Urolithiasis in Kidney Transplant Patients: A Multicenter KSER Research Series.

Background and Objectives: Urolithiasis occurrence is uncommon in kidney transplantation patients, though it has serious implications, including acute kidney injury in the transplanted kidney. This study investigates the leading causes of urolithiasis in kidney transplantation patients, the diagnostic process, and the outcomes of multimodal management. Materials and Methods: Data collection spanned from January 1997 to December 2021, involving kidney transplantation patients with urolithiasis from the database of the Korean Society of Endourology and Robotics (KSER) research committee. Analysis encompassed factors triggering urolithiasis, the diagnostic process, stone attributes, treatment methods, and outcomes. Results: Our analysis included 58 kidney transplantation patients with urolithiasis from eight medical centers. Of these patients, 37 were male and 4 had previous urolithiasis diagnoses. The mean age was 59.09 ± 10.70 years, with a mean duration from kidney transplantation to diagnosis of 76.26 ± 183.14 months. The most frequent method of stone detection was through asymptomatic routine check-ups (54.7%). Among the 58 patients, 51 underwent stone treatment. Notably, 95.3% of patients with ureter stones received treatment, a significantly higher rate than the 66.7% of patients with renal stones (p = 0.010). Success rates showed no significant differences between renal (70%) and ureter stone (78.0%) groups (p = 0.881). Conclusions: Urolithiasis in transplanted kidneys constitutes an acute condition requiring emergency intervention. Endo-urological interventions are effective for kidney transplantation patients with urolithiasis. To ensure prevention and early detection, diligent follow-up and routine imaging tests are necessary.

Risk Factors for Increased Stent-associated Symptoms Following Ureteroscopy for Urinary Stones: Results From STENTS.

PURPOSE: The STudy to Enhance uNderstanding of sTent-associated Symptoms sought to identify risk factors for pain and urinary symptoms, as well as how these symptoms interfere with daily activities after ureteroscopy for stone treatment. MATERIALS AND METHODS: This prospective observational cohort study enrolled patients aged ≥12 years undergoing ureteroscopy with ureteral stent for stone treatment at 4 clinical centers. Participants reported symptoms at baseline; on postoperative days 1, 3, 5; at stent removal; and day 30 post-stent removal. Outcomes of pain intensity, pain interference, urinary symptoms, and bother were captured with multiple instruments. Multivariable analyses using mixed-effects linear regression models were identified characteristics associated with increased stent-associated symptoms. RESULTS: A total of 424 participants were enrolled. Mean age was 49 years (SD 17); 47% were female. Participants experienced a marked increase in stent-associated symptoms on postoperative day 1. While pain intensity decreased ∼50% from postoperative day 1 to postoperative day 5, interference due to pain remained persistently elevated. In multivariable analysis, older age was associated with lower pain intensity (P = .004). Having chronic pain conditions (P < .001), prior severe stent pain (P = .021), and depressive symptoms at baseline (P < .001) were each associated with higher pain intensity. Neither sex, stone location, ureteral access sheath use, nor stent characteristics were drivers of stent-associated symptoms. CONCLUSIONS: In this multicenter cohort, interference persisted even as pain intensity decreased. Patient factors (eg, age, depression) rather than surgical factors were associated with symptom intensity. These findings provide a foundation for patient-centered care and highlight potential targets for efforts to mitigate the burden of stent-associated symptoms.

Fluid intake recommendations in urolithiasis and general advice to patients without metabolic risk factors.

Urolithiasis is a highly prevalent global disease with substantially increasing incidence in the last two decades. Data from the literature suggests that 26%-50% of patients will have a recurrence within 10 years after an initial symptomatic stone episode. Therefore, interest has been raised in preventive strategies, aiming to modify the risk factors of stone recurrence by implementing dietary and lifestyle changes and specific medical treatments for stone formers, depending on their recurrence risk factors. Certain dietary factors are thought to contribute significantly to the increased incidence of urolithiasis, particularly a diet low in fiber and high in animal protein, fat, and sodium. Fluid intake is perhaps the most important and modifiable step in the prevention of urolithiasis, irrespective of stone composition. However, the amount of fluid to be consumed and the implications of various fluid types on stone formation are still controversial. In this article, the relationship between fluid intake, beverage types and stone formation-prevention will be discussed. Moreover, general dietary recommendations for patients without metabolic risk factors will be reviewed based on the current literature.

