not yet scientifically explored and need immediate attention before we lose some important species due to excessive deforestation for farming and industrial needs.

Global Trends in Incidence and Burden of Urolithiasis from 1990 to 2019: An Analysis of Global Burden of Disease Study Data

Background

Urolithiasis is among the most common urologic diagnoses globally, with substantial burden and cost on healthcare systems worldwide. Increasing evidence links urolithiasis with an array of risk factors, including diet and lifestyle trends, noncommunicable diseases such as diabetes and obesity, and global warming.

Objective

To examine geographic, temporal, and sociodemographic patterns to better understand global disease burden of urolithiasis.

Design, setting, and participants

We extracted data on age-standardized incidence rate (ASIR), deaths, and disability-adjusted life years (DALYs) attributed to urolithiasis for 21 regions, including 204 countries, for 1990–2019 from the Global Burden of Disease (GBD) study.

Outcome measurements and statistical analysis

Data were analyzed at the global, regional, and country levels, as well as stratified by the Socio-Demographic Index. The average annual percentage change (AAPC) was calculated to measure temporal trends across groups.

Results and limitations

Globally, total cases, DALYs, and deaths attributed to urolithiasis increased over the study period, while the age-standardized rates of these measures decreased. The age-standardized incidence of urolithiasis decreased from 1696.2 (95% confidence interval [CI] 1358.1–2078.1) cases per 100 000 population in 1990 to 1394.0 (95% CI, 1126.4–1688.2) cases per 100 000 population in 2019, with an AAPC of −0.7 (95% CI [−0.8, −0.6]). Of the GBD regions, Eastern Europe demonstrated a consistently higher ASIR of urolithiasis than all other regions, while the Caribbean had the highest AAPC. This study is limited by the available national and regional data, as described in the original GBD study.

Conclusions

Worldwide, total cases, DALYs, and deaths attributed to urolithiasis have increased since 1990, while age-standardized rates have decreased, with demonstrated regional and sociodemographic variation. Multifaceted strategies to address urolithiasis prevention and treatment are necessary.

Patient summary

In this study, we looked at trends in the global burden of stone disease using data from 204 countries from 1990 to 2019. We found that the overall burden has increased, but it varies by age, sociodemographic variables, and geographic region. We conclude that we need adaptable policies that suit the specific needs of the country to address this burden.

Mineralogy, geochemistry, 13C and 16O isotopic characteristics of urinary stones in Iran, a case study of Lorestan Province

Owing to the importance of urinary stones as one of the biominerals in the human body, it is necessary to investigate their chemical composition and mineralogy. In this matter, a mineralogical study using X-ray diffraction and scanning electron microscopy indicated that urinary stones in Lorestan Province were divided into 5 groups of calcium oxalate, urate, cysteine, phosphate and mixed stones (Whewellite, uric acid, phosphate). In this regard, the microscopic studies revealed that Whewellite was the most important mineral phase among various phases. In the following, the major and rare elements of each group were determined by inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence analysis. The obtained results demonstrated that Ca was found the most abundant element in urinary stones. In the analysis results of the major oxides, compared to other major oxides, CaO had the highest frequency in urinary stones. The reason was due to the role of calcium in most of the basic functions in cell metabolism. The average values of isotope ¹³C and ¹⁶O in the studied urinary stones were obtained - 33.71 and - 20.57, respectively. Overall, the values of ¹³C isotope in urinary stones were lower than those in the similar stones and human hard tissues in other countries.

Doppler-Assessed Ureteric Jet Frequency: A Valuable Predictor of Ureteric Obstruction

Objectives: To compare ureterovesical jet frequency in non-obstructed versus obstructed ureter secondary to ureteric stone using ultrasonography in patients presenting with ureteral stones.

Study design: Cross-sectional prospective study.

Place of study and duration: Urology Department, The Kidney Centre Post Graduate Training Institute from May 16 to November 15, 2019.

Methods: This study included 97 patients having presented in the emergency department with acute renal colic and were diagnosed as having ureteral stones on a non-contrast-enhanced computed tomography (NCCT). The ureteric jet frequency was measured by Doppler ultrasonography by our radiologist with the Hitachi Aloka F-37 ultrasound machine after they underwent CT. Patients were asked to drink 750-1000 ml of liquids 15-20 minutes before their ultrasonographic examination of both kidneys, ureters, and urinary bladder. The kidney size (length and width) and presence/absence of hydronephrosis were evaluated by grayscale ultrasound. Then, with the help of color Doppler ultrasonography, the frequency of the ureteric jet was recorded.

