Metabolic Syndrome and Kidney Stone Disease: A Systematic Review of Literature

The Multidisciplinary Approach in the Management of Patients with Kidney Stone Disease-A State-of-the-Art Review

Kidney stone disease has a multifactorial etiology, and evolving dietary habits necessitate continuous updates on the impact of dietary components on lithogenesis. The relationship between diseases influenced by lifestyle, such as obesity and diabetes, and kidney stone risk underscores the need for comprehensive lifestyle analysis. Effective management of kidney stones requires a multidisciplinary approach, involving collaboration among nutritionists, urologists, nephrologists, and other healthcare professionals to address the complex interactions between diet, lifestyle, and individual susceptibility. Personalized dietary therapy, based on each patient's unique biochemical and dietary profile, is essential and necessitates comprehensive nutritional assessments. Accurate dietary intake evaluation is best achieved through seven-day, real-time dietary records. Key factors influencing urinary risk include fluid intake, dietary protein, carbohydrates, oxalate, calcium, and sodium chloride. Personalized interventions, such as customized dietary changes based on gut microbiota, may improve stone prevention and recurrence. Current research suggests individualized guidance on alcohol intake and indicates that tea and coffee consumption might protect against urolithiasis. There is potential evidence linking tobacco use and secondhand smoke to increased kidney stone risk. The effects of vitamins and physical activity on kidney stone risk remain unresolved due to mixed evidence. For diseases influenced by lifestyle, conclusive evidence on targeted interventions for nephrolithiasis prevention is lacking, though preliminary research suggests potential benefits. Management strategies emphasize lifestyle modifications to reduce recurrence risks, support rapid recovery, and identify predisposing conditions, highlighting the importance of these changes despite inconclusive data.

Is Totally Tubeless Percutaneous Nephrolithotomy a Safe and Efficacious Option for Complex Stone Disease?

Background: Percutaneous nephrolithotomy is the gold standard treatment for large, complex intrarenal stones. Historically, this was performed using a nephrostomy tube (PCN) and/or internalized ureteral stent at the end of the procedure. However, totally tubeless nephrolithotomy (tt-PCNL) is a novel technique where no tubes (no stent nor nephrostomy tube) are left post-operatively. We review the literature on this subject regarding peri-operative outcomes, post-operative outcomes, and potential complications of the procedure, discuss our technique, and make recommendations on implementation for centers not currently utilizing the procedure. Materials and methods: We performed a comprehensive search of the literature on totally tubeless nephrolithotomy using MEDLINE database search. Our search included prior review articles, meta-analyses, systematic reviews, primary research articles, case reports, and case studies. Results: In comparison to prior approaches where a stent or nephrostomy tube is placed, tt-PCNL has a similar complication rate and better post-operative outcomes. Totally tubeless PCNL has similar operative times and similar changes in hemoglobin. However, it had shorter length of stays across all studies. The mean difference in length of stay in the studies reviewed was 1.96 days. Additionally, tt-PCNL had decreased post-operative analgesic requirements and pain scores. Conclusions: This review highlights totally tubeless percutaneous nephrolithotomy as a safe and feasible surgical technique with improved outcomes in properly selected patients.

A cross-sectional analysis of the relationship between the non-high density to high density lipoprotein cholesterol ratio (NHHR) and kidney stone risk in American adults

BACKGROUND

Recent interest in the Non-High Density to High Density Lipoprotein Cholesterol ratio (NHHR) has emerged due to its potential role in metabolic disorders. However, the connection between NHHR and the development of kidney stones still lacks clarity. The primary goal of this research is to explore how NHHR correlates with kidney stone incidence.

METHODS

An analysis was conducted on the data collected by the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018, focusing on adults over 20 years diagnosed with kidney stones and those with available NHHR values. Employing weighted logistic regression and Restricted Cubic Spline (RCS) models, NHHR levels' correlation with kidney stone risk was examined. Extensive subgroup analyses were conducted for enhanced reliability of the findings.

RESULTS

The findings indicate a heightened kidney stone risk for those at the highest NHHR levels relative to those at the lowest (reference group). A notable non-linear correlation of NHHR with kidney stone incidence has been observed, with a significant P-value (< 0.001), consistent across various subgroups.

CONCLUSION

A clear link exists between high NHHR levels and increased kidney stone risk in the American adult population. This study highlights NHHR's significance as a potential indicator in kidney stone formation.