Dietary weight loss strategies for kidney stone patients.

PURPOSE: Overweight has been associated with an increased risk of incident and recurrent kidney stone disease. Weight reduction is the therapeutic consequence to decrease the risk of stone formation. This review examines the effectiveness of different weight loss strategies on weight reduction and cardiometabolic risk profile, with a particular focus on risk factors for urolithiasis. METHODS: A selective literature search was performed using PubMed and Cochrane library. RESULTS: Clinical evidence for the potential benefits of dietary weight loss strategies for kidney stone disease is limited. A conventional, energy-restricted diet may significantly induce weight loss and reduce urinary supersaturation of calcium oxalate in overweight individuals with or without a history of stone formation. The current data indicate that an energy-restricted diet with partial meal replacement may additionally decrease the relative supersaturation of uric acid and further improve the cardiometabolic risk profile, and, thus, may be a favourable option for overweight kidney stone patients. Studies on the Mediterranean and DASH diets on the association between weight loss and the risk of urinary stone formation are lacking. CONCLUSION: An energy-restricted diet with or without meal replacement could be a promising weight loss strategy for overweight kidney stone patients. Further studies are needed to evaluate the impact of different weight loss strategies on urinary risk factors and cardiometabolic risk profile in urolithiasis.

Urinary stone disease in Syrian children.

BACKGROUND: Pediatric urinary stone disease (USD) is a costly medical problem. This study aims to assess the clinical characteristics and outcomes of common and rare causes of pediatric USD. METHODS: A retrospective descriptive cohort study included all children < 13 years of age with confirmed USD admitted to the Children's University Hospital in Damascus, Syria, from January 2013 to December 2019. The study sample was divided into two groups based on etiologies: common and rare causes groups. RESULTS: We evaluated 235 patients; 147 of them were males, and the male-to-female ratio was 1.7:1. The common causes group consisted of 203 patients (mean age 3.52 ± 3.66 years) and mainly included metabolic disorders (45.5%) and anatomical abnormalities (22.3%), while the rare causes group included 32 cases (mean age 4.93 ± 4.08 years), 12 patients with uric acid stones (37.5%), 7 patients with cystinuria (21.9%), and primary hyperoxaluria in 5 patients (15.6%). In addition, 39.6% of study patients were born to consanguineous marriages. Sixty-two patients developed AKI, and eleven patients had chronic kidney disease (CKD). Patients with rare causes were more likely to have AKI, CKD, bilateral stones, and recurrent stones (P-value < 0.05). Stone analysis was performed on 83 patients, and the main stone types were calcium oxalate (34.9%), uric acid (14.4%), and struvite stones (12%). Surgery was the most performed treatment in 101 patients (56.7%). CONCLUSION: Patients with rare causes of pediatric USD are at a higher risk for severe complications and require early diagnosis and management. The high rate of uric acid stones in our society requires further evaluation for possible underlying causes. A higher resolution version of the Graphical abstract is available as Supplementary information.

Outcomes Associated with the Endourological Management of Stent Encrustation: Findings from a Literature Review on Behalf of the EAU YAU Urolithiasis Group.

PURPOSE OF REVIEW: Double J ureteric stents (DJs) are useful aids for urinary drainage in case of stones or tumour causing ureteric obstruction. Prolonged dwelling time such as when forgotten can lead to encrustation. Our aim was to perform a literature review to evaluate outcomes associated with endourological management of encrusted stents (ES). RECENT FINDINGS: There now exist validated tools which can aid in grading the severity of encrustation and aid operative planning such as the total number of surgeries that may be required. Evaluation of different treatment strategies remains under reported. Removal of encrusted stent is a challenging problem, and it typically requires a multimodal endourological approach.