Results: The patient's mean age was 46.66 ± 3.21 years ranging from 37 to 56 years. There were 58 (59.8%) male and 39 (40.2%) female cases. The mean cumulative stone size was 9.77 ± 2.65 mm. According to stone location, 44 (45.4%) cases had upper ureteric, 24 (24.7%) cases had mid ureteric, and 29 (29.9%) cases had lower ureteric stone. The mean obstructive side jet frequency was 0.70/min ± 0.49, and the non-obstructive side jet frequency was 2.89/min ± 1.29 (P < 0.05).

Conclusions: The mean obstructive side jet frequency was 0.70 ± 0.49/min, which, if we compare to the non-obstructed normal ureter, is significantly less. Hence, color Doppler ultrasonography can be helpful to patients who were previously diagnosed with ureteral stones on NCCT to see if their stone has passed. This can be a very cost-effective modality especially in resource-poor countries where repeat CT can be very expensive. The results from this study can also be used in a specific population (i.e., pregnancy) where the use of imaging modalities that involve ionizing radiation is prohibited.

Comparison of the Efficacy of Male Sexual Activity Versus Alpha-Blockers in the Expulsion of Distal Ureteric Stones: A Systematic Review and Meta-Analysis

Globally, the prevalence of urolithiasis is increasing, with limited effective treatment options. Though debate exists within the literature, the use of medical expulsive therapy (MET) for distal ureteric stones in the form of alpha-blockers is commonplace. Alpha-blockers work via the inhibition of norepinephrine, resulting in a small degree of distal ureteric relaxation. Nitric oxide (NO), the main neurotransmitter involved in penile erection, causes smooth muscle relaxation of the distal ureter. It is hypothesised that these alternative pathways may achieve the same desire clinical effect. To our knowledge, this is the first meta-analysis comparing the efficacy of male sexual activity, in the form of intercourse or masturbation, to alpha-blockers in the expulsion of ureteric stones. We conducted a comprehensive search of electronic databases (PubMed, MEDLINE, EMBASE, SCOPUS, CENTRAL and Google Scholar), identifying studies comparing male sexual activity versus alpha-blockers, in male patients with distal ureteric stones. The Cochrane risk-of-bias tool was used to assess the included studies. For data analysis, a random effects model was used in the event of significant heterogeneity (>75%), with fixed-effects modelling in the event of low-moderate heterogeneity. A search of electronic databases found three randomised control trials (RCTs), enrolling a total of 262 patients. There was no statistically significant difference observed when patients engaged in sexual activity rather than alpha-blocker, when looking at stone expulsion rate at two weeks (P=0.36), expulsion rate at four weeks (P=0.57), or the mean stone expulsion time (P=0.21). Furthermore, there was no significant difference observed when looking at analgesic requirements (P=0.43), or the requirement for additional procedures (P=0.57). Our meta-analysis demonstrated that male sexual activity as an alternative therapy for distal ureteric stones had comparable outcomes to the use of alpha-blocker, proving a viable alternative therapy in those patients wishing to avoid pharmacological management.

Evaluating outcomes of complete supine percutaneous nephrolithotomy for staghorn vs multiple non-staghorn renal stones: a 10-year study

PURPOSE

To evaluate the outcomes of complete supine percutaneous nephrolithotomy (csPCNL) for staghorn stones and multiple large non-staghorn stones.

METHODS

The records of 886 patients who underwent csPCNL from September 2009 to October 2019 were considered. Out of them, 201 cases met the eligibility criteria and they were divided into three groups: 63 cases of staghorn, 68 cases of multiple medium (20 mm < diameter ≤ 30 mm) non-staghorn and 70 cases of multiple large non-staghorn (> 30 mm) stones. Almost all outcomes and stone-related factors were analyzed.

RESULTS

There was not any significant difference regarding age, body mass index, history of urinary tract infection, transfusion rate, complication rate, pre and post-surgery serum creatinine, hemoglobin drop and total hospital stay between the three groups. Stone free rate was 98.5% in multiple medium group, 97.1% in multiple large group and 84.1% in staghorn group (P = 0.001). The operation duration was significantly shorter for the multiple medium group (P < 0.001) but it was not significantly different between the multiple large non-staghorn and staghorn group.

CONCLUSION

The results demonstrated that almost all outcomes were not significantly different between the three groups (especially between staghorn and larger non-staghorn ones). These findings reveal that surgeons could choose csPCNL for treatment of staghorn stones and multiple large non-staghorn stones and consider staghorn stones as challenging as multiple large (especially diameter > 30 mm) non-staghorn stones.