Basal metabolic rate and the risk of urolithiasis: a two-sample Mendelian randomization study

OBJECTIVE

Few studies have investigated the impact of basal metabolic rate (BMR) on the development of urolithiasis, and the causal relationship is yet to be established. In this study, a two-sample Mendelian randomization (MR) analysis was utilized to identify the causal relationship between BMR and risk of urolithiasis.

METHOD

Genetic instruments for BMR were drawn from a public genome-wide association study (GWAS). Summary dates on BMR and urolithiasis were obtained from a GWAS meta-analysis with sample sizes of 454,874 and 212,453, respectively. The inverse-variance weighted (IVW) method was provided as the main approach to estimate the causal relationship. The weighted-median method and the MR-Egger method were used as supplements to the IVW method. In addition, we conducted sensitivity analyses, including heterogeneity tests, pleiotropy tests and leave-one-out analysis, to assess the robustness of the outcomes. Furthermore, the funnel plot asymmetry was visually inspected to evaluate possible bias.

RESULTS

The inverse-variance weighted data revealed that genetically predicted BMR significantly decreased the risk of urolithiasis [beta coefficient (beta): - 0.2366, odds ratio (OR): 0.7893, 95% confidence interval (CI) 0.6504-0.9579, p = 0.0166].

CONCLUSIONS

BMR has causal effects on urolithiasis in an MR study, and the risk of urolithiasis in patients with lower levels of BMR is higher.

Metabolic syndrome and the urinary microbiome of patients undergoing percutaneous nephrolithotomy

Objective

To identify possible stone-promoting microbes, we compared the profiles of microbes grown from stones of patients with and without metabolic syndrome (MetS). The association between MetS and urinary stone disease is well established, but the exact pathophysiologic relationship remains unknown. Recent evidence suggests urinary tract dysbiosis may lead to increased nephrolithiasis risk.

Methods

At the time of percutaneous nephrolithotomy, bladder urine and stone fragments were collected from patients with and without MetS. Both sample types were subjected to expanded quantitative urine culture (EQUC) and 16 S ribosomal RNA gene sequencing.

Results

Fifty-seven patients included 12 controls (21.1%) and 45 MetS patients (78.9%). Both cohorts were similar with respect to demographics and non-MetS comorbidities. No controls had uric acid stone composition. By EQUC, bacteria were detected more frequently in MetS stones (42.2%) compared to controls (8.3%) (p=0.041). Bacteria also were more abundant in stones of MetS patients compared to controls. To validate our EQUC results, we performed 16 S ribosomal RNA gene sequencing. In 12/16 (75.0%) sequence-positive stones, EQUC reliably isolated at least one species of the sequenced genera. Bacteria were detected in both "infectious" and "non-infectious" stone compositions.

Conclusion

Bacteria are more common and more abundant in MetS stones than control stones. Our findings support a role for bacteria in urinary stone disease for patients with MetS regardless of stone composition.

The Prevalence of Nephrolithiasis and Associated Risk Factors Among the Population of the Riyadh Province, Saudi Arabia

Background and objective Kidney stones, also referred to as nephrolithiasis or renal calculi, is a condition where crystal depositions are formed within the kidney and ideally excreted from the body via the urethra with no pain; however, larger calculi may cause significant pain and require further medical assistance. The vast majority of patients who develop renal calculi form calcium stones, which are either a composition of calcium oxalate or calcium phosphate. Other types include uric acid, struvite, and cysteine. While kidney stones are one of the most significant diseases among the Saudi population, which require an acute emergency intervention to prevent serious long-term complications, there are limited studies published regarding this condition in Saudi communities. In light of this, we performed this study to assess the prevalence, incidence, and risk factors of kidney stones among the population of Riyadh, Saudi Arabia. Methods This was a cross-sectional study conducted in Riyadh, Saudi Arabia between August and October 2023, aiming to estimate the prevalence and risk factors of nephrolithiasis among residents of the Riyadh province. Data were collected through an electronic questionnaire in both Arabic and English and distributed via social media in addition to barcode handouts in various selected venues in Riyadh. The questionnaire involved 12 questions categorized into three sections. The first section obtained demographical information while the second section collected data about the past medical history of the participants. Lastly, the third section aimed to assess the prevalence of nephrolithiasis among participants or any history of the condition among their families. Results A total of 1,043 participants were surveyed, of whom 533 were males (51.1%). The prevalence of kidney stones was reported in 98 individuals (9.4%) overall. Individuals in the age groups of 36-50, 51-60, and >60 years showed significantly more renal stone prevalence than those in younger age groups (p<0.001). The prevalence was found to be higher in participants who were smokers, diabetic, hypertensive, and those who suffered from inflammatory bowel disease (IBD), gout, chronic kidney disease (CKD), hyperthyroidism, and hyperparathyroidism. Participants who took calcium supplements or had a positive family history of renal stones were found to have a higher prevalence of renal stones as well. However, only hypertension, gout, and family history showed any statistical significance (p<0.05). Conclusions A direct correlation was observed between hypertension, gout, positive family history, and aging and an increased prevalence of kidney stones among the inhabitants of the Riyadh province. Therefore, we encourage the local authorities to raise awareness of kidney stones and their related risk factors among the general public. Moreover, further local studies need to be conducted to gain deeper insights into kidney stone prevalence, especially pertaining to associated comorbidities and the pattern of the disease itself.

