Urolithiasis and the risk of ESRD

PPARγ agonist alleviates calcium oxalate nephrolithiasis by regulating mitochondrial dynamics in renal tubular epithelial cell

BACKGROUND

Kidney stone formation is a common disease that causes a significant threat to human health. The crystallization mechanism of calcium oxalate, the most common type of kidney stone, has been extensively researched, yet the damaging effects and mechanisms of calcium oxalate crystals on renal tubular epithelial cells remain incompletely elucidated. Regulated mitochondrial dynamics is essential for eukaryotic cells, but its role in the occurrence and progression of calcium oxalate (CaOx) nephrolithiasis is not yet understood.

METHODS

An animal model of calcium oxalate-related nephrolithiasis was established in adult male Sprague‒Dawley (SD) rats by continuously administering drinking water containing 1% ethylene glycol for 28 days. The impact of calcium oxalate crystals on mitochondrial dynamics and apoptosis in renal tubular epithelial cells was investigated using HK2 cells in vitro. Blood samples and bilateral kidney tissues were collected for histopathological evaluation and processed for tissue injury, inflammation, fibrosis, oxidative stress detection, and mitochondrial dynamics parameter analysis.

RESULTS

Calcium oxalate crystals caused higher levels of mitochondrial fission and apoptosis in renal tubular epithelial cells both in vivo and in vitro. Administration of a PPARγ agonist significantly alleviated mitochondrial fission and apoptosis in renal tubular epithelial cells, and improved renal function, accompanied by reduced levels of oxidative stress, increased antioxidant enzyme expression, alleviation of inflammation, and reduced fibrosis in vivo.

CONCLUSION

Our results indicated that increased mitochondrial fission in renal tubular epithelial cells is a critical component of kidney injury caused by calcium oxalate stones, leading to the accumulation of reactive oxygen species within the tissue and the subsequent initiation of apoptosis. Regulating mitochondrial dynamics represents a promising approach for calcium oxalate nephrolithiasis.

Vascular calcification in kidney stone formers: the impact of age and stone composition

An increased prevalence of vascular calcification (VC) has been reported in kidney stone formers (KSFs), along with an elevated cardiovascular risk. The aim of the current study is to assess whether VC in these patients develops at a younger age and is influenced by stone composition. This single-center, matched case-control study included KSFs with uric acid or calcium oxalate stones (diagnosed based on stone analysis) and age- and sex-matched controls without a history of nephrolithiasis. The prevalence and severity of abdominal aortic calcification (AAC) and bone mineral density (BMD) were compared between KSFs and non-KSFs. In total, 335 patients were investigated: 134 with calcium oxalate stones, 67 with uric acid stones, and 134 controls. Overall, the prevalence of AAC was significantly higher among calcium stone formers than among the controls (67.9% vs. 47%, p = 0.002). In patients under 60 years of age, those with calcium oxalate stones exhibited both a significantly elevated AAC prevalence (61.9% vs. 31.3%, p = 0.016) and severity (94.8 ± 15.4 vs. 30.3 ± 15.95, p = 0.001) compared to the controls. Within the age group of 40-49, osteoporosis was identified only in the KSFs. Multivariate analysis identified age, smoking, and the presence of calcium stones as independent predictors of AAC. This study highlights that VC and osteoporosis occur in KSFs at a younger age than in non-stone-formers, suggesting potential premature VC. Its pathogenesis is intriguing and needs to be elucidated. Early evaluation and intervention may be crucial for mitigating the cardiovascular risk in this population.

Safety and efficacy of enhanced recovery after surgery among patients undergoing percutaneous nephrolithotomy: a systematic review and meta-analysis

BACKGROUND

The enhanced recovery after surgery (ERAS) method has been widely used in surgery and anesthesia worldwide and has been applied to a wide range of surgical specialties, including colorectal surgery, gynecology, liver surgery, breast surgery, urology, and spinal surgery. An increasing number of studies have demonstrated its safety and efficacy in various fields. The safety and effectiveness of ERAS for percutaneous nephrolithotomy (PCNL) remain controversial. This study aimed to review the safety and effectiveness of ERAS for PCNL.

METHODS

The Chinese National Knowledge Infrastructure (CNKI), Wan Fang, Chinese Biomedical Literature Service System (SinoMed), Chinese Science and Technology Journal Full Text Database (VIP), Cochrane Library, PubMed, Web of Science, and Embase databases were searched for eligible studies published until 19 September 2022. Outcome measures included postoperative hospital stay, total hospital stay, incidence of postoperative complications, stone-free rate (SFR), operative time, postoperative indwelling nephrostomy tube time, catheter encumbrance time, and nursing satisfaction. All analyses were performed using random-effects or fixed-effects models. Clinical heterogeneity was treated with subgroup, sensitivity, or descriptive analyses only when clinical heterogeneity was not excluded. Publication bias was assessed using funnel plots. Twenty-five studies (1545 observational patients and 1562 controls) were included.

RESULTS

The ERAS group had a shorter postoperative hospital stay [WMD=-2.59, 95% CI=(-3.04, -2.14), P <0.001], total hospital stay [WMD=-2.59, 95% CI=(-3.04, -2.14), P <0.001], and lower complication rate [RR=0.36, 95% CI=(0.29-0.43), P <0.001] than the control group. The ERAS group had a shorter surgery time [WMD=-3.57, 95% CI=(-5.88, -1.26), P =0.003], postoperative indwelling nephrostomy tube time [WMD=-1.94, 95% CI=(-2.69, -1.19), P <0.001], catheter encumbrance time [WMD=-2.65, 95% CI=(-4.83, -0.46), P =0.02], and higher satisfaction [RR=1.15, 95% CI=(1.05-1.25), P =0.001] than the control group. The difference in the stone-free rate between the two groups was not statistically significant [RR=1.03, 95% CI=(0.97-1.09), P =0.38], but the stone-free rate of the observation group (ERAS group) in each study was higher than that of the control group.

CONCLUSION

ERAS not only ensures the safety of PCNL but also promotes postoperative rehabilitation of patients (shorter surgery time, postoperative indwelling nephrostomy tube time, postoperative hospital time, and lower complication rate). At the same time, differences in the stone-free rate were not statistically significant, but the stone-free rate of ERAS in each study was higher than that of the usual care for PCNL patients.

Risk of incident chronic kidney disease among patients with urolithiasis: a nationwide longitudinal cohort study

Background

Urolithiasis has been infrequently implicated to have a causal association with chronic kidney disease (CKD). Recently, several studies have demonstrated the relationship between urolithiasis and CKD. However, the generalizability of their results is limited. This study aimed to investigate the association between urolithiasis and the risk of incident CKD.

Methods

This longitudinal cohort study used the National Health Insurance Service data, including 219 570 Korean adults with incident urolithiasis requiring procedural interventions and without prior kidney disease and 219 570 age- and sex-matched controls without urolithiasis between 1 January 2002 and 31 December 2020. Primary outcome was the development of CKD, defined by an estimated glomerular filtration rate <60 ml/min/1.73 m2 for at least two consecutive measurements at least 90 days apart. The risk for incident CKD was further examined using the outcome defined by newly occurring diagnostic codes indicating CKD.

Results

Over a mean follow-up of 6 years, 12 338 (2.8%) primary outcome events of CKD were observed (incidence rate 4.6/1000 person-years). Per multivariable Cox analysis, urolithiasis was associated with a higher risk of incident CKD [adjusted hazard ratio 1.41 (95% confidence interval 1.36-1.46)]. This association remained consistent across all clinically relevant subgroups and when the CKD outcome was defined based on the diagnostic codes in the sensitivity analysis.

Conclusions

In this large national cohort study, patients with urolithiasis were associated with a higher risk of incident CKD than those without urolithiasis. Further studies are warranted to establish the benefits of preventing urolithiasis in reducing CKD development.

Safety and efficacy of a polyherbal formulation from traditional Persian medicine in patients with calcium kidney stones: A randomized, double-blinded clinical trial

Background

10%-15% of the world's population suffers from kidney stones. Nearly 50% increase was observed in diagnosing and treating nephrolithiasis in the last decades. Effective medical treatment for the disease is not yet well established. Moreover, there is an increasing global demand to manage diseases using complementary and alternative medicine. This study aimed to formulate and assess the safety and efficacy of a multi-ingredient formulation from traditional Persian medicine (TPM) known as Mofatet powder in patients suffering from calcium kidney stones.

Materials and Methods

The aqueous extract of Mofatet powder was prepared, freeze-dried, and formulated as capsules. 26 patients in the drug group and 25 patients in the placebo group used 500 mg capsules of the drug/placebo twice daily for 5 weeks. Ultrasonography/kidney, ureter and bladder imaging, urine analysis, and biochemical parameters were evaluated before and after the intervention.

Results

The imaging results showed a 60.73% decrease (P < 0.001) in stone size in the drug group. Moreover, the urinary calcium decreased (P = 0.02) and the urinary magnesium increased (P < 0.001) in the drug group. No remarkable changes were observed in the placebo group in these parameters. No significant effect was observed in aspartate transaminase, alanine transaminase, serum creatinine, and blood urea nitrogen levels in none of the groups.

Conclusion

This study suggests that Mofatet powder was effective in reducing calcium kidney stones size with no potential nephro/hepatotoxicity. After confirming these results in larger clinical trials with longer duration, this formulation can be considered a treatment for nephrolithiasis.