In Search of an Efficient Complexing Agent for Oxalates and Phosphates: A Quantum Chemical Study

Limiting gastrointestinal oxalate absorption is a promising approach to reduce urinary oxalate excretion in patients with idiopathic and enteric hyperoxaluria. Phosphate binders, that inhibit gastrointestinal absorption of dietary phosphate by the formation of easily excretable insoluble complexes, are commonly used as a treatment for hyperphosphatemia in patients with end-stage renal disease. Several of these commercially available phosphate binders also have affinity for oxalate. In this work, a series of metallic cations (Li⁺, Na⁺, Mg²⁺, Ca²⁺, Fe²⁺, Cu²⁺, Zn²⁺, Al³⁺, Fe³⁺ and La³⁺) is investigated on their binding affinity to phosphate and oxalate on one side and anionic species that could be used to administer the cationic species to the body on the other, e.g., acetate, carbonate, chloride, citrate, formate, hydroxide and sulphate. Through quantum chemical calculations, the aim is to understand the competition between the different complexes and propose possible new and more efficient phosphate and oxalate binders.

Human kidney stones: a natural record of universal biomineralization

GeoBioMed - a new transdisciplinary approach that integrates the fields of geology, biology and medicine - reveals that kidney stones composed of calcium-rich minerals precipitate from a continuum of repeated events of crystallization, dissolution and recrystallization that result from the same fundamental natural processes that have governed billions of years of biomineralization on Earth. This contextual change in our understanding of renal stone formation opens fundamentally new avenues of human kidney stone investigation that include analyses of crystalline structure and stratigraphy, diagenetic phase transitions, and paragenetic sequences across broad length scales from hundreds of nanometres to centimetres (five Powers of 10). This paradigm shift has also enabled the development of a new kidney stone classification scheme according to thermodynamic energetics and crystalline architecture. Evidence suggests that ≥50% of the total volume of individual stones have undergone repeated in vivo dissolution and recrystallization. Amorphous calcium phosphate and hydroxyapatite spherules coalesce to form planar concentric zoning and sector zones that indicate disequilibrium precipitation. In addition, calcium oxalate dihydrate and calcium oxalate monohydrate crystal aggregates exhibit high-frequency organic-matter-rich and mineral-rich nanolayering that is orders of magnitude higher than layering observed in analogous coral reef, Roman aqueduct, cave, deep subsurface and hot-spring deposits. This higher frequency nanolayering represents the unique microenvironment of the kidney in which potent crystallization promoters and inhibitors are working in opposition. These GeoBioMed insights identify previously unexplored strategies for development and testing of new clinical therapies for the prevention and treatment of kidney stones.

Antilithiatic activity of a non-pharmacopoeial Unani formulation in chemically induced urolithiasis in rats

OBJECTIVES

Parshioshan (Adiantum capillus-veneris L.), Duqu (Peucedanum grande C.B. Clarke), Kaknaj (Physalis alkekengi L.) and Kharekhasak (Tribulus terresteris L.) have been selected for this study as they have been associated with medicinal actions for litholytic activity.

METHODS

The experiment was carried out in Sprague Dawley rats divided into seven groups, serving as plain control, disease control, standard control, curative A and B and preventive A and B groups. Animals of plain control received distilled water. Remaining six groups received Ethylene glycol 0.75% and Ammonium chloride 1% by adding in the drinking water for the first three days followed by 0.75% Ethylene glycol for 18 days. From 8th day till 21st day, standard control received Cystone in the dose of 750 mg/kg. Preventive and curative test groups were treated with hydroalcoholic extract of the test drug in the dose of 132 mg/kg and 264 mg/kg from 1st to 21st day and 8th to 21st day of calculi induction.

RESULTS

Test drug reduced the number of calcium oxalate crystals in the urine; the level of urinary calcium, creatinine, magnesium, phosphorus, sodium and chloride decreased significantly in standard and test groups. The urine volume increased significantly in all the test groups. The level of serum calcium, urea, phosphorus and creatinine were significantly reduced in all the test groups.

CONCLUSIONS

These results indicated that the test drug reduced and prevented the growth of urinary stones. Moreover, the test drug also possessed significant antiurolithiatic activity. However, the protective effect was found more than its curative effect.

Urolithiasis and Its Treatment in Pregnant Women: 10-Year Clinical Experience From a Single Centre

INTRODUCTION

Urolithiasis during pregnancy is an important health concern that can affect maternal and foetal health. If left untreated, it can cause obstetric complications, such as spontaneous abortion and preterm delivery. In this study, we aimed to evaluate urolithiasis and its treatment in pregnant women.

METHODS

We analysed data of 57 patients diagnosed with urolithiasis during pregnancy between January 2010 and December 2020. Patients' age, gestational age, urolithiasis history, physical examination findings, laboratory findings, location and size of the stone and applied treatment methods were examined. The effectiveness and complications of the applied treatment methods were evaluated.