Safety and efficacy of ureteroscopy for urolithiasis in octogenarians.

OBJECTIVE: To examine the safety and efficacy of ureteroscopy (URS) for urolithiasis in octogenarians, and identify preoperative risk factors for the incidence of postoperative complications. METHODS: The patients who underwent URS for urolithiasis were divided into octogenarians and younger patients (age: <80 years), and the groups were compared regarding their clinical characteristics, intraoperative and postoperative complications, and stone-free rate. The predictors of postoperative complications were evaluated using logistic regression models. RESULTS: A total of 1207 patients were included, 166 in the octogenarian patient group and 1041 in the younger patient group. The proportion of female patients (p < 0.001), American Society of Anesthesiologists (ASA) score (p < 0.001), rate of preoperative pyelonephritis (p < 0.001), and diabetes mellitus (p = 0.003) were higher in the octogenarian group. No statistically significant differences were found between the two groups regarding stone size, location, and intraoperative complications. Postoperative complications, which reached a significant difference, were observed in 34 (20.5%) octogenarians and 117 (11.2%) younger patients (p = 0.002). However, age itself was not significantly associated with postoperative fever, the most frequent postoperative complication, in multivariate analysis. Female sex, ASA score of ≥3, history of diabetes mellitus, and prolonged operative time (≥120 min) were the significant predictors of fever. The stone-free rate in the octogenarian group was superior to that in the younger patient group (80.1% vs. 70.6%, respectively; p = 0.035). CONCLUSION: Our results suggest that URS for urolithiasis can be safely and effectively applied to octogenarians in selected cases.

Impact of body mass index on size and composition of urinary stones: a systematic review and meta-analysis.

BACKGROUND: Several studies have explored the impact of BMI on size and composition of urinary stones. Because there were controversies, a meta-analysis was necessary to be carried out to provide some evidence of the relationship of BMI and urolithiasis. MATERIALS AND METHODS: PubMed, Medline, Embase, Web of Science databases, and the Cochrane Library were searched up to August 12th 2022 for eligible studies. The urolithiasis patients were summarized into two groups: BMI < 25 and ≥ 25 kg/m2. Summary weighted mean difference (WMD), relative risk (RR) and 95% confidence intervals (CI) were calculated through random effects models in RevMan 5.4 software. RESULTS: A total of fifteen studies involving 13,233 patients were enrolled in this meta-analysis. There was no significant correlation of BMI and size of urinary stone (WMD -0.13mm, 95% CI [-0.98, 0.73], p = 0.77). Overweight and obesity increased the risk of uric acid stones in both genders and in different regions (RR=0.87, [95% CI] = 0.83, 0.91, p<0.00001). There was a higher risk of calcium oxalate stones formation in overweight and obesity group in total patients (RR=0.95, [95% CI] = 0.91, 0.98, p = 0.006). The relationship of BMI and calcium phosphate was not observed in this meta-analysis (RR=1.12, [95% CI] = 0.98, 1.26, p = 0.09). Sensitivity analysis was performed and indicated similar results. CONCLUSIONS: The current evidence suggests a positive association between BMI and uric acid and calcium oxalate stones. It would be of great guiding significance to consider losing weight when treating and preventing urinary stones.

Urolithiasis: History, epidemiology, aetiologic factors and management.