Rac1 promotes kidney collecting duct repair by mechanically coupling cell morphology to mitotic entry

Prolonged obstruction of the ureter, which leads to injury of the kidney collecting ducts, results in permanent structural damage, while early reversal allows for repair. Cell structure is defined by the actin cytoskeleton, which is dynamically organized by small Rho guanosine triphosphatases (GTPases). In this study, we identified the Rho GTPase, Rac1, as a driver of postobstructive kidney collecting duct repair. After the relief of ureteric obstruction, Rac1 promoted actin cytoskeletal reconstitution, which was required to maintain normal mitotic morphology allowing for successful cell division. Mechanistically, Rac1 restricted excessive actomyosin activity that stabilized the negative mitotic entry kinase Wee1. This mechanism ensured mechanical G2-M checkpoint stability and prevented premature mitotic entry. The repair defects following injury could be rescued by direct myosin inhibition. Thus, Rac1-dependent control of the actin cytoskeleton integrates with the cell cycle to mediate kidney tubular repair by preventing dysmorphic cells from entering cell division.

Management of de novo nephrolithiasis after kidney transplantation: a comprehensive review from the European Renal Association CKD-MBD working group

The lifetime incidence of kidney stones is 6%-12% in the general population. Nephrolithiasis is a known cause of acute and chronic kidney injury, mediated via obstructive uropathy or crystal-induced nephropathy, and several modifiable and non-modifiable genetic and lifestyle causes have been described. Evidence for epidemiology and management of nephrolithiasis after kidney transplantation is limited by a low number of publications, small study sizes and short observational periods. Denervation of the kidney and ureter graft greatly reduces symptomatology of kidney stones in transplant recipients, which may contribute to a considerable underdiagnosis. Thus, reported prevalence rates of 1%-2% after kidney transplantation and the lack of adverse effects on allograft function and survival should be interpreted with caution. In this narrative review we summarize current state-of-the-art knowledge regarding epidemiology, clinical presentation, diagnosis, prevention and therapy of nephrolithiasis after kidney transplantation, including management of asymptomatic stone disease in kidney donors. Our aim is to strengthen clinical nephrologists who treat kidney transplant recipients in informed decision-making regarding management of kidney stones. Available evidence, supporting both surgical and medical treatment and prevention of kidney stones, is presented and critically discussed. The specific anatomy of the transplanted kidney and urinary tract requires deviation from established interventional approaches for nephrolithiasis in native kidneys. Also, pharmacological and lifestyle changes may need adaptation to the specific situation of kidney transplant recipients. Finally, we point out current knowledge gaps and the need for additional evidence from future studies.

Comparison of STONE Score, Guy's Stone Score, CROES Nomogram, and Seoul National University Renal Stone Complexity Score in Prognosticating Outcomes of Multiple-Tract Mini-Percutaneous Nephrolithotomy: A Retrospective Study

Objective  The objective of this study was to compare the STONE score (Size of the stone, Topography or location, degree of Obstruction of the urinary system, Number of stones, and Evaluation of Hounsfield units), Guy's stone score (GSS), Clinical Research Office of the Endourological Society (CROES) nomogram, and Seoul National University Renal Stone Complexity Score (RSCS) in prognosticating multiple tract mini-percutaneous nephrolithotomy (mPCNL) outcome. Methodology This descriptive retrospective analysis was carried out at the Urology Department, Lady Reading Hospital, Peshawar, Pakistan. Male and female patients in the age range of 18-70 years who underwent multiple tract mPCNL for renal stones from July 1, 2021, to June 30, 2023, were included in the analysis. Results  A total of 110 patients were registered. Stone-free status (SFS) was achieved in 78.2% (n=86), and complications were observed in 13.6% (n=15) patients. The odds ratio for STONE score, GSS, CROES scoring system, and RSCS for predicting the SFS was 7.093 (95%CI 2.40-20.89), 9.333 (95%CI 2.92-29.81), 11.70 (95%CI 2.56-53.38) and 3.450 (95%CI 1.25-9.53), respectively. Conclusion  Multiple tract mPCNL is a safe and effective technique for the management of renal stones, producing a high stone-free rate. This study demonstrated adequate efficacy and dependability of the four scoring systems in predicting SFS.

The experience of a tertiary referral center with laparoscopic pyelolithotomy for large renal stones during 18 years

This study aimed to evaluate the outcomes of laparoscopic pyelolithotomy, including its efficacy and feasibility in treatment of large renal stones. All patients who underwent laparoscopic pyelolithotomy operations in a referral center were enrolled from 2003 to 2020. The final analysis included 436 patients. The total stone free rate was 88.3% and the stone-free rate for staghorn/multiple stones versus other types of stones was 81% vs. 91% (P = 0.002). Likewise, the total operation duration was 158 ± 50 and the operation duration for staghorn/multiple stones versus other types of stones was 171 ± 51 min vs. 153 ± 49 min (P < 0.001). The operation duration (169 ± 51 vs. 155 ± 58 vs. 155 ± 42 min) and hospitalization (4.5 ± 2.3 vs. 4.0 ± 2.2 vs. 3.6 ± 1.8) decreased with increasing the surgeons' experience over time. The outcomes of laparoscopic pyelolithotomy for children versus adults versus geriatric patients and in patients with normal versus abnormal kidney anatomy did not reveal statistically significant differences. Laparoscopic pyelolithotomy could be employed as an alternative surgical approach for patients with large kidney stones of any age or with kidney abnormalities provided that appropriate expertise is available to carry out the procedure.

Hydration for Adult Patients with Nephrolithiasis: Specificities and Current Recommendations

Nephrolithiasis affects around 10% of the population and is frequently associated with impaired dietary factors. The first one is insufficient fluid intake inducing reduced urine volume, urine supersaturation, and subsequently urinary lithiasis. Kidneys regulate 24 h urine volume, which, under physiological conditions, approximately reflects daily fluid intake. The aim of this study is to synthesize and highlight the role of hydration in the treatment of nephrolithiasis. Increasing fluid intake has a preventive effect on the risk of developing a first kidney stone (primary prevention) and also decreases the risk of stone recurrence (secondary prevention). Current guidelines recommend increasing fluid intake to at least at 2.5 L/day to prevent stone formation, and even to 3.5-4 L in some severe forms of nephrolithiasis (primary or enteric hyperoxaluria or cystinuria). Fluid intake must also be balanced between day and night, to avoid urinary supersaturation during the night. Patients should be informed and supported in this difficult process of increasing urine dilution, with practical ways and daily routines to increase their fluid intake. The liquid of choice is water, which should be chosen depending on its composition (such as calcium, bicarbonate, or magnesium content). Finally, some additional advice has to be given to avoid certain beverages such as those containing fructose or phosphoric acid, which are susceptible to increase the risk of nephrolithiasis.

Safety and efficacy of enhanced recovery after surgery among patients undergoing percutaneous nephrolithotomy: protocol for a systematic review and meta-analysis

INTRODUCTION

Enhanced recovery after surgery is widely used in the perioperative period in the field of urology; however, it lacks comprehensive and systematic evidence supporting its efficacy and safety after percutaneous nephrolithotomy. This meta-analysis aimed to assess the safety and efficacy of enhanced recovery after percutaneous nephrolithotomy.

METHODS AND ANALYSIS

Relevant databases, including PubMed, Web of Science, Embase, The Cochrane Library, China Knowledge Resource Integrated Database, Wanfang Database, Chinese Biomedical Document Service System, and Chinese Science and Technology Journal Database, will be searched from their inception to 19 September 2022. Two researchers will independently screen the literature, extract data and evaluate the included studies. The Grading of Recommendations, Assessment, Development, and Evaluation will be used to assess the degree of certainty of the evidence. Based on the Cochrane Handbook V.5.1.0, the risk of bias assessment of the included randomised controlled trials will be assessed. Based on their randomisation method, allocation generation, concealment, blinding and follow-up, we will assess randomised controlled trials. Random-effects and fixed-effects models and subgroup analyses will be used for meta-analysis. RevMan V.5.4.1 will be used for data collection and meta-analysis.

ETHICS AND DISSEMINATION

Due to the nature of this systematic review, ethics approval is not required for this study. We will publish the results of this review in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42023411520.

Lifestyle factors, serum parameters, metabolic comorbidities, and the risk of kidney stones: a Mendelian randomization study

Background and objective

The early identification of modifiable risk factors is important for preventing kidney stones but determining causal associations can be difficult with epidemiological data. We aimed to genetically assess the causality between modifiable factors (lifestyle factors, serum parameters, and metabolic comorbidities) and the risk of kidney stones. Additionally, we aimed to explore the causal impact of education on kidney stones and its potential mediating pathways.

Methods

We conducted a two-sample Mendelian randomization (MR) study to explore the causal association between 44 modifiable risk factors and kidney stones. The FinnGen dataset initially explored the causal relationship of risk factors with kidney stones and the UK Biobank dataset was used as the validation set. Then, a meta-analysis was conducted by combining discovery and validation datasets. We used two-step MR to assess potential mediators and their mediation proportions between education and kidney stones.

Results

The combined results indicated that previous exposures may increase the risk of kidney stones, including sedentary behavior, urinary sodium, the urinary sodium/potassium ratio, the urinary sodium/creatinine ratio, serum calcium, 25-hydroxyvitamin D (25OHD), the estimated creatinine-based glomerular filtration rate (eGFRcrea), GFR estimated by serum cystatin C (eGFRcys), body mass index (BMI), waist circumference, type 2 diabetes mellitus (T2DM), fasting insulin, glycated hemoglobin, and hypertension. Coffee intake, plasma caffeine levels, educational attainment, and the urinary potassium/creatinine ratio may decrease the risk of kidney stones. Ranked by mediation proportion, the effect of education on the risk of kidney stones was mediated by five modifiable risk factors, including sedentary behavior (mediation proportion, 25.7%), smoking initiation (10.2%), BMI (8.2%), T2DM (5.8%), and waist circumference (3.2%).