RESULTS

The mean age of 57 patients included in our study was 27 (27.8 ± 5.6) years and their mean gestational age was 20 (20.3 ± 9.2) weeks. The mean stone size was 9 mm (9.09 ± 4.37). The most common symptom at the time of presentation to the hospital was flank pain (93%). Kidney stones were detected in 34 patients and ureteral stones in 23 patients. Although conservative treatment was sufficient in 26 (45.6%) patients, 31 (54.4%) patients required surgical intervention. Major obstetric complications, such as preterm delivery and abortion, did not occur in any of the patients.

CONCLUSION

The diagnosis and treatment of pregnant women with urolithiasis should be managed in a multidisciplinary manner. While determining the treatment options, foetal and maternal health should be considered.

Effect of Phaseolus Vulgaris on Urinary Biochemical Parameters among Patients with Kidney Stones in Saudi Arabia

The study purpose was to investigate the effect of Phaseolus Vulgaris (PV) on urinary biochemical parameters among patients with kidney stones. We conducted a randomized controlled study among 60 patients with kidney stones (size < 10 mm) in the nephrology unit of both government and private hospitals, Al-Ahsa. Urinary volume, calcium, magnesium, potassium, oxalate, uric acid, and power of hydrogen (pH) were assessed before and after the intervention of giving 250 g of PV consumption as an extract thrice weekly (2.2 L to 2.5 L per week) for 6 weeks, which was compared with control. A 't' test was used with the significance at 5%. Mean score of age was 44.5 ± 10.16 in PV group and 43.73 ± 9.79 in control. Four (13.3%) and two (6.7%) had family history of kidney stones. Body mass Index (BMI) mean was 26.44 ± 2.7 and 26.36 ± 2.65 in pre and post-test, respectively, which were significant (p = 0.01017). There were significant changes (p = 0.000) in urine volume from 1962 ± 152.8 to 2005 ± 148.8, calcium 205.4 ± 11.99 to 198.4 ± 12.52, potassium 44.07 ± 3.66 to 52.15 ± 4.37, oxalate 37.12 ± 5.38 to 33.02 ± 5.71, and uric acid 6.88 ± 0.7 to 6.31 ± 0.58. In conclusion, PV is effective management for the patients with kidney stones as it increases the urinary volume and enhances the elimination of small kidney stones.

Do Lifestyle Factors Including Smoking, Alcohol, and Exercise Impact Your Risk of Developing Kidney Stone Disease? Outcomes of a Systematic Review

Introduction: With a rise in the incidence of stone disease, more research is needed to understand the lifestyle factors associated with it. We evaluate available evidence for association of smoking, alcohol, and exercise with kidney stone disease (KSD). Methods: A systematic literature search was conducted in CINAHL, EMBASE, Ovid Medline, Cochrane Library, Scopus, Clinicaltrials.gov, and Google Scholar. Different keywords were "smoking," "cigarette," "alcohol," "spirits," "exercise," "physical activity," "training," "kidney stone," "stone disease," "nephrolithiasis," "urolithiasis," "renal stone," and "urinary stone." The main outcome of interest was the role of smoking, alcohol, and exercise in the development of KSD. Results: A total of 4921 articles were found on searching the databases, of which 14 met the criteria for inclusion in the final review. Studies assessed the following risk factors, physical activity (n = 6), alcohol (n = 6), and smoking (n = 9), and included 17,511 patients. The relationship of physical activity with KSD appears to be equivocal. In addition, only one study demonstrated a decreased risk of nephrolithiasis with alcohol consumption. On the contrary, four studies found a significant association between smoking and renal stone formation. Conclusions: While smoking is one behavioral factor that seems to have some association with KSD, no clear effect of alcohol and physical activity has been demonstrated. To avoid KSD, awareness of the possible detrimental role of smoking should be considered and patients should remain vigilant about the importance of hydration with physical activity. While this represents the most appropriate guidance from the evidence available, at present there remain insufficient data to truly reveal the relationship between these three factors and KSD.

Oxalobacter formigenes reduce the risk of kidney stones in patients exposed to oral antibiotics: a case-control study

This is the first prospective study to investigate the association between kidney stones, bone mineral density, serum testosterone, colon cancer and O. formigenes colonization. 40 kidney stone patients and 85 controls were enrolled. O. formigenes colonization was established. BMD was examined from T- and Z-scores using dual energy absorptiometry. O. formigenes was found in 28 of 40 cases and 80 of 85 controls. BMD was significantly reduced in patients (p < 0.05). The evaluation revealed a significant association between lowered O. formigenes colonization and low testosterone. Urinary calcium and oxalates levels were greater in patient. Serum testosterone and urinary citrate concentrations was reduced in patients with a significant difference. Also an association between O. formigenes and colon cancer was noted. Absence of O. formigenes might stand for a pathogenic factor in calcium oxalate stone, low bone mineral density, low testosterone levels and also colon cancer, when antibiotics are prescribed generously.