Urolithiasis is defined as a disease diagnosed by the presence of one or more stones in the urinary tract. It is one of the oldest and most widespread diseases known to man, their discovery and characterisation chronology began with the civilisation's history. This pathology has a multifactorial aetiology, very frequent worldwide with geographic and racial variation, their prevalence is increasing in lockstep with socioeconomic development. In fact, this disorder affects between 2 and 20% of the population, with an approximate recurrence rate of 30% to 50% in 5 years. Furthermore, calciumtype stones, which are composed of calcium oxalate (CaOx) alone or a mixture of CaOx and calcium phosphate are the most common, accounting for more than 80% of cases. The medical management of urolithiasis is done by medical treatments and/or by surgical intervention for the stones extraction by the techniques such as extracorporeal shock wave lithotripsy (ESWL), ureteroscopy (URS), percutaneous nephrolithotomy (PCNL) and open surgery. However, various therapies, including thiazide diuretics and alkaline citrate, are used in an attempt to prevent stones recurrence induced by hypercalciuria and hyperoxaluria, but the scientific evidence for their effectiveness is less convincing. On the other hand, endoscopic and ESWL methods have revolutionised the treatment of urinary lithiasis, but these costly methods, can cause acute kidney injury and decreased renal function, in addition, do not prevent the probability of new stone formation. The deepening of our knowledge on all points relating to this disease is a priority for specialists in order to find adequate solutions for this disease. This review provides an overview of urolithiasis, its history, epidemiology, clinical manifestation, diagnosis and treatment methods.

2022 Recommendations of the AFU Lithiasis Committee: Medical management - from diagnosis to treatment.

The morphological-compositional analysis of urinary stones allows distinguishing schematically several situations: dietary, digestive, metabolic/hormonal, infectious and genetic problems. Blood and urine testing are recommended in the first instance to identify risk factors of urinary stone disease in order to avoid recurrence or progression. The other objective is to detect a potential underlying pathology associated with high risk of urinary stone disease (e.g. primary hyperparathyroidism, primary or enteric hyperoxaluria, cystinuria, distal renal tubular acidosis) that may require specific management. Lifestyle-diet measures are the basis of the management of all stone types, but pharmacological treatments may be required. METHODOLOGY: These recommendations were developed using two methods: the Clinical Practice Recommendation (CPR) method and the ADAPTE method, depending on whether the question was considered in the European Association of Urology (EAU) recommendations (https://uroweb.org/guidelines/urolithiasis) [EAU 2022] and their adaptability to the French context.

DIFFERENT APPROACHES TO MANAGING UROLITHIASIS IN KIDNEY TRANSPLANT PATIENTS - A CASE REPORT.

Urolithiasis is a rare urologic complication after kidney transplantation, and its diagnosis and treatment can be challenging for clinicians. In our 52-year-old male patient, graft hydronephrosis was found six months after transplantation. The patient had recurrent urinary tract infections followed by macrohematuria and an increase in creatinine levels. Computerized tomography revealed a 13-mm diameter stone in the ureter of the transplanted kidney as the cause of obstruction. Percutaneous nephrostomy was placed in the graft to solve the obstruction. Initial endoscopic treatment with a retrograde approach failed. An antegrade approach through a previously placed nephrostomy was not successful either. By a repeated retrograde approach, laser lithotripsy was performed successfully. The patient has been monitored for six months and has stable graft function without hydronephrosis or stones. As in our patient's case, the diagnosis and treatment of urolithiasis in kidney transplant patients is challenging, and minimally invasive procedures are the treatment of choice.

Modified Atkins diet for drug-resistant epilepsy and the risk of urolithiasis.

BACKGROUND: Ketogenic diet (KD) is widely used for drug-resistant epilepsy (DRE). The study was designed to evaluate one of the risk factors for development of renal calculi with KD. METHODS: Twenty patients with DRE on Modified Atkins diet (MAD) were subjected to full history and laboratory investigations, including microscopic urine analysis, urinary calcium after overnight fasting, and calcium/creatinine ratio, as well as pelviabdominal ultrasound. Frequency and severity of seizures assessed by Chalfont severity score were recorded. All assessment measures were repeated after 3 and 6 months of KD therapy. RESULTS: There were significant reductions in both frequency and severity of seizures, yet 2 patients (10%) developed renal stones after 6 months on KD. Gross hematuria was reported in 1 of those 2 patients (50%), but microscopic hematuria was detected in both patients. The urine calcium and the urine calcium/creatinine ratio were elevated in both patients having renal calculi after 6 months. CONCLUSIONS: KD increases the risk of renal stones with hypercalciuria among the causes. We recommend initiation of prophylactic measures once KD is commenced by maximizing fluid intake and urine alkalinization with regular urinary studies including calcium/creatinine ratio and renal ultrasound for patients with symptoms. IMPACT: KD has been increasingly used in epilepsy management and beyond. The potential side effects of such diet should be highlighted while valuing the merits. KD increases the risk of renal stones because of hypercalciuria among other causes. We recommend initiation of prophylactic measures once KD is commenced by maximizing fluid intake and urine alkalinization with estimation of urinary calcium/creatinine ratio and renal ultrasound in patients with relevant symptoms.