Conclusion

This study provides MR evidence supporting causal associations of many modifiable risk factors with kidney stones. Sedentary lifestyles, obesity, smoking, and T2DM are mediating factors in the causal relationship between educational attainment and kidney stones. Our results suggest more attention should be paid to these modifiable factors to prevent kidney stones.

SPP1 and UMOD gene variants are synergistically associated with risk of renal stone disease

OBJECTIVE

Calcium and oxalate are the most abundant metabolites present in the stone matrix. The SPP1 and UMOD gene has specific expression in kidneys and are involved in various stages of stone formation. Therefore, genetic variants in the SPP1 and UMOD genes may enhance the development of renal stone disease. This study has been designed to understand the association of genetic variants of SPP1 and UMOD genes with renal stone disease.

MATERIALS AND METHOD

A prospective study has been carried out, including 150 renal stone disease patients and 150 healthy individuals. Biochemical parameters were performed, including serum calcium levels, creatinine, parathyroid hormone, and 24-Hour urine metabolites. The genotyping of SPP1 (rs1126616) and UMOD (rs4293393) gene variants were performed using a customized TaqMan probe. T-test was used for continuous biochemical data analysis. The Chi-square test has been applied to assess the risk of a particular genotype associated with renal stone disease. In addition, correlation analysis for biochemical parameters and genetic variants with the renal stone disease has been performed using Shapley additive explanations (SHAP) values calculated with the help of the pycaret library.

RESULT

Renal stone patients had significantly higher levels of parathyroid hormone (93.37 ± 52.78 pg/ml vs 64.67 ± 31.50 pg/ml, P=<0.0001), serum creatinine (0.94 ± 0.38 mg/dl vs 0.77 ± 0.17 mg/dl, P=<0.0001) and 24hr urine metabolites in comparison to the healthy controls. Heterozygous (CT) variant of SPP1 and homozygous (GG) variant of UMOD genes were significantly associated with an increased risk of developing the renal stone disease (p = 0.0100, OR = 2.06, 95 %CI = 1.13-3.75; p=<0.0001, OR = 5.773, 95 % CI = 2.03-16.38, respectively). Individuals with hyperparathyroidism and CC (SPP1) and GG (UMOD) genotypes have a high risk (P = 0.0055, OR = 2.75, 95 %CI = 1.35-5.67; P = 0.0129, OR = 10.03, 95 %CI = 1.60-110.40, respectively) of developing a renal stone. In addition, individuals with hypercalciuria and TT genotype of SPP1 (P = 0.0112, OR = 2.92, 95 % CI = 1.33-6.35), AG genotype of UMOD (P=<0.0001, OR = 5.45, 95 %CI = 2.24-13.96) and GG genotype of UMOD (P=<0.0001, OR = 10.02, 95 %CI = 3.53-24.63) have high risk of developing renal stones. Moreover, Individuals with hyperoxaluria and AG + GG (UMOD) genotype have a greater risk (P=<0.0001, OR = 7.35, 95 % CI = 3.83-13.68) of developing a renal stone. The renal stone risk was persistent (P=<0.0002, OR = 2.44, 95 % CI = 1.52-3.86) when analyzed for the synergistic effect of risk genotypes of SPP1 (CT) and UMOD (GG) gene. Further, correlation analysis also confirmed the strong association between genetic variants and renal stone development.

CONCLUSION

Genetic variants of the SPP1 and UMOD genes were associated with renal stone disease. In the presence of risk genotype and hyperparathyroidism, hypercalciuria, and hyperoxaluria, the susceptibility to develop the renal stone disease risk gets modulated.

Physical activity can influence the relationship between ethylene oxide and risk of kidney stones: A cross-sectional study from the NHANES 2013-2016

Ethylene oxide (EO) is known to cause inflammatory damage, and suitable physical activity can reportedly affect the risk of kidney stones. In this study, we aimed to investigate the relationship between EO and kidney stones and whether physical activity can potentially influence the relationship between EO and kidney stones. Overall, 3,336 adult participants were included; of them, 330 (9.9%) had a self-reported history of kidney stones. Data were obtained from the National Health and Nutrition Examination Survey 2013-2016. Physical activity was calculated using metabolic equivalent, weekly frequency, and duration. Logistic regression and restricted cubic spline (RCS) curves were used to explore the association between physical activity, EO, and kidney stones. Dose-response curves from the RCS showed a nonlinear positive association between EO and kidney stones. Multivariate logistic regression analysis revealed an adjusted odds ratio (aOR) of 1.548 (95% confidence interval 1.123-2.135, P = 0.008) for the risk of kidney stones among participants in the highest quartile (Q4) group compared with those in the lowest quartile (Q1) group. Furthermore, compared to the Q1 group, the aOR for risk of kidney stones in the Q4 group was 1.326 in participants without physical activity, a decreased risk (aOR 1.239) in participants with low physical activity, and an increased risk (aOR 1.981) in those with high physical activity. This study suggests that EO is a risk factor for kidney stones and that suitable physical activity may moderate this relationship to some extent; however, excessive physical activity can exacerbate this relationship.

Vitamin D and Calcium Supplementation and Urolithiasis: A Controversial and Multifaceted Relationship

Patients with urolithiasis, and particularly those with hypercalciuria, frequently have a marked reduction of bone mineral content up to the levels of osteoporosis, with a significant increase in bone fracture risk. For these reasons, the indication to prescribe vitamin D and/or calcium supplementations is very frequent in such patients. On the other hand, both calcium supplementation, and even more vitamin D therapy, can worsen the risk of developing urolithiasis by increasing calcium, phosphate, and oxalate urinary excretion. Despite the clinical and practical relevance of this issue, the evidence on this topic is scarce and contradictory. Therefore, some concerns exist about how and whether to prescribe such supplements to a patient with a history of kidney stones. In this narrative review, we resume some pivotal pathophysiological concepts strictly related to the dealt topic, and we draw some considerations and personal opinions on the pros and cons of such prescriptions. Finally, we share with the reader our pragmatic algorithm for handling the urolithiasis risk in patients who have strong indications to be prescribed vitamin D and calcium supplementations.

Inflammation and kidney stones: cause and effect?

PURPOSE OF REVIEW

This short review is intended to highlight the potential role of inflammation as a key pathological driver, rather than a mere consequence, of nephrolithiasis. Although there is clearly a strong likelihood that the relationship is bidirectional, and that kidney stone-triggered inflammation can establish a vicious cycle of tissue injury and stone formation.

RECENT FINDINGS

These consist of data from both recent preclinical and clinical studies demonstrating the importance of inflammation in models of stone disease and in kidney tissue from patients with nephrolithiasis, and as a potential driver of disease recurrence and a suitable treatment target. In particular, the role of immune cells and their relationship to the NLRP3 inflammasome is becoming clearer, as well as the potential contribution to tissue injury and stone formation of the pro-inflammatory cytokines interleukin-1β and interleukin-18.

SUMMARY

This concept is not new and raises the possibility that targeting inflammation directly may prove to be a novel and suitable means of treatment for at least some types of kidney stone, and in certain clinical settings, both acutely and as prevention, especially in those patients experiencing recurrent stone episodes and/or who have a well defined metabolic cause such as uric acid or calcium oxalate stones.

Epidemiology of Kidney Stones

In the past two decades, major breakthroughs that improve our understanding of the pathophysiology and therapy of kidney stones (KS) have been lacking. The disease continues to be challenging for patients, physicians, and healthcare systems alike. In this context, epidemiological studies are striving to elucidate the worldwide changes in the patterns and the burden of the disease and identify modifiable risk factors that contribute to the development of kidney stones. Our expanding knowledge of the epidemiology of kidney stones is of paramount importance and largely upgrades the modern management of the disease. In this paper, we review the variables affecting prevalence and incidence, including age, gender, race, ethnicity, occupation, climate, geography, systemic diseases, diabetes, vascular disease, chronic kidney disease, and dietary risk factors relevant to kidney stones.

Network pharmacology and experimental validation to elucidate the pharmacological mechanisms of Bushen Huashi decoction against kidney stones

INTRODUCTION

Kidney stone disease (KS) is a complicated disease with an increasing global incidence. It was shown that Bushen Huashi decoction (BSHS) is a classic Chinese medicine formula that has therapeutic benefits for patients with KS. However, its pharmacological profile and mechanism of action are yet to be elucidated.

METHODS

The present study used a network pharmacology approach to characterize the mechanism by which BSHS affects KS. Compounds were retrieved from corresponding databases, and active compounds were selected based on their oral bioavailability (≥30) and drug-likeness index (≥0.18). BSHS potential proteins were obtained from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, whereas KS potential genes were obtained from GeneCards and OMIM, TTD, and DisGeNET. Gene ontology and pathway enrichment analysis were used to determine potential pathways associated with genes. The ingredients of BSHS extract were identified by the ultra-high-performance liquid chromatography coupled with quadrupole orbitrap mass spectrometry (UHPLC-Q/Orbitrap MS). The network pharmacology analyses predicted the potential underlying action mechanisms of BSHS on KS, which were further validated experimentally in the rat model of calcium oxalate kidney stones.

RESULTS

Our study found that BSHS reduced renal crystal deposition and improved renal function in ethylene glycol(EG)+ammonium chloride(AC)-induced rats, and also reversed oxidative stress levels and inhibited renal tubular epithelial cell apoptosis in rats. BSHS upregulated protein and mRNA expression of E2, ESR1, ESR2, BCL2, NRF2, and HO-1 in EG+AC-induced rat kidney while downregulating BAX protein and mRNA expression, consistent with the network pharmacology results.