Size-Dependent Cytotoxicity of Hydroxyapatite Crystals on Renal Epithelial Cells

Background

Hydroxyapatite (HAP) is a common component of most idiopathic calcium oxalate (CaOx) stones and is often used as a nidus to induce the formation of CaOx kidney stones.

Methods

This work comparatively studies the cytotoxicity of four kinds of HAP crystals with different sizes (40 nm to 2 μm), namely, HAP-40 nm, HAP-70 nm, HAP-1 μm, and HAP-2 μm, on human renal proximal tubular epithelial cells (HK-2).

Results

HAP crystals reduce the viability and membrane integrity of HK-2 cells in a concentration-dependent manner and consequently cause cytoskeleton damage, cell swelling, increased intracellular reactive oxygen species level, decreased mitochondrial membrane potential, increased intracellular calcium concentration, blocked cell cycle and stagnation in G0/G1 phase, and increased cell necrosis rate. HAP toxicity to HK-2 cells increases with a decrease in crystal size.

Conclusion

Cell damage caused by HAP crystals increases the risk of kidney stone formation.

Vitamin D receptor gene polymorphisms and susceptibility to urolithiasis: a meta-regression and meta-analysis

BACKGROUND

The currently available data with respect to the association between vitamin D receptor (VDR) gene polymorphism and risk to urolithiasis are inconclusive and inconsistent. Hence, an exhaustive meta-analysis can solve the discrepancies and provide a hint for upcoming investigations. Herein, a meta-analysis was carried out to attain a conclusive estimate of the association between VDR gene single nucleotide polymorphisms (SNPs) and urolithiasis risk.

METHODS

The major databases, including ISI Web of science, Scopus, and PubMed/MEDLINE were searched systematically from until June 2020 to retrieve all relevant studies. Association between VDR gene polymorphisms, including FokI (rs2228570), TaqI (rs731236), BsmI (rs1544410), and ApaI (rs7975232), and urolithiasis risk was evaluated using pooled odds ratio (OR) and their corresponding 95% confidence interval (CI). Additionally, to seek for the potential source of heterogeneity, meta-regression analyses were exerted.

RESULTS

Literature search led to finally finding of 33 studies evaluating the VDR gene SNPs and urolithiasis risk. It was observed that none of the four SNPs were significantly associated with urolithiasis predisposition. However, subgroup analysis confirmed higher risk of urolithiasis in East-Asian and Caucasian population with ApaI and TaqI gene polymorphism. The analyses of sensitivity acknowledged the results stability.

CONCLUSION

Although this meta-analysis did not support the association of FokI, TaqI, BsmI, and ApaI in the overall polled analysis, it suggests that ApaI and TaqI SNPs is associated with increased risk of urolithiasis in East-Asian and Caucasians populations.

Phytochemical and Pharmacological Study on the Leaves of Bauhinia Purpurea L. for Antilithiatic Activity

The main purpose of this study was to investigate the impact of ethanolic concentrate of Bauhinia purpurea L. leaves on lithiatic action in rat. Twenty four rats were divided into 6 groups comprising four animals per groups. The blood was collected from the retro-orbital sinus; serum was separated by centrifugation and analyzed for creatinine and uric acid. Both kidneys from each animal were removed and sectioned for histopathological examination. The results were expressed as mean ± standard error mean (SEM) and the statistical significance was assessed using one-way analysis of variance (ANOVA) followed by Dunnett’s comparison test and p<0.05 was considered significant. In the present in-vivo study, renal stone inciting treatment to rodents came about in hyper-oxaluria. Ethanolic concentrate of B. purpurea L. was exposed to antilithiatic action in rodents where ethylene glycol 0.75% (v/v) utilized as the causing lithiasis specialist. Ethanolic concentrate of B. purpurea (at 100 and 200 mg/kg) showed a portion subordinate noteworthy enemy of lithiatic action on treatment. The concentrate portion of 100 mg/kg likewise caused decrease of Ca, oxalates, P and creatinine in blood serum level the outcomes were found factually noteworthy. The impact of ethanol concentrate of this movement was discovered critical than the reference standard. By and large investigation uncovers that the ethanolic concentrate of B. purpurea L. demonstrates the mellow to direct antilithiatic movement with correlation with cystone.

Does chronic hyperglycaemia increase the risk of kidney stone disease? results from a systematic review and meta-analysis

DESIGN

Systematic review and meta-analysis of observational studies was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for studies reporting on diabetes mellitus (DM) or metabolic syndrome (MetS) and kidney stone disease (KSD).