Outcomes and costs of ureteroscopy, extracorporeal shockwave lithotripsy, and percutaneous nephrolithotomy for the treatment of urolithiasis: an analysis based on health insurance claims data in Germany.

PURPOSE: Comparisons of ureteroscopy (URS), extracorporeal shockwave lithotripsy (SWL), and percutaneous nephrolithotomy (PCNL) for urolithiasis considering long-term health and economic outcomes based on claims data are rare. Our aim was to analyze URS, SWL, and PCNL regarding complications within 30 days, re-intervention, healthcare costs, and sick leave days within 12 months, and to investigate inpatient and outpatient SWL treatment as the latter was introduced in Germany in 2011. METHODS: This retrospective cohort study based on German health insurance claims data included 164,203 urolithiasis cases in 2008-2016. We investigated the number of complications within 30 days, as well as time to re-intervention, number of sick leave days and hospital and ambulatory health care costs within a 12-month follow-up period. We applied negative binomial, Cox proportional hazard, gamma and two-part models and adjusted for patient variables. RESULTS: Compared to URS cases, SWL and PCNL had fewer 30-day complications, time to re-intervention within 12 months was decreased for SWL and PCNL, SWL and PCNL were correlated with a higher number of sick leave days, and SWL and particularly PCNL were associated with higher costs. SWL outpatients had fewer complications, re-interventions and lower costs than inpatients. This study was limited by the available information in claims data. CONCLUSION: URS cases showed benefits in terms of fewer re-interventions, fewer sick leave days, and lower healthcare costs. Only regarding complications, SWL was superior. This emphasizes URS as the most frequent treatment choice. Furthermore, SWL outpatients showed less costs, fewer complications, and re-interventions than inpatients.

Do dietary factors play a role in infantile urolithiasis?

BACKGROUND: Urolithiasis is a significant cause of morbidity that may be diagnosed at a young age. However, there is little research on the role of nutrition in pediatric urolithiasis, and research on the infantile period is extremely rare. The aim of this study is to investigate the effect of dietary factors on those diagnosed with "idiopathic" infantile urolithiasis. METHOD: The study group included 44 infants without a proven etiological factor for urolithiasis. The control group consisted of 60 fully healthy infants of matched age and gender. The parents and caregivers of each infant in the patient and control groups were carefully questioned by the same researcher for their dietary characteristics. RESULT: The duration of formula usage and daily volume of formula were statistically higher in the study group than the control group (p = 0.041 and p = 0.003, respectively). The urolithiasis group consumed significantly more cow's milk and dairy products (p = 0.033 and p = 0.001). There was no statistically meaningful difference between the two groups in terms of starting age for free water and salty food, as well as daily water intake. CONCLUSION: We concluded that dietary conditions could also be a risk factor for idiopathic urolithiasis. We believe that nutritional factors for infantile urolithiasis should be better described, in addition to genetic, anatomical, and metabolic factors. A higher resolution version of the Graphical abstract is available as Supplementary information.

Endothelial Dysfunction: An Intermediate Clinical Feature between Urolithiasis and Cardiovascular Diseases.