DISCUSSION

This study provides evidence that BSHS plays a critical role in anti-KS via regulation of E2/ESR1/2, NRF2/HO-1, and BCL2/BAX signaling pathways, indicating that BSHS is a candidate herbal drug for further investigation in treating KS.

Prevalence and risk factors of kidney stone disease in population aged 40-70 years old in Kharameh cohort study: a cross-sectional population-based study in southern Iran

BACKGROUND

Kidney stone is the major cause of morbidity, and its prevalence is increasing in the world. This study aimed to assess the prevalence and risk factors of kidney stone in the adult population of southern Iran based on the data of the Kharameh Cohort Study.

METHODS

This cross-sectional study was conducted on 10,663 individuals aged 40-70 years old, using the baseline data of Kharamah cohort study, which started in 2014. Among all participants, 2251 individuals had a history of kidney stone. The participants' demographic characteristics, behavioral habits, and the history of underlying diseases were investigated. The crude and Age Standardized Prevalence Rate of kidney stones was calculated. Also, logistic regression was used to identify the predictors of kidney stone. To check the goodness of fit index of the model, we used the Hosmer-Lemeshow test. All analyses were performed in STATA software.

RESULTS

The prevalence of kidney stone was estimated 21.11%. Also, the Age Standardized Prevalence Rate in men and women was calculated 24.3% and 18.7%, respectively. The mean age of the participants was 52.15 years. Higher prevalence of kidney stone was seen in women aged 40-50 years (40.47%, p = 0.0001) and moderate level of social economic status (31.47%, p = 0.03), men with overweight (44.69%, p < 0.0001) and those in a very high level of social economic status (35.75%, p = 0.001). The results of multiple logistic regression showed that the chance of having kidney stone was 1.17 times higher in diabetic individuals, 1.43 times higher in hypertensive individuals, 2.21 times higher in individuals with fatty liver, and 1.35 times higher in individuals with overweight. The level of socio economic status, male sex, and age were the other factors related to kidney stone.

CONCLUSION

In this study, underlying diseases such as fatty liver, diabetes, and hypertension as well as age, male sex, overweight, and high social economic status were identified as important risk factors for kidney stone. Therefore, identifying individuals at risk of kidney stone and providing the necessary training can greatly help to reduce this disease. However, health policymakers should prepare preventive strategies to reduce the occurrence of kidney stone.

Epidemiology of Urolithiasis with Sex and Working Status Stratification Based on the National Representative Cohort in Republic of Korea

Background

This study aimed to estimate the annual prevalence and incidence of urolithiasis stratified by work status based on a large nationwide sample.

Methods

This study used data from the National Health Insurance Service-National Sample Cohort from 2002 to 2015. The prevalence and incidence of urolithiasis were estimated based on work status and gender stratification. The risk of urolithiasis among workers was calculated using age-standardized incidence ratio with stratification of work type.

Results

The prevalence of urolithiasis was significantly higher in workers than in non-workers, especially men, during the follow-up period. The total estimated number of urolithiasis cases was 41,086 and the overall incidence of urolithiasis was 0.3%. The age-standardized incidence ratio of urolithiasis was significantly higher among the total workers (1.14; 95% confidence interval, 1.13-1.16), self-employed workers (1.08; 95% confidence interval, 1.06-1.11), and paid workers (1.19; 95% confidence interval, 1.17-1.21) than among the non-working population.

Conclusions

Workers, especially paid workers and men, were vulnerable to urolithiasis. Further studies are required to investigate the effects of working conditions on urolithiasis.

Two independent modes of kidney stone suppression achieved by AIM/CD5L and KIM-1

The prevalence of kidney stones is increasing and its recurrence rate within the first 5 years is over 50%. No treatments that prevent the occurrence/recurrence of stones have reached the clinic. Here, we show that AIM (also called CD5L) suppresses stone development and improves stone-associated physical damages. The N-terminal domain of AIM associates with calcium oxalate crystals via charge-based interaction to impede the development of stones, whereas the 2nd and C-terminal domains capture the inflammatory DAMPs to promote their phagocytic removal. Accordingly, when stones were induced by glyoxylate in mice, recombinant AIM (rAIM) injection dramatically reduced stone development. Expression of injury molecules and inflammatory cytokines in the kidney and overall renal dysfunction were abrogated by rAIM. Among various negatively charged substances, rAIM was most effective in stone prevention due to its high binding affinity to crystals. Furthermore, only AIM was effective in improving the physical complaints including bodyweight-loss through its DAMPs removal effect. We also found that tubular KIM-1 may remove developed stones. Our results could be the basis for the development of a comprehensive therapy against kidney stone disease.

The circulating protein apoptosis inhibitor of macrophage (AIM) reduces kidney stone development and prevents build up, providing the basis for kidney stone disease therapy.

Dietary Risk Factors for Incident and Recurrent Symptomatic Kidney Stones

OBJECTIVE

To compare dietary factors between incident symptomatic stone formers and controls, and among the incident stone formers, to determine whether dietary factors were predictive of symptomatic recurrence.

PATIENTS AND METHODS

We prospectively recruited 411 local incident symptomatic kidney stone formers (medical record validated) and 384 controls who were seen at Mayo Clinic in Minnesota or Florida between January 1, 2009, and August 31, 2018. Dietary factors were based on a Viocare, Inc, food frequency questionnaire administered during a baseline in-person study visit. Logistic regression compared dietary risk factors between incident symptomatic stone formers and controls. Incident stone formers were followed up for validated symptomatic recurrence in the medical record. Cox proportional hazards models estimated risk of symptomatic recurrence with dietary factors. Analyses adjusted for fluid intake, energy intake, and nondietary risk factors.

RESULTS

In fully adjusted analyses, lower dietary calcium, potassium, caffeine, phytate, and fluid intake were all associated with a higher odds of an incident symptomatic kidney stone. Among incident stone formers, 73 experienced symptomatic recurrence during a median 4.1 years of follow-up. Adjusting for body mass index, fluid intake, and energy intake, lower dietary calcium and lower potassium intake were predictive of symptomatic kidney stone recurrence. With further adjustment for nondietary risk factors, lower dietary calcium intake remained a predictor of recurrence, but lower potassium intake only remained a predictor of recurrence among those not taking thiazide diuretics or calcium supplements.

CONCLUSION

Enriching diets in stone formers with foods high in calcium and potassium may help prevent recurrent symptomatic kidney stones.

Lipidomics characterization of the lipid metabolism profiles in a cystinuria rat model: Precalculus damage in the kidney of cystinuria

Cystinuria is a genetic disorder of cystine transport, including defective protein b^0,+AT (encoded by SLC7A9), and/or rBAT (encoded by SLC3A1). Patients present hyperexcretion of cystine in the urine, recurrent cystine lithiasis, and progressive decline in kidney function. Moreover, heterodimer transport is defective. To date, little omics data are accessible regarding this metabolic disease caused by membrane proteins. Since membrane function is closely related to changes in the lipidome, we decided to explore the changes in kidney tissue of a self-established cystinuria rat model by performing lipidomic analysis by LC-MS/MS. Our results demonstrated that Slc7a9 deficiency changed the lipid profile of the renal cortex and induced vital modifications in the lipidome, including major alterations in ChE, LPA, and PA. Among those alterations, this lipidomic study highlights the lipid changes that participate in inflammatory responses during cystinuria. As a result, lipid research, perhaps has great potential, for it may lead to the identification of novel therapeutic targets for the prevention and treatment of cystinuria.

Kidney Stones, Proteinuria and Renal Tubular Metabolic Acidosis: What Is the Link?

Kidney stone disease represents a rare cause of chronic kidney disease (2−3%) but has severe clinical consequences. Type 1 renal tubular acidosis is a strong lithogenic condition mainly related to primary Sjögren syndrome. This study aimed to illustrate an unusual presentation of Sjögren syndrome to improve the knowledge about rare kidney stone diseases, and to provide clues for the diagnostic approach in this specific condition. We report the case of a 35-year-old Indian woman with severe nephrocalcinosis and chronic kidney disease with tubular proteinuria who presented for metabolic assessment. We found advanced chronic kidney disease, low serum bicarbonate, permanent alkaline urine with pH at ~7.1, and severe hypocitraturia corresponding to type 1 renal tubular acidosis. The erythrocyte sedimentation rate was high. Serological screening for HAV, HBV, HCV, HIV, EBV was negative and complement was normal. Autoimmune screening showed antinuclear antibodies (>1/1.280) with anti-SSA, anti-SSA/Ro52 and anti-SSB antibodies. Genetic testing excluded an inherited cause of renal tubular acidosis. A renal biopsy showed moderate chronic tubulo-interstitial nephritis without any glomerular involvement. Primary Sjögren syndrome with significant renal involvement was considered, and corticosteroids were then subsequently initiated in combination with potassium citrate with vitamin D substitution. Only partial improvement was observed in electrolytes disturbance. After 15 months, her renal function remained stable. In conclusion, nephrocalcinosis could be the first manifestation of severely impacting diseases such as primary Sjögren syndrome. Chronic kidney disease, bilateral nephrocalcinosis, and metabolic acidosis can be linked through type 1 renal tubular acidosis. Therefore, autoimmune screening for Sjögren syndrome should be considered in such cases.