OBJECTIVE

To examine the association between chronic hyperglycaemia, in the form of DM and impaired glucose tolerance (IGT) in the context of MetS and KSD.

SETTING

Population-based observational studies. Databases searched: Ovid MEDLINE without revisions (1996 to June 2018), Cochrane Library (2018), CINAHL (1990 to June 2018), ClinicalTrials.gov, Google Scholar and individual journals including the Journal of Urology, European Urology and Kidney International.

PARTICIPANTS

Patients with and without chronic hyperglycaemic states (DM and MetS).

MAIN OUTCOME MEASURES

English language articles from January 2001 to June 2018 reporting on observational studies.

EXCLUSIONS

No comparator group or fewer than 100 patients. Unadjusted values were used for meta-analysis, with further meta-regression presented as adjusted values. Bias was assessed using Newcastle-Ottawa scale.

RESULTS

2340 articles were screened with 13 studies included for meta-analysis, 7 DM (three cohort) and 6 MetS. Five of the MetS studies provided data on IGT alone. These included: DM, n=28 329; MetS, n=31 767; IGT, n=12 770.

CONTROLS

DM, n=5 89 791; MetS, n=1 78 050; IGT, n=2 93 852 patients. Adjusted risk for DM cohort studies, RR=1.23 (0.94 to 1.51) (p<0.001). Adjusted ORs for: DM cross-sectional/case-control studies, OR=1.32 (1.21 to 1.43) (p<0.001); IGT, OR=1.26 (0.92 to 1.58) (p<0.0001) and MetS, OR=1.35 (1.16 to 1.54) (p<0.0001). There was no significant difference between IGT and DM (cross-sectional/case-control), nor IGT and MetS. There was a moderate risk of publication bias. Statistical heterogeneity remained significant in adjusted DM cohort values and adjusted IGT (cross-sectional/case-control), but non-signficant for adjusted DM (cross-sectional/case-control).

CONCLUSION

Chronic hyperglycaemia increases the risk of developing kidney stone disease. In the context of the diabetes pandemic, this will increase the burden of stone related morbidity and mortality.

PROSPERO REGISTRATION NUMBER

CRD42018093382.

Influence of various uropathogens on crystallization of urine mineral components caused by Proteus mirabilis

Infectious urolithiasis is a consequence of long-standing urinary tract infections with urease-positive bacteria, especially Proteus spp. However, because of the often mixed nature of urinary tract infections, in the case of urinary stones formation, several species of bacteria may be involved in the process. The purpose of the study was to determine the impact of the bacterial species: Escherichia coli, Klebsiella pneumoniae, Providencia stuartii, Pseudomonas aeruginosa and Staphylococcus aureus on the crystallization caused by Proteus mirabilis. The studies were conducted in synthetic urine with the addition of P. mirabilis and a representative of another species. During the experiments the viability of bacteria, pH, presence and morphology of crystals, and the intensity of crystallization were assessed. Crystallization of calcium and magnesium phosphates occurred in all investigated configurations. However, there were differences observed in the course and intensity of crystallization between the mixed culture and the P. mirabilis culture. Although most intense crystallization took place in the pure culture of P. mirabilis it was also demonstrated that the presence of other uropathogens increased the survival of P. mirabilis. This synergistic effect could be responsible for the persistence and recurrence of urolithiasis in the urinary tract.

Epidemiology of urolithiasis consultations in the Paraíba Valley

OBJECTIVE

to know the epidemiological profile of patients with urolithiasis in the Paraíba Valley region, identifying its prevalence and spatial distribution.

METHOD

we conducted a cross-sectional study, by residence location in the Paraíba Valley, on morbidity data due to urolithiasis obtained from the DATASUS, covering the period between 2010 and 2012. We aimed at identifying the general, male and female prevalence of urolithiasis, the distribution by age, type of visit, year season and spatial distribution.

RESULTS

there were 1,901 visits for urolithiasis in the 35 municipalities of the Paraíba Valley in the three years studied, 52.3% of them of female patients. Of the total, 70.1% of the visits were emergency ones. The feminine visits (67.2%) were mostly also urgent (p <0.01). The overall prevalence for urolithiasis was 31.7/100,000. Male prevalence was 30.7/100,000, and the female, 32.7/100,000 (p>0.05). The prevalence ratio was 0.9 men for every woman. The age group with the highest prevalence was between 30 and 39 years, with 23.1%. Warm seasons concentrated 51.6% of cases, while 48.8% occurred in the cold ones (p>0.05) .