Multimodality Imaging in Metabolic Syndrome: State-of-the-Art Review

Metabolic syndrome comprises a set of risk factors that include abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, low high-density lipoprotein levels, and high blood pressure, at least three of which must be fulfilled for diagnosis. Metabolic syndrome has been linked to an increased risk of cardiovascular disease and type 2 diabetes mellitus. Multimodality imaging plays an important role in metabolic syndrome, including diagnosis, risk stratification, and assessment of complications. CT and MRI are the primary tools for quantification of excess fat, including subcutaneous and visceral adipose tissue, as well as fat around organs, which are associated with increased cardiovascular risk. PET has been shown to detect signs of insulin resistance and may detect ectopic sites of brown fat. Cardiovascular disease is an important complication of metabolic syndrome, resulting in subclinical or symptomatic coronary artery disease, alterations in cardiac structure and function with potential progression to heart failure, and systemic vascular disease. CT angiography provides comprehensive evaluation of the coronary and systemic arteries, while cardiac MRI assesses cardiac structure, function, myocardial ischemia, and infarction. Liver damage results from a spectrum of nonalcoholic fatty liver disease ranging from steatosis to fibrosis and possible cirrhosis. US, CT, and MRI are useful in assessing steatosis and can be performed to detect and grade hepatic fibrosis, particularly using elastography techniques. Metabolic syndrome also has deleterious effects on the pancreas, kidney, gastrointestinal tract, and ovaries, including increased risk for several malignancies. Metabolic syndrome is associated with cerebral infarcts, best evaluated with MRI, and has been linked with cognitive decline. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Pickhardt in this issue.

Impact of Metabolic Syndrome on Post-Operative Infection in Patients Undergoing Flexible Ureteroscopy Lithotripsy

Background: To investigate retrospectively whether metabolic syndrome (MetS) of flexible ureteroscopy (fURS) lithotripsy can be used to predict post-operative infection. Patients and Methods: After screening, 1,110 patients who received fURS lithotripsy for upper urinary tract stones in our center between January 2015 and December 2022 were analyzed retrospectively. Patients were divided into MetS-positive group and MetS-negative group. Post-operative infection was divided into fever, urosepsis, and septic shock. Relevant data during the peri-operative period were collected. Univariable and multivariable logistic regression analyses were adopted to estimate the impact of metabolic syndrome on post-operative infection in patients undergoing fURS lithotripsy. Results: Among the 1,110 patients, 427 tested positive for MetS, whereas 683 tested negative. Eighty-eight patients suffered from fever (67 patients in the MetS-positive group and 21 in the MetS-negative group). Forty-nine patients had urosepsis (29 patients in the MetS-positive group and 20 in the MetS-negative group), of whom seven patients developed septic shock. No patient developed multiple organ failure or died because of infection. The prevalence of post-operative infections in the MetS-positive group was higher than that in the MetS-negative group (p < 0.001). Multivariable logistic regression analyses showed that diabetes mellitus, MetS-positive, positive urine culture, and longer operation time were positively correlated with post-operative fever. Positive MetS, positive urine culture, and longer operation time were strongly correlated with post-operative urosepsis. Conclusions: Metabolic syndrome was found to be associated with post-operative infection in patients undergoing fURS lithotripsy, suggesting it can serve as a predictive factor.