The long-term renal effects of short periods of unilateral ureteral obstruction

The response of the kidney and its recovery following unilateral ureteral obstruction (UUO) depend on several factors including the duration of obstruction, the species involved and the age of the individual. In neonates, there is compelling evidence to indicate that even short periods of reversible UUO might lead to long-term renal impairment. In adults, the glomerular filtration rate returns to baseline values soon after the release of short periods of UUO. Despite this return to normal, experimental data have demonstrated that short periods of reversible UUO could lead to long-term renal functional alterations including tubular atrophy, interstitial fibrosis and urinary albumin leakage in addition to alterations in pro-inflammatory and pro-fibrotic cytokines. The concentrating ability of the kidney and its response to stimuli such as renal nerve stimulation and physiological doses of angiotensin-II were also shown to be affected at least in the intermediate-term following UUO reversal. In humans, epidemiological studies have also demonstrated a clear association between long-term renal impairment and ureteral obstruction. However, in clinical studies, it is usually difficult to precisely determine the degree and the time of onset of ureteral obstruction and more studies are required in this field. In conclusion, the available experimental and clinical data indicate that even short periods of UUO can cause long-term renal dysfunction. These findings might have clinical implications related to the early intervention following acute onset of UUO and to the need for long-term monitoring of renal functions particularly in patients with underlying chronic renal disease.

Clinical and Kidney Structural Characteristics of Living Kidney Donors With Nephrolithiasis and Their Long-term Outcomes

Nephrolithiasis in living kidney donors is concerning due to the potential impact on long-term postdonation kidney function.

Impact of acute kidney injury on long-term adverse outcomes in obstructive uropathy

Obstructive uropathy is known to be associated with acute kidney injury (AKI). This study aimed to investigate the etiologies, clinical characteristics, consequences and also assess the impact of AKI on long-term outcomes. This multicenter, retrospective study of 1683 patients with obstructive uropathy who underwent percutaneous nephrostomy (PCN) analyzed clinical characteristics, outcomes including progression to end-stage kidney disease (ESKD), overall mortality, and the impact of AKI on long-term outcomes. Obstructive uropathy in adults was most commonly caused by malignancy, urolithiasis, and other causes. AKI was present in 78% of the patients and was independently associated with preexisting chronic kidney disease (CKD). Short-term recovery was achieved in 56.78% after the relief of obstruction. ESKD progression rate was 4.4% in urolithiasis and 6.8% in other causes and older age, preexisting CKD, and stage 3 AKI were independent factors of progression. The mortality rate (34%) was highly attributed to malignant obstruction (52%) stage 3 AKI was also an independent predictor of mortality in non-malignant obstruction. AKI is a frequent complication of adult obstructive uropathy. AKI negatively affects long-term kidney outcomes and survival in non-malignant obstructions. A better understanding of the epidemiology and prognostic factors is needed for adult obstructive uropathy.

Oxalate Alters Cellular Bioenergetics, Redox Homeostasis, Antibacterial Response, and Immune Response in Macrophages

Individuals with calcium oxalate (CaOx) kidney stones can have secondarily infected calculi which may play a role in the development of recurrent urinary tract infection (UTI). Uropathogenic Escherichia coli (UPEC) is the most common causative pathogen of UTIs. Macrophages play a critical role in host immune defense against bacterial infections. Our previous study demonstrated that oxalate, an important component of the most common type of kidney stone, impairs monocyte cellular bioenergetics and redox homeostasis. The objective of this study was to investigate whether oxalate compromises macrophage metabolism, redox status, anti-bacterial response, and immune response. Monocytes (THP-1, a human monocytic cell line) were exposed to sodium oxalate (soluble oxalate; 50 µM) for 48 hours prior to being differentiated into macrophages. Macrophages were subsequently exposed to calcium oxalate crystals (50 µM) for 48 hours followed by UPEC (MOI 1:2 or 1:5) for 2 hours. Peritoneal macrophages and bone marrow-derived macrophages (BMDM) from C57BL/6 mice were also exposed to oxalate. THP-1 macrophages treated with oxalate had decreased cellular bioenergetics, mitochondrial complex I and IV activity, and ATP levels compared to control cells. In addition, these cells had a significant increase in mitochondrial and total reactive oxygen species levels, mitochondrial gene expression, and pro-inflammatory cytokine (i.e. Interleukin-1β, IL-1β and Interleukin-6, IL-6) mRNA levels and secretion. In contrast, oxalate significantly decreased the mRNA levels and secretion of the anti-inflammatory cytokine, Interleukin-10 (IL-10). Further, oxalate increased the bacterial burden of primary macrophages. Our findings demonstrate that oxalate compromises macrophage metabolism, redox homeostasis, and cytokine signaling leading to a reduction in anti-bacterial response and increased infection. These data highlight a novel role of oxalate on macrophage function.

The new patterns of nephrolithiasis: What has been changing in the last millennium?

Nephrolithiasis has been increasing over the last millennium. Although early epidemiologic studies have shown that kidney stones were two to three times more frequent in males than in females, recent reports have suggested that this rate is decreasing. In parallel a dramatic increase of nephrolithiasis has also been observed among children and adolescents. Furthermore, epidemiologic studies have shown a strong association between metabolic syndrome (Mets) traits and kidney stone disease. Patients with hypertension have a higher risk of stone formation and stone formers are predisposed to develop hypertension compared to the general population. An incidence of nephrolithiasis greater than 75% has been shown in overweight and obese patients compared to those of normal weight. It has also been reported that a previous diagnosis of diabetes mellitus increases the risk of future nephrolithiasis. Additionally, an association between metabolic syndrome and uric acid stone formation has been clearly recognized. Furthermore, 24-h urinary metabolic abnormalities have been decreasing among patients with nephrolithiasis over the last decades. Finally, nephrolithiasis could cause chronic kidney disease (CKD) and end stage renal disease (ESRD), especially in women and overweight patients. According to these observations, a better understanding of these new features among stone former patients may be required. Hence, the recognition and the correction of metabolic disorders could help not only to reduce the primary disease, but also stone recurrence.

Maternal and neonatal outcomes of pregnancy complicated by urolithiasis: a systematic review and meta-analysis

BACKGROUND

The effect of urolithiasis on pregnancy-related outcomes remains unknown. The aim of this study was to determine the risk of adverse maternal and neonatal outcomes.

METHODS

We searched PubMed, Embase, and the Cochrane Library through December 2020 for studies reporting on adverse maternal and neonatal outcomes in patients with urolithiasis. Risk ratios (ORs) with 95% confidence intervals (CIs) were calculated for these outcomes in pregnant mothers with urolithiasis and compared to healthy controls.

RESULTS

Eight studies comprising 26,577 mothers with urolithiasis were included in our analysis. Preterm birth (OR = 1.63; 95% CI 1.37-1.95, p < 0.001) or very preterm birth risk (OR = 1.49, 95% CI 1.06-2.11, p = 0.02) was more common in patients with urolithiasis compared to healthy controls. Mothers with urolithiasis had an increased incidence of preeclampsia (OR = 1.75, 95% CI 1.33-2.3, p < 0.001), hypertension (OR = 2.97, 95% CI 1.31-6.71, p = 0.009), caesarean section (OR 1.31, 95% CI 1.11-1.55, p = 0.001), and gestational diabetes mellitus (OR 1.84, 95% CI 1.37-2.46, p < 0.001).

CONCLUSION

Patients with urolithiasis may be at increased risk of developing adverse maternal or neonatal outcomes.

Incidence and Characteristics of Kidney Stones in Patients on Ketogenic Diet: A Systematic Review and Meta-Analysis

Very-low-carbohydrate diets or ketogenic diets are frequently used for weight loss in adults and as a therapy for epilepsy in children. The incidence and characteristics of kidney stones in patients on ketogenic diets are not well studied. Methods: A systematic literature search was performed, using MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews from the databases’ inception through April 2020. Observational studies or clinical trials that provide data on the incidence and/or types of kidney stones in patients on ketogenic diets were included. We applied a random-effects model to estimate the incidence of kidney stones. Results: A total of 36 studies with 2795 patients on ketogenic diets were enrolled. The estimated pooled incidence of kidney stones was 5.9% (95% CI, 4.6–7.6%, I2 = 47%) in patients on ketogenic diets at a mean follow-up time of 3.7 +/− 2.9 years. Subgroup analyses demonstrated the estimated pooled incidence of kidney stones of 5.8% (95% CI, 4.4–7.5%, I2 = 49%) in children and 7.9% (95% CI, 2.8–20.1%, I2 = 29%) in adults, respectively. Within reported studies, 48.7% (95% CI, 33.2–64.6%) of kidney stones were uric stones, 36.5% (95% CI, 10.6–73.6%) were calcium-based (CaOx/CaP) stones, and 27.8% (95% CI, 12.1–51.9%) were mixed uric acid and calcium-based stones, respectively. Conclusions: The estimated incidence of kidney stones in patients on ketogenic diets is 5.9%. Its incidence is approximately 5.8% in children and 7.9% in adults. Uric acid stones are the most prevalent kidney stones in patients on ketogenic diets followed by calcium-based stones. These findings may impact the prevention and clinical management of kidney stones in patients on ketogenic diets.