An epidemiological relationship between urolithiasis and cardiovascular diseases has extensively been reported. Endothelial dysfunction is an early pathogenic event in cardiovascular diseases and has been associated with oxidative stress and low chronic inflammation in hypertension, coronary heart disease, stroke or the vascular complications of diabetes and obesity. The aim of this study is to summarize the current knowledge about the pathogenic mechanisms of urolithiasis in relation to the development of endothelial dysfunction and cardiovascular morbidities. METHODS: A non-systematic review has been performed mixing the terms "urolithiasis", "kidney stone" or "nephrolithiasis" with "cardiovascular disease", "myocardial infarction", "stroke", or "endothelial dysfunction". RESULTS: Patients with nephrolithiasis develop a higher incidence of cardiovascular disease with a relative risk estimated between 1.20 and 1.24 and also develop a higher vascular disease risk scores. Analyses of subgroups have rendered inconclusive results regarding gender or age. Endothelial dysfunction has also been strongly associated with urolithiasis in clinical studies, although no systemic serum markers of endothelial dysfunction, inflammation or oxidative stress could be clearly related. Analysis of urine composition of lithiasic patients also detected a higher expression of proteins related to cardiovascular disease. Experimental models of hyperoxaluria have also found elevation of serum endothelial dysfunction markers. CONCLUSIONS: Endothelial dysfunction has been strongly associated with urolithiasis and based on the experimental evidence, should be considered as an intermediate and changeable feature between urolithiasis and cardiovascular diseases. Oxidative stress, a key pathogenic factor in the development of endothelial dysfunction has been also pointed out as an important factor of lithogenesis. Special attention must be paid to cardiovascular morbidities associated with urolithiasis in order to take advantage of pleiotropic effects of statins, angiotensin receptor blockers and allopurinol.

Analysis of potential risk factors associated with urolithiasis.

OBJECTIVES: Eating habits, regular fluid intake, lifestyle and body composition are a primary point of research. The research focused on urolithiasis approaching potential danger, trying to interpret risk factors responsible for urolithiasis and disease recurrence. METHODS: Research file contains 166 patients suffering from urolithiasis, 87 (52.4%) males and 79 (47.6%) females, and 172 healthy subjects from control group. All data was accessed using fully anonymous and confidential questionnaires, then evaluated in the statistical GNU PSPP 1.4 software. RESULTS: More than 3/4 patients have a BMI higher than 24.9 and almost 40% of subjects have obesity class I, II, or III. Patients have higher BMI than subjects (d = 1.285; p < 0.001), and females have significantly higher BMI than males (d = 0.385; p = 0.007). Female patients have higher BMI than Slovak healthy females (p < 0.001; MD = 4.581; CI: 3.24-5.93). Patients have a lower daily water intake than subjects (φc = 0.157; p = 0.04) and more than 2/3 of patients have insufficient water intake. Sedentary employment prevails markedly in patients than in subjects. Patients are much less physically active than subjects (φc = 0.633; p < 0.001) and the difference is rising with increasing age of patients (ρ = - 0.232; p = 0.003). Low physical and working activity are characteristic for patients in this study. Patients smoke more often in comparison to subjects (φc = 0.261; p < 0.001). Patients consume more meats (red and white), cocoa and lentils. A lot of patients exceed recommended daily intake of pork and beef. CONCLUSIONS: Many conditions are different for the healthy population and patients' group. High BMI, low fluid intake, exceeded red meat consumption, and low physical activity are the strongest factors for developing urolithiasis. Patients should consume more fluids daily, exercise frequently and vigorously, and lower amount of red meat consumed.

Incidence and risk factors for urolithiasis recurrence after endourological management of kidney stones: A retrospective single-centre study.