CONCLUSION

women are more affected by urolithiasis than the male in the Paraíba Valley region, an unprecedented in the literature. There was no relationship between the year season and the disease. We identified municipalities where preventive actions of urinary lithogenesis are required.

Kidney Stone Disease: An Update on Current Concepts

Kidney stone disease is a crystal concretion formed usually within the kidneys. It is an increasing urological disorder of human health, affecting about 12% of the world population. It has been associated with an increased risk of end-stage renal failure. The etiology of kidney stone is multifactorial. The most common type of kidney stone is calcium oxalate formed at Randall's plaque on the renal papillary surfaces. The mechanism of stone formation is a complex process which results from several physicochemical events including supersaturation, nucleation, growth, aggregation, and retention of urinary stone constituents within tubular cells. These steps are modulated by an imbalance between factors that promote or inhibit urinary crystallization. It is also noted that cellular injury promotes retention of particles on renal papillary surfaces. The exposure of renal epithelial cells to oxalate causes a signaling cascade which leads to apoptosis by p38 mitogen-activated protein kinase pathways. Currently, there is no satisfactory drug to cure and/or prevent kidney stone recurrences. Thus, further understanding of the pathophysiology of kidney stone formation is a research area to manage urolithiasis using new drugs. Therefore, this review has intended to provide a compiled up-to-date information on kidney stone etiology, pathogenesis, and prevention approaches.

Stress-stones-stress-recurrent stones: a self-propagating cycle? Difficulties in solving this dichotomy

Numerous studies have reported an association between stress and urolithiasis. Although urinary risk factors have been measured in several of these, compelling evidence of a causal relationship has not been established. A shortcoming is that alterations in single urinary parameters rather than ratios and quotients, which provide a more synergistic risk evaluation, have been measured. Recently, we speculated about a possible association between chronic stress and stone recurrence. This presents an intriguing dichotomy of whether stress causes stones or vice versa, or whether they are linked in a self-propagating stress-stones-stress-recurrence cycle. We investigated the latter hypothesis in a retrospective case-control designed study in which we calculated urinary ratios and quotients which are regarded as diagnostic indicators of stone risk. These included Ca/Cr, Ox/Cr, Mg/Cr, Cit/Cr, urate/Cr and citrate-magnesium-calcium ratios, activity product quotient for calcium oxalate (CaOx) and relative supersaturation of CaOx, brushite and uric acid. Overnight urinary data from 128 participants comprising 31 first time (FS), 33 recurrent (RS) CaOx stone formers and 64 controls were used. All subjects had been previously assessed for chronic stress dimensions, as well as for stress caused by their stone episodes per se. Conditional and unconditional logistic regression (with a Bonferroni correction for multiple tests) and simple linear regression were used to analyse various components of the data. Although RS had more stressful life events, with greater intensity of perception than FS, there were no significant differences between the groups regarding any of the urinary risk factors. No significant association between stressful life events and any of the urinary ratios or quotients was observed. A direct causal link between stress and stone recurrence was not indicated. We believe that future studies should shift their focus from traditional urinary risk factors to other stone-forming mechanisms. However, we recognize that there is an inherent problem in attempting to solve the stress-stones dichotomy as it would be impossible to disentangle alterations in risk factors which arise from lifestyle stress and those arising from stone episodes themselves.

Urolithiasis in pregnancy

Urolithiasis in pregnancy is a major health concern and can potentially affect the well-being of both mother and foetus. Management of this condition often entails simultaneous multidisciplinary involvement of obstetrician, radiologist and urologist. Additionally, adverse effects with usage of anaesthesia, radiation, medications and surgery on mother and foetus, limit utilisation of the full armamentarium of diagnostic and therapeutic modalities that are commonly used in non-pregnant women. This review was conducted using an electronic literature search of peer reviewed journal articles. Clinical studies were identified in the bibliographic database- PubMed (Medline), Ovid and eMedicine(WebMD) using the keywords: hydronephrosis, urolithiasis, kidney stone, urinary tract infection, pregnancy and ultrasound, incidence and epidemiology of renal stones.