Trends in the prevalence of kidney stones in the United States from 2007 to 2016

The overall prevalence of kidney stones (KS) in the US rose from 3.2% in 1980 to 10.1% in 2016, but the trends in important subgroups have not been reported. We examined the prevalence trends of KS in subgroups of age, sex and race in the US and identified relevant laboratory factors associated with a history of KS using National Health and Nutrition Examination Survey (NHANES) data. We conducted a cross-sectional study among 28,209 US adults aged ≥ 20 years old in the NHANES from 2007 to 2016. We calculated the prevalence of a self-reported history of KS by using weights and standardized to the 2010 US Census population. We also compared relevant laboratory values according to the history of KS. The prevalence of KS decreased from 8.7% in 2007-2008 to 7.2% in 2011-2012 but then increased to 9.0% in 2013-2014 and 10.1% in 2015-2016. However, the overall prevalence of KS increased over 2007-2016 (p-trend = 0.02). Prevalence of KS among men was higher than women. Among men aged 20-79, there were significant quadratic trends in the prevalence of KS. Whereas, the prevalence of KS increased as a linear trend among women aged 20-59 years over 2007-2016. There were no consistent trends in the prevalence of KS by race. The prevalence trend of KS among non-Hispanic whites was 9.8% from 2007 to 2010 then dropped to 7.9% in 2011-2012 and increased to 10.6% in 2013-2014 and 12.1% in 2015-2016. A similar trend was also observed among non-Hispanic blacks. Among Hispanic, the prevalence of KS was 7.6% in 2007-2008 and 7.4% in 2009-2010 and then fluctuated over the next several time periods. For non-Hispanic Asians, the range was 4.4-4.6%. Regarding relevant laboratory factors, after adjusting for sex, race, age, BMI, smoking status, alcohol drinking, history of diabetes and gout, urine albumin-creatinine ratio and serum osmolality were independently associated with the history of KS in women and men. In conclusion, there was substantial variability in KS prevalence across individual 2-year time periods. This variation of period-specific prevalence values emphasizes the importance of looking at long-term trends and using more than a single 2-year cycle in analyses to increase the precision of the estimate. However, there was an overall increase in the prevalence of KS over 2007-2016.

Fu-Fang-Jin-Qian-Cao herbal granules protect against the calcium oxalate-induced renal EMT by inhibiting the TGF-β/smad pathway

CONTEXT

Nephrolithiasis is a major public health problem worldwide and Fu-Fang-Jin-Qian-Cao granules (FFJQC) is a traditional Chinese herbal formula that is used to treat nephrolithiasis. The main component of nephrolithiasis is calcium oxalate (CaOx) and the epithelial-mesenchymal transition (EMT) shown to play a crucial role in CaOx-induced kidney injury. However, the mechanism underlying the therapeutic effect of FFJQC on the CaOx-induced renal EMT is unknown.

OBJECTIVE

This study explores the therapeutic benefits and mechanism of FFJQC in oxalate-induced kidney injury.

MATERIALS AND METHODS

60 male C57BL/6 mice were used in this experiment and divided into 6 groups. A mouse kidney stone model was created by intraperitoneal injection of glyoxylate at a dose of 100 mg/kg for 6 days. The standardized FFJQC was used to treat mouse crystal kidney injury by gavage at 1.35 and 2.7 g/kg, respectively. Western blotting and immunostaining for E-cadherin, cytokeratin 18 (CK18), vimentin, smooth muscle α-actin (α-SMA) and transforming growth factor β (TGF-β)/Smad pathway were conducted on renal tissues.

RESULTS

Following CaOx-induced kidney injury, the levels of E-cadherin and CK18 in kidney decreased, while vimentin and α-SMA levels increased. The FFJQC treatment increased the levels of E-cadherin and CK18 and decreased vimentin and α-SMA levels in varying degrees. What's more, the FFJQC reduced the expression of CaOx-induced fibrosis marker collagen II.

CONCLUSION

FFJQC alleviated the CaOx-induced renal EMT and fibrosis by regulating TGF-β/smad pathway. Therefore, the FFJQC is an important traditional Chinese medicine for the treatment of CaOx-induced renal injury and fibrosis.

An ensemble of deep neural networks for kidney ultrasound image classification

BACKGROUND AND OBJECTIVE

Chronic kidney disease is a worldwide health issue which includes not only kidney failure but also complications of reduced kidney functionality. Cyst formation, nephrolithiasis or kidney stone, and renal cell carcinoma or kidney tumor are the common kidney disorders which affects the functionality of kidneys. These disorders are typically asymptomatic, therefore early and automatic diagnosis of kidney disorders are required to avoid serious complications.

METHODS

This paper proposes an automatic classification of B-mode kidney ultrasound images based on the ensemble of deep neural networks (DNNs) using transfer learning. The ultrasound images are usually affected by speckle noise and quality selection in the ultrasound image is based on perception-based image quality evaluator score. Three variant datasets are given to the pre-trained DNN models for feature extraction followed by support vector machine for classification. The ensembling of different pre-trained DNNs like ResNet-101, ShuffleNet, and MobileNet-v2 are combined and final predictions are done by using the majority voting technique. By combining the predictions from multiple DNNs the ensemble model shows better classification performance than the individual models. The presented method proved its superiority when compared to the conventional and DNN based classification methods. The developed ensemble model classifies the kidney ultrasound images into four classes, namely, normal, cyst, stone, and tumor.

RESULTS

To highlight effectiveness of the proposed approach, the ensemble based approach is compared with the existing state-of-the-art methods and tested in the variants of ultrasound images like in quality and noisy conditions. The presented method resulted in maximum classification accuracy of 96.54% in testing with quality images and 95.58% in testing with noisy images. The performance of the presented approach is evaluated based on accuracy, sensitivity, and selectivity.

CONCLUSIONS

From the experimental analysis, it is clear that the ensemble of DNNs classifies the majority of images correctly and results in maximum classification accuracy as compared to the existing methods. This automatic classification approach is a supporting tool for the radiologists and nephrologists for precise diagnosis of kidney diseases.

Practice patterns of kidney stone management across European and non-European centers: an in-depth investigation from the European Renal Stone Network (ERSN)

Rationale and objective

Kidney stones are a common condition in the general population, however, high-quality evidence for its management is scarce. We propose the creation of an international network with the aim of sharing practice patterns and patient data towards an improvement of our knowledge of the disease.

Study design

Cross-sectional survey.

Setting and participants

An online survey was circulated through several scientific societies. Items were grouped into six domains. Each center’s overall score (OS) was also calculated.

Analytical approach

Chi square and Mann–Whitney tests were performed for differences across centers.

Results

The countries that contributed most were Italy (8.6%), Turkey (6.6%), France and Spain (6.1%). Some type of nutritional work-up was implemented in 62% of centers. A DEXA scan was performed by 46% of centers, whereas some kind of acidification test was performed by 25% of centers. Most centers (80%) implemented blood investigations at least at baseline. With regard to 24-h urine exams, 7 out of 16 were performed by at least 50% of centers. Information on stone composition was collected by 58% of centers. The OS was significantly higher among higher-volume centers compared with lower-volume centers (p = 0.002). Significant differences between EU and non-EU centers were found.

Limitations

Cross-sectional design; no validation on information.

Conclusions

Our survey highlights the potential for the creation of a network of centers that could share information in a common database for observational research and for enrollment of patients in interventional trials.

Electronic supplementary material

The online version of this article (10.1007/s40620-020-00854-6) contains supplementary material, which is available to authorized users.

Chronic kidney disease and kidney stones

PURPOSE OF REVIEW

Both chronic kidney disease (CKD) and kidney stones are major public health problems, which are closely interrelated. Recurrent kidney stones predispose to CKD although CKD seems to decrease risk of further kidney stone formation. Herein, we review new information of this interrelationship.

RECENT FINDINGS

Several epidemiological studies in the past have shown an association between history of kidney stones and risk for CKD and CKD progression. Recent literature supports this concept and it is reviewed in this article. The issue of whether CKD protects against new kidney stone formation remains unsettled and there is no recent literature addressing it. In relation to stone risk factors in CKD, there are several interesting new articles that discuss mechanisms of hypocitraturia in early CKD before overt metabolic acidosis. Since hypocitraturia is an important risk factor for kidney stone formation we addressed these new data in detail. There are also new data supporting urinary oxalate excretion as a predictor of CKD progression.

SUMMARY

It seems clear that recurrent kidney stones should be avoided not only because of their immediate clinical manifestations but also because of their long-term predisposition to CKD progression. Mechanisms leading to hypocitraturia in early CKD still remain controversial.

Association Between Serum Magnesium and the Prevalence of Kidney Stones: a Cross-sectional Study

Kidney stones, a painful and costly disease, have become a public health problem worldwide. The aim of this study was to evaluate the association between serum magnesium levels and the prevalence of kidney stones in a large population context. This study was conducted in Xiangya Hospital, Central South University in Changsha, Hunan, China, between October 2013 and December 2015. A total of 6228 subjects aged ≥ 18 years old were included. Kidney stones were diagnosed by (1) direct visualisation of stone(s) on the abdominal ultrasound examination, and (2) presence of stone(s) with a diameter ≥ 4 mm. The chemiluminescence method was used to measure the serum magnesium concentration. The association between serum magnesium and the prevalence of kidney stones was evaluated using logistic and spline regression in a cross-sectional study. The prevalence of kidney stones was 6.1% (7.5% in men and 4.2% in women). Compared with the lowest quartile, the crude odds ratio for kidney stones was 0.62 (95% CI 0.46-0.85) for the highest quartile of serum magnesium, and there was an inverse dose-response relationship (P for trend = 0.038). Similar results were observed for men and women separately. The findings were not materially altered by adjustment for potential confounders. In conclusion, subjects with relatively lower levels of serum magnesium, even though within the normal range, were subject to a higher prevalence of kidney stones in a dose-response relationship manner, indicating that magnesium may play a certain role in the prevention or treatment of kidney stones.

Characteristics of the urinary microbiome in kidney stone patients with hypertension

Background

Kidney stone disease (KSD) is more common in individuals with hypertension (HTN) than in individuals with normotension (NTN). Urinary dysbiosis is associated with urinary tract disease and systemic diseases. However, the role of the urinary microbiome in KSD complicated with HTN remains unclear.