INTRODUCTION: Almost half of the patients have had recurrent nephrolithiasis despite undergoing effective treatment. Our objective is to determine the recurrence rate of lithiasis after endourological management of nephrolithiasis and identify the risk factors for these recurrences. METHODS: Data were gathered retrospectively from all patients who were treated for nephrolithiasis by endourological management from May 2014 to January 2017 in our university hospital. The patients were devised into two groups: with and without recurrence. Many variables were also compared between these two groups. RESULTS: During this period 265 patients were treated for upper urinary tract stone. A total of 190 patients were included in the study. The median age and median BMI of the patients were 57.5 years and 25.2kg/m2, respectively. A biochemical analysis of the stones was performed in 117 (61.5%) patients. The most common types of stones were calcium oxalate monohydrate stones (n=44, 23.2%), mixed stones (n=39, 20.5%) including mixed calcium oxalate (n=10; 8.5%), calcium oxalate dihydrate stones (n=13, 6.8%) and uric acid stones (n=11, 5.8%). At the end of a median follow-up of 32 months (range, 13-61 monthes), 49 patients (25.8%) had a recurrent stone. In univariate analysis, the risk factors for recurrence were BMI greater than 25kg/m2 (HR: 2; P<0.05), diabetes (HR: 3.73; P<0.008) and smoking (HR: 3.1; P<0.039). However age (HR: 0.96: P<0.003) and high blood pressure (HR: 0.37; P<0.027) were protective factors. In multivariate analysis, diabetes, smoking, hypertension, and age are still risk factors for recurrence. CONCLUSION: Stone recurrence is common after the management of urinary stones. In this study 25.8% of patients had recurred stone disease after endourological management with a median follow-up of 32 months. Our study findings showed that diabetes and smoking are risk factors for recurrence, while age and blood hypertension are protective factors that decreased the risk of recurrence.

[Current state of metaphylaxis of urinary stones in Russian Federation].

INTRODUCTION: Urolithiasis is one of the most common urological diseases in adults. Increased life expectancy of the population in developed countries, make urolithiasis topical issue and requires close attention. Due to the high risk of recurrent stone formation causing repeated surgical interventions, the issue of effective urinary stone metaphylaxis is very important today. MATERIALS AND METHODS: To study the current state of the problem of urolithiasis metaphylaxis among Russian urologists, an anonymous questionnaire was applied. A 25-question questionnaire was sent to e-mail to more than 4,000 Russian urologists. A total of 1,238 specialists completed the questionnaire. The database compiled from the received responses was processed and presented with descriptive statistics in the form of tables and charts. RESULTS: According to the survey, more than half of the 831 (67.1%) specialists specialized in the treatment of urolithiasis. It was noted that 626 (86%) inpatient urologists and 205 (40%) outpatient urologists specialized in the treatment of urolithiasis. Only 521 (69.6%) urologists specializing in surgical treatment of urolithiasis give a patient a stone fragment to analyze its chemical composition. At the same time, half of the respondents reported that less than 10% of patients come to them for further metaphylaxis. One of the main reasons for not analyzing the chemical composition of the stone was the fact that 877 (70,84%) specialists indicated the inaccessibility of analysis under the state guarantee program, 503 (40,63%) specialists indicated the patients satisfaction with the results of minimally invasive surgical treatment and lack of sufficient motivation for further examinations. At the same time, less than 3% of specialists can perform stone analysis within the framework of the state guaranty program. 1180 (96,8%) respondents practiced the prophylaxis of recurrent calculi formation, but only 336 (28,47%) performed comprehensive metabolic examination of all patients followed by prescription of drug therapy and appropriate diet. CONCLUSIONS: Our survey revealed low involvement of urologists at the outpatient level in the process of conservative treatment and metaphylaxis of urolithiasis, low activity of urologists in performing complex metabolic study and comprehensive prevention of recurrent stone formation, low percentage of performing chemical composition analysis of stone and low activity of urologists in performing primary litholytic therapy of urate stones. Based on this analysis of the responses of most Russian urologists, it is possible to formulate recommendations to remove the obstacles to providing patients with urolithiasis with quality medical care in terms of conservative therapy and metaphylaxis of urolithiasis.

[Functional state of kidneys and cardiovascular risk in patients with urolithiasis in an outpatient setting].