Comparative risk of chronic kidney diseases in patients with urolithiasis and urological interventions: a longitudinal population-based study

Large cohort studies on whether any association existed between urological interventions for urolithiasis and the development of CKD are lacking. From claims data of the National Health Insurance (NHI) program of Taiwan, we identified 54,433 patients newly diagnosed with urolithiasis during 1998-2010. For each case, four individuals without urolithiasis were randomly selected and frequency matched by age, sex, and diagnosis year. Both groups were followed up until the end of 2010. Incident CKD events were identified by the International Classification of Diseases, Ninth Revision (ICD-9) code in the NHI registration database. The overall incidence of periodontal diseases was 1.85-fold greater in the urolithiasis group than in the comparison group (33.9 vs 18.3 per 10,000 person-years; 95 % confidence interval [CI] 1.81-1.90). Compared with the adjusted hazard ratios (aHRs) of nonurolithiasis patients, those of patients with urolithiasis increased with the number of medical visits (from 0.91 [95 % CI 0.83-1.00] to 10.6 [95 % CI 9.48-11.8]) and urological interventions (from 1.22 [95 % CI 1.10-1.35] to 86.4 [95 % CI 67.6-110.6]). The aHR was similar in different urological intervention methods, extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrostolithotomy, and open stone surgery. The urological intervention for urolithiasis is associated with an increased risk of CKD. We should be aware of the risk for CKD, especially in patients who have received multiple urological interventions and those elderly.

Evaluating the Patient with Left Lower Quadrant Abdominal Pain

Left lower quadrant pain is a frequent indication for imaging in the emergency department. Most causes of pain originate from the colon, including diverticulitis, colitis, fecal impaction, and epiploic appendagitis. Left-sided urolithiasis and spontaneous hemorrhage in the retroperitoneum or rectus sheath are additional causes of pain. Computed tomography is the preferred imaging modality in the emergent setting for all of these pathologic conditions. Gynecologic, testicular, and neoplastic pathology may also cause left lower quadrant pain but are not discussed in this article.

Modeling the distribution of urolithiasis prevalence under projected climate change in Iran

Although studies support a positive correlation between temperature and stone risk, the precise relationship between these factors has not been elucidated. We modeled the current distribution of urolithiasis prevalence in Iran using 26 bioclimatic, climatic and topographic variables based on two multivariate linear regression models in geographical information system. The impact of climate change on the stone prevalence was predicted under the projections of GFDL-ESM2G, CCSM4 and HadGEM2-ES climate models by mid-century (2050). Extraterrestrial radiation and isothermality in the first regression model and annual mean temperature, precipitation seasonality and isothermality in the second model were the significant (P<0.01) predictors of urolithiasis prevalence. Both regression models provided good estimates of the stone prevalence (R2>0.9) and determined a mean urolithiasis prevalence of 6% (range of 1.5-10.8%) in Iran. The climate change under the projections of GFDL-ESM2G, CCSM4 and HadGEM2-ES models can, respectively, lead to an average increase of 5.7, 4.3 and 9% in the urolithiasis prevalence based on the second regression model by 2050. The highest increase of the prevalence will occur in the west, northwest and southwest provinces of the country. Predicting the impact of climate change on climate-related diseases can be useful for effective preventive measures.

Induced urinary crystal formation as an analytical strategy for the prediction and monitoring of urolithiasis and other metabolism-related disorders

Crystal formation reflects the entire composition of the surrounding solution. In case of urolithiasis, induced crystal formation in native urine has led to the development of the Bonn-Risk-Index (BRI), a valuable tool to quantify an individual's risk of calcium oxalate urolithiasis. If the progression of a disease is associated with characteristic changes in the activities of urinary components, this leads to an altered urinary crystallisation capacity. Therefore, the results of induced urinary crystal formation can be used to detect and monitor any disease linked to the altered urinary composition. Since crystal formation inherently takes into account the entire urinary composition, the influence of the disease on individual urinary parameters does not have to be known in order to monitor the consequent pathologic alterations. In this paper, we review the background of urinary crystal formation analysis and describe its established application in urolithiasis monitoring as well as potential further fields of clinical application.

Effect of renal insufficiency on stone recurrence in patients with urolithiasis

The study was designed to assess the relationship between glomerular filtration rate (GFR) and urinary stone-forming constituents, and to assess the effect of renal insufficiency on stone recurrence risk in first stone formers (SF). Baseline serum creatinine levels were obtained, and renal insufficiency was defined as creatinine clearance ≤60 mL/min (Cockroft-Gault). This retrospective case-control study consists of 342 first SF; 171 SF with normal renal function were selected with 1:1 propensity scores matched to 171 SF with renal insufficiency. Urinary metabolic evaluation was compared to renal function. GFR was positively correlated with urinary calcium, uric acid, and citrate excretion. Subjects with renal insufficiency had significantly lower urinary calcium, uric acid, and citrate excretion than those with normal renal function, but not urine volume. With regard to urinary metabolic abnormalities, similar results were obtained. SF with renal insufficiency had lower calcium oxalate supersaturation indexes and stone recurrence rates than SF with normal renal function. Kaplan-Meier curves showed similar results. In conclusion, GFR correlates positively with urinary excretion of stone-forming constituents in SF. This finding implies that renal insufficiency is not a risk factor for stone recurrence.