Methods

This study investigated the relationship between the pelvis urinary microbiome and blood pressure (BP) in patients with KSD co-occurring with HTN (KSD-HTN) and healthy controls (HC) by conducting 16S rRNA gene sequencing of bacteria in urine samples. The urine samples were collected (after bladder disinfection) from 50 patients with unilateral kidney calcium stones and NTN (n = 12), prehypertension (pHTN; n = 11), or HTN (n = 27), along with 12 HCs.

Results

Principal coordinates analysis showed that there were significant differences in the urinary microbiomes not only between KSD patients and HCs but also between KSD-pHTN or KSD-HTN patients and KSD-NTN patients. Gardnerella dominated in HCs, Staphylococcus dominated in KSD-NTN patients and Sphingomonas dominated in both KSD-pHTN and KSD-HTN patients. The abundance of several genera including Acidovorax, Gardnerella and Lactobacillus was correlated with BP. Adherens junction and nitrogen and nucleotide metabolism pathways, among others, were associated with changes in BP.

Conclusions

The findings suggest that patients with KSD complicated with HTN have a unique urinary microbiome profile and that changes in the microbiome may reflect disease progression and may be useful to monitor response to treatments.

Neurogenic bladder: management of the severely impaired patient with complete urethral destruction: ileovesicostomy, suprapubic tube drainage or urinary diversion-is one treatment modality better than another?

Background

Management of the severely impaired patient (pt) with a neurogenic bladder (NGB) and complete urethral destruction employs three therapeutic options; bladder neck closure (BNC) with ileovesicostomy, BNC with suprapubic tube (SPT) placement or in pts with an end-stage bladder, cystectomy with enteric conduit diversion. This paper was performed to test the hypothesis that pts managed with an ileovesicostomy would have the best long-term prognosis.

Methods

Patients with a NGB and complete urethral destruction managed between 1986-2018 were reviewed. Three treatment populations were assessed, pts treated with BNC with ileovesicostomy, BNC with SPT placement or cystectomy with enteric conduit diversion. A minimal follow-up interval of 2 years was necessary to be entered into the study. The number of uroseptic episodes, development of urolithiasis, the onset of new renal scars, ≥ stage 3 chronic renal failure, or need for additional surgery were recorded. Statistical evaluations used either chi-squared contingency table analysis, Fisher's exact 2-tailed tests, or Kaplan-Meier curve analysis where indicated. P values of <0.05 were considered significant.

Results

Ten pts were managed by cystectomy, and enteric conduit, 17 by BNC and ileovesicostomy and 21 by BNC and SPT placement, median follow up of 8 yrs (range, 2-30 yrs). No significant differences between the three groups regarding the development of urolithiasis (30%, 3/10 pts; 53%, 9/17 pts; 52%, 11/21 pts; respectively), new onset of renal scarring (30%, 6/20 kidneys; 41%, 14/34 kidneys; 45%, 19/42 kidneys; respectively) or stage 3 chronic renal failure (40%, 4/10 pts; 47%, 8/17 pts; 24%, 5/21 pts; respectively. However, the number of hospitalizations for uroseptic episodes significantly increased in patients managed with an ileal conduit (60%, 6/10 pts) and ileovesicostomy (82%; 14/17 pts) compared to those maintained with a SPT (29%, 6/21 pts) P=0.025 and 0.006, respectively. When evaluating the need for delayed surgical intervention due to either urolithiasis or other complications, a total of 50% (5/10 pts) of the patients managed by an ileal conduit, 88% (15/17 pts) of the ileovesicostomy and 52% (11/21 pts) of the patients with a SPT required additional operations. In essence, significantly more pts undergoing BNC and ileovesicostomy required delayed surgical interventions for complications arising from the surgery compared to patients managed with either a cystectomy and ileal conduit (P=0.0285) or BNC and SPT placement (P=0.0180).

Conclusions

In severely impaired pts with a NGB and urinary outlet destruction, BNC and ileovesicostomy are associated with a significantly increased incidence of urosepsis and late surgical complications that required operative intervention compared to alternative treatments. This finding has resulted in the abandonment of the ileovesicostomy from our surgical armamentarium.

Differences in national and international guidelines regarding use of kidney stone formers as living kidney donors

PURPOSE OF REVIEW

Traditionally, nephrolithiasis was considered a relative contraindication to kidney donation because of a risk of recurrent stones in donors and adverse stone-related outcomes in recipients. However, the scarcity of organs has driven the transplant community to re-examine and broaden selection criteria for living donors with stones. In this review, we summarize and contrast the guidelines published by various prominent national and international societies on this topic.

RECENT FINDINGS

Although recent iterations of living donor guidelines are less stringent with respect to nephrolithiasis than those published in the 1990s, there is little consensus among national and international transplant society guidelines regarding selection criteria for potential kidney donors with nephrolithiasis.

SUMMARY

The lack of evidence-based guidelines deters transplant centers from implementing selection criteria to accept donors with nephrolithiasis and discourages studies of outcomes in donors with nephrolithiasis and their recipients. In addition to drawing attention to the disparities in prevailing guidelines, we put forth several questions that must be answered before generalizable criteria for selection of donor with nephrolithiasis can be developed.

Automatic detection of calcium phosphate deposit plugs at the terminal ends of kidney tubules

Kidney stones are a common urologic condition with a high amount of recurrence. Recurrence depends on a multitude of factors the incidence of precursors to kidney stones, plugs, and plaques. One method of characterising the stone precursors is endoscopic assessment, though it is manual and time-consuming. Deep learning has become a popular technique for semantic segmentation because of the high accuracy that has been demonstrated. The present Letter examined the efficacy of deep learning to segment the renal papilla, plaque, and plugs. A U-Net model with ResNet-34 encoder was tested; the Letter examined dropout (to avoid overtraining) and two different loss functions (to address the class imbalance problem. The models were then trained in 1666 images and tested on 185 images. The Jaccard-cross-entropy loss function was more effective than the focal loss function. The model with the dropout rate 0.4 was found to be more effective due to its generalisability. The model was largely successful at delineating the papilla. The model was able to correctly detect the plaques and plugs; however, small plaques were challenging. Deep learning was found to be applicable for segmentation of an endoscopic image for the papilla, plaque, and plug, with room for improvement.

Risk Factors for End-Stage Renal Failure Among Patients on Hemodialysis in Aljomhory Hospital, Sa'adah Governorate, Yemen: Hospital-Based Case-Control Study

BACKGROUND

More than 16% of the world's population is affected by chronic kidney disease, and these people are at the highest risk of developing end-stage renal failure (ESRF).

OBJECTIVE

The aim of this study was to determine the risk factors of ESRF in Sa'adah Governorate in Yemen.

METHODS

A hospital-based case-control study (86 cases and 263 controls) was conducted in the Aljomhory Hemodialysis Center in Sa'adah city, Yemen. Patients with ESRF who attended the hemodialysis center in Aljomhory Hospital in Sa'adah City from January 1 to February 15, 2016, were included. Control participants were healthy persons without end-stage renal disease (ESRD) who attended Aljomhory Hospital as outpatients' relatives during the study period.

RESULTS

A total of 86 cases and 263 controls were included in this study. The mean age was 43.3 (SD 17.7) years for cases and 32.3 (SD 13.0) years for controls. In univariate analysis of factors associated with ESRD, patients aged≥40 years were 3.7 times more likely to have ESRD than younger patients. The odds of ESRD was higher among men than women. Illiteracy was significantly associated with higher odds of ESRD. Hypertension (odds ratio [OR]=8.34), diabetes (OR=3.07), cardiovascular diseases (OR=12.71), presence of urinary stones (OR=21.87), recurrent urinary tract infection (OR=9.64), cigarette smoking (OR=2.44), and shammah use (OR=6.65) were significantly associated with higher odds of ESRD. Hypertension (OR=6.68), urinary stones (OR=16.08), and recurrent urinary tract infection (OR=8.75) remained significantly associated with ERD in multivariate analysis.

CONCLUSIONS

Hypertension, presence of urinary stones, and recurrent urinary tract infections were significantly associated with ESRF development. Improving the management of hypertension and designing suitable interventions to control problems of the urinary tract would help reduce ESRD prevalence.

Impact of potassium citrate on urinary risk profile, glucose and lipid metabolism of kidney stone formers in Switzerland

Background

Hypocitraturia and hypercalciuria are the most prevalent risk factors in kidney stone formers (KSFs). Citrate supplementation has been introduced for metaphylaxis in KSFs. However, beyond its effects on urinary parameters and stone recurrence, only a few studies have investigated the impact of citrate on other metabolic pathways such as glucose or lipid metabolism.

Methods

We performed an observational study using data from the Swiss Kidney Stone Cohort. Patients were subdivided into two groups based on treatment with potassium citrate or not. The outcomes were changes of urinary risk parameters, haemoglobin A1c (HbA_1c), fasting glucose, cholesterol and body mass index (BMI).

Results

Hypocitraturia was present in 19.3% of 428 KSFs and potassium citrate was administered to 43 patients (10.0%) at a mean dosage of 3819 ± 1796 mg/day (corresponding to 12.5 ± 5.9 mmol/ day). Treatment with potassium citrate was associated with a significantly higher mean change in urinary citrate (P = 0.010) and urinary magnesium (P = 0.020) compared with no potassium citrate treatment. Exogenous citrate administration had no effect on cholesterol, fasting glucose, HbA_1c and BMI. Multiple linear regression analysis demonstrated no significant association of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂ D₃] levels with urinary citrate excretion.

Conclusion

Potassium citrate supplementation in KSFs in Switzerland resulted in a beneficial change of the urinary risk profile by particularly increasing anti-lithogenic factors. Fasting glucose, HbA_1c, cholesterol levels and BMI were unaffected by potassium citrate therapy after 3 months, suggesting that potassium citrate is safe and not associated with unfavourable metabolic side effects. Lastly, 1,25(OH)₂ D₃ levels were not associated with urinary citrate excretion.