AIM: To analyze the functional state of the kidneys and vascular stiffness in patients with urinary stone disease in an outpatient setting. MATERIAL AND METHODS: A total of 110 patients with urinary stone disease aged 17-72 years were included in the study. The stone size was 2,67 (1,90-3,49) mm. A clinical examination included evaluation of vascular stiffness, serum level of creatinine, cystatin C, calcium, phosphorus, sodium, magnesium, uric acid and total cholesterol. The glomerular filtration rate (eGFR) was calculated based on the formulas CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) and MDRD (Modification of Diet in Renal Disease) and Hoek's equations using creatinine and cystatin C, respectively. RESULTS: Most often, urinary stone disease was associated with arterial hypertension (75%), a sedentary lifestyle (66.3%), hypercholesterolemia (53.6%), obesity (47.2%), hyperuricemia (44.5%) and smoking (40.9%). The median and interquartile range of eGFR according to CKD-EPI, MDRD and Hoek's equations was 100.00 (78.00;113.00) ml/min, 96.00 (71.00;106.00) ml/min and 77.65 (61.50; 93.60) ml/min, respectively. The normal GFR was significantly more often detected by the formula CKD-EPI (66.3%) in comparison with the Hoek's equations (52.7%), p<0.05. A decrease in mild GFR was found in 21 (19.0%) patients according to CKD-EPI and 33 (30.0%) according to Hoek's equations (p<0.05). In the subgroup of patients with a mild to moderate decrease in GFR according to the Hoek's equations, stiffness index and resistive index were significantly higher than in the similar subgroup of patients with decrease of GFR measured using the CKD-EPI formula (p<0.05). A negative correlation between GFR calculated using three formulas and Augmentation Index was established. CONCLUSIONS: In patients with urinary stone disease, potential cardiovascular risk factors are very common. The study of serum cystatin C level with calculation of GFR according to Hoek's equations in individuals with urolithiasis allows to evaluate total renal nitrogen excretion, as well as the level of the cardiovascular risk in the early stages of the disease.

Cellular and Molecular Mechanisms of Kidney Injury in 2,8-Dihydroxyadenine Nephropathy.

BACKGROUND: Hereditary deficiency of adenine phosphoribosyltransferase causes 2,8-dihydroxyadenine (2,8-DHA) nephropathy, a rare condition characterized by formation of 2,8-DHA crystals within renal tubules. Clinical relevance of rodent models of 2,8-DHA crystal nephropathy induced by excessive adenine intake is unknown. METHODS: Using animal models and patient kidney biopsies, we assessed the pathogenic sequelae of 2,8-DHA crystal-induced kidney damage. We also used knockout mice to investigate the role of TNF receptors 1 and 2 (TNFR1 and TNFR2), CD44, or alpha2-HS glycoprotein (AHSG), all of which are involved in the pathogenesis of other types of crystal-induced nephropathies. RESULTS: Adenine-enriched diet in mice induced 2,8-DHA nephropathy, leading to progressive kidney disease, characterized by crystal deposits, tubular injury, inflammation, and fibrosis. Kidney injury depended on crystal size. The smallest crystals were endocytosed by tubular epithelial cells. Crystals of variable size were excreted in urine. Large crystals obstructed whole tubules. Medium-sized crystals induced a particular reparative process that we term extratubulation. In this process, tubular cells, in coordination with macrophages, overgrew and translocated crystals into the interstitium, restoring the tubular luminal patency; this was followed by degradation of interstitial crystals by granulomatous inflammation. Patients with adenine phosphoribosyltransferase deficiency showed similar histopathological findings regarding crystal morphology, crystal clearance, and renal injury. In mice, deletion of Tnfr1 significantly reduced tubular CD44 and annexin two expression, as well as inflammation, thereby ameliorating the disease course. In contrast, genetic deletion of Tnfr2, Cd44, or Ahsg had no effect on the manifestations of 2,8-DHA nephropathy. CONCLUSIONS: Rodent models of the cellular and molecular mechanisms of 2,8-DHA nephropathy and crystal clearance have clinical relevance and offer insight into potential future targets for therapeutic interventions.