Hypertension and renal impairment in patients with cystinuria: findings from a specialist cystinuria centre

Higher blood pressures (mean systolic difference 16.8 mmHg) when compared to matched individuals are already reported in patients with calcium urolithiasis. We present the prevalence of hypertension and renal impairment in patients with cystinuria from our specialist single centre. We analysed our prospective database of adult patients with cystinuria who attend our cystinuria service. This included details of the medical and operative management of their disease. Descriptive statistics were used to analyse and present the data. 120 patients were included with a median age of 40 (19-76) years, 66 were male (55%) and 54 were female (45%). 54/120 patients (45%) were taking medications to prevent stone formation. 78% (94/120) patients reported having undergone one or more stone-related procedure. 59% (55/94) of these having required at least one PCNL or open procedure during their lifetime. Prevalence of hypertension was 50.8% (61/120), and double in males compared to females (62.1% vs. 37.0%, P = 0.0063). Mean baseline creatinine was 88.2 (49-153) µmol/l and eGFR was 77.6 (32-127) ml/min/1.73 m2. When categorized by CKD stage, only 24.6% (27% vs. 21%, M vs. F) patients had normal renal function (being an eGFR > 89 ml/min/1.73 m2). 57.6% patients were CKD stage 2 and 17.8% CKD stage 3. Females had a slightly greater incidence of renal impairment. All patients who have previously undergone a nephrectomy (n = 10) or have a poorly functioning kidney (n = 19) have renal impairment (CKD stage 2 or 3). Incidence of hypertension in patients with cystinuria is 51%, with a male preponderance. Only 25% of patients with cystinuria have normal renal function. This highlights the long-term cardiovascular and renal risks that the metabolic effects of cystinuria pose, in addition to the challenges of managing recurrent urolithiasis in a young population.

Pioglitazone decreased renal calcium oxalate crystal formation by suppressing M1 macrophage polarization via the PPAR-γ-miR-23 axis

Interaction of pioglitazone (PGZ) and macrophages (Mps) in renal crystal formation remains unclear. In the present study, we investigated the possible mechanisms involved with Mps of PGZ in suppressing renal crystal formation. Crystal formation in the mouse kidney was detected using polarized light optical microscopy and Pizzolato staining. Gene expression was detected by Western blot analysis, quantitative RT-PCR, immunohistochemistry, immunofluorescence, and ELISA. Mp phenotypes were identified by flow cytometric analysis. Cell apoptosis was detected with TUNEL assay, and tubular injury was detected with periodic acid-Schiff staining. Interaction of peroxisome proliferator-activated receptor (PPAR)-γ and promoter was determined by chromatin immunoprecipitation assay. Luciferase reporter assay was performed to authenticate target genes of miRNA-23 (miR-23). Recombinant adenovirus was used to elucidate the role of miR-23 in vivo. Renal crystal formation, inflammation, tubular injury, and cell apoptosis were significantly marked in glyoxylic acid-treated groups and significantly decreased in PGZ-treated groups. PGZ significantly reduced Mp infiltration and M1 Mp polarization in the kidney. In vitro, PGZ shifted crystal-stimulated M1-predominant Mps to M2-predominant Mps, which were anti-inflammatory. PPAR-γ could directly bind to one PPAR-γ regulatory element in the promoter of pre-miR-23 to promote expression of miR-23 in Mps. We identified two downstream target genes of miR-23, interferon regulatory factor 1 and Pknox1. Moreover, miR-23 decreased crystal deposition, M1 Mp polarization, and injury in the kidney. This study has proven that PGZ decreased renal calcium oxalate crystal formation and renal inflammatory injury by suppressing M1 Mp polarization through a PPAR-γ-miR-23-interferon regulatory factor 1/Pknox1 axis. PGZ is liable to be a potential therapeutic medicine for treating urolithiasis.

New-onset metabolic risk factors and the incidence of kidney stones: a prospective cohort study

OBJECTIVE

To examine the association of kidney stones with new-onset hypertension, diabetes and obesity.

PARTICIPANTS AND METHODS

This prospective cohort study included participants in the Qingdao Port Cardiovascular Health Study who were aged ≥18 years and had abdominal ultrasonography results in 2013 that were negative for kidney stones. Multivariable Cox regression models with time-dependent covariates were used to estimate the effects of new-onset hypertension, diabetes and obesity on the incidence of kidney stones.

RESULTS

There were 9667 participants without kidney stones in 2013 (mean age 46.2 years; 75.6% men). During a mean (range) follow-up of 33.5 (6-42) months, 676 (7.0%) incident cases of kidney stones were identified. Kidney stones were more frequent among those who had new-onset of a metabolic factor vs those who did not (hypertension: 7.7 vs 6.0%; diabetes: 8.4 vs 6.6%; obesity: 7.4 vs 6.8%). Adjusted Cox models identified that increased risk of kidney stones was associated with new-onset hypertension (adjusted hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.25-2.27), new-onset diabetes (HR 1.78, 95% CI 1.07-2.96), and new-onset obesity (HR 1.78, 95% CI 1.15-2.74).

CONCLUSIONS

New-onset of hypertension, diabetes and obesity were all strongly associated with an increased risk of kidney stones in this prospective cohort study. Results suggest that a substantial proportion of kidney stones are potentially preventable by appropriate control of these metabolic risk factors.

Association of Urinary Oxalate Excretion With the Risk of Chronic Kidney Disease Progression

IMPORTANCE

Oxalate is a potentially toxic terminal metabolite that is eliminated primarily by the kidneys. Oxalate nephropathy is a well-known complication of rare genetic disorders and enteric hyperoxaluria, but oxalate has not been investigated as a potential contributor to more common forms of chronic kidney disease (CKD).

OBJECTIVE

To assess whether urinary oxalate excretion is a risk factor for more rapid progression of CKD toward kidney failure.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study assessed 3123 participants with stages 2 to 4 CKD who enrolled in the Chronic Renal Insufficiency Cohort study from June 1, 2003, to September 30, 2008. Data analysis was performed from October 24, 2017, to June 17, 2018.

EXPOSURES

Twenty-four-hour urinary oxalate excretion.

MAIN OUTCOMES AND MEASURES

A 50% decline in estimated glomerular filtration rate (eGFR) and end-stage renal disease (ESRD).

RESULTS

This study included 3123 participants (mean [SD] age, 59.1 [10.6] years; 1414 [45.3%] female; 1423 [45.6%] white). Mean (SD) eGFR at the time of 24-hour urine collection was 42.9 (16.8) mL/min/1.73 m2. Median urinary excretion of oxalate was 18.6 mg/24 hours (interquartile range [IQR], 12.9-25.7 mg/24 hours) and was correlated inversely with eGFR (r = -0.13, P < .001) and positively with 24-hour proteinuria (r = 0.22, P < .001). During 22 318 person-years of follow-up, 752 individuals reached ESRD, and 940 individuals reached the composite end point of ESRD or 50% decline in eGFR (CKD progression). Higher oxalate excretion was independently associated with greater risks of both CKD progression and ESRD: compared with quintile 1 (oxalate excretion, <11.5 mg/24 hours) those in quintile 5 (oxalate excretion, ≥27.8 mg/24 hours) had a 33% higher risk of CKD progression (hazard ratio [HR], 1.33; 95% CI, 1.04-1.70) and a 45% higher risk of ESRD (HR, 1.45; 95% CI, 1.09-1.93). The association between oxalate excretion and CKD progression and ESRD was nonlinear and exhibited a threshold effect at quintiles 3 to 5 vs quintiles 1 and 2. Higher vs lower oxalate excretion (at the 40th percentile) was associated with a 32% higher risk of CKD progression (HR, 1.32; 95% CI, 1.13-1.53) and 37% higher risk of ESRD (HR, 1.37; 95% CI, 1.15-1.63). Results were similar when treating death as a competing event.

CONCLUSIONS AND RELEVANCE

Higher 24-hour urinary oxalate excretion may be a risk factor for CKD progression and ESRD in individuals with CKD stages 2 to 4.

A preliminary survey of practice patterns across several European kidney stone centers and a call for action in developing shared practice

Currently an evidence-based approach to nephrolithiasis is hampered by a lack of randomized controlled trials. Thus, there is a need for common platforms for data sharing and recruitment of patients to interventional studies. A first step in achieving this objective would be to share practice methods and protocols for subsequent standardization in what is still a heterogeneous clinical field. Here, we present the results of a pilot survey performed across 24 European clinical kidney stone centers. The survey was distributed by a voluntary online questionnaire circulated between June 2017 and January 2018. About 46% of centers reported seeing on average 20 or more patients per month. Only 21% adopted any formal referral criteria. Centers were relatively heterogeneous in respect of the definition of an incident stone event. The majority (71%) adopted a formal follow-up scheme; of these, 65% included a follow-up visit at 3 and 12 months, and 41% more than 12 months. In 79% of centers some kind of imaging was performed systematically. 75% of all centers performed laboratory analyses on blood samples at baseline and during follow-up. All centers performed laboratory analyses on 24-h urine samples, the majority (96%) at baseline and during follow-up. There was good correspondence across centers for analyses performed on 24-h urine samples, although the methods of 24-h urine collection and analysis were relatively heterogeneous. Our survey among 24 European stone centers highlights areas of homogeneity and heterogeneity that will be investigated further. Our aim is the creation of a European network of stone centers sharing practice patterns and hosting a common database for research and guidance in clinical care.