Metabolic syndrome: imaging features and clinical outcomes

Metabolic syndrome, which affects around a quarter of adults worldwide, is a group of metabolic abnormalities characterized mainly by insulin resistance and central adiposity. It is strongly correlated with cardiovascular and all-cause mortality. Early identification of the changes induced by metabolic syndrome in target organs and timely intervention (eg, weight reduction) can decrease morbidity and mortality. Imaging can monitor the main components of metabolic syndrome and identify early the development and progression of its sequelae in various organs. In this review, we discuss the imaging features across different modalities that can be used to evaluate changes due to metabolic syndrome, including fatty deposition in different organs, arterial stiffening, liver fibrosis, and cardiac dysfunction. Radiologists can play a vital role in recognizing and following these target organ injuries, which in turn can motivate lifestyle modification and therapeutic intervention.

Is it Safe to Continue Aspirin in Patients Undergoing Percutaneous Nephrolithotomy?

OBJECTIVE

To evaluate peri-operative outcomes in patients on chronic aspirin therapy undergoing percutaneous nephrolithotomy (PCNL), with and without discontinuation of aspirin. Anti-coagulation and anti-platelet therapy are contraindications for PCNL per American Urological Association guidelines due to bleeding risk. However, there is potentially increased cardiovascular risk with peri-procedural aspirin withdrawal.

METHODS

Patients on chronic aspirin undergoing PCNL between January 2014 and May 2019 were retrospectively reviewed and stratified by continued or discontinued aspirin >5 days preoperatively. Hematologic complications, transfusions, and thrombotic complications were assessed with logistic regression model.

RESULTS

Three hundred twenty-five patients on chronic aspirin therapy underwent PCNL-85 continued and 240 discontinued aspirin. There were no significant differences in hemoglobin change, estimated blood loss, transfusions, creatinine change, thrombotic complications, 30-days re-admissions, complications, or 30-day emergency department visits. Patients who continued aspirin had longer length of stay (1.6 vs 1.9 days, P = .03). American Society of Anesthesiologists (ASA) score of 3 (OR 3.2, P = .02, 95% confidence intervals (CI) [1.2-8.4]), ASA score of 4 (OR 4.0, P = .02, 95% CI [1.2-13.1]), Black race, and previous smoking (OR 2.1, P = .02, 95% CI [1.1-3.9]) was associated with continued aspirin. Body mass index ≥30 was associated with aspirin discontinuation (OR 0.9, P = .004, 95% CI [0.9-1.0]). Increased postoperative hematologic complications were associated with additional anticoagulation medication (OR 2.9, P = .04, 95% CI [1.0-4.4]).

CONCLUSION

Continued aspirin use did not increase in postoperative complications in patients undergoing PCNL. Patients who are on additional anticoagulation medication are at risk of hematologic complications.

High perirenal fat thickness predicts a greater risk of recurrence in Chinese patients with unilateral nephrolithiasis

INTRODUCTION

The aim of this study was to evaluate the association between recurrence-free survival (RFS) and perirenal fat thickness (PFT) in a cohort of Chinese population with unilateral nephrolithiasis.

METHODS

We retrospectively reviewed the medical records of 81 patients with unilateral nephrolithiasis in our center from January 2019 to June 2019. PFT measured on computed tomography (CT) scans was evaluated. Kaplan-Meier curves and log-rank tests were used to assess significant differences in RSF between high-PFT and low-PFT groups within sexes. Univariable and multivariable Cox regression analyses were used to evaluate the potential risk factors for renal stone recurrence.

RESULTS

High PFT was significantly associated with high BMI and hyperlipidemia (p = .003 and.047, respectively). The PFT of stone-bearing kidney was significantly greater than PFT of non-stone-bearing kidney (0.77 ± 0.60 cm vs. 0.67 ± 0.58 cm, p = .002) . During the follow-up periods (median 31 months), 21 (25.9%) patients experienced ipsilateral renal stone recurrence. In addition, Kaplan-Meier survival curves showed that patients with low PFT had a significant better RFS than those with high PFT (p = .012). In the univariable Cox analyses, male sex and high PFT were significantly associated with a poor RFS (p = .042 and .018, respectively). Moreover, both male sex and high PFT retained significance in the multivariable analyses (p = .045 and .020, respectively).

CONCLUSIONS

Our findings suggested that PFT is a noninvasive and feasible parameter, which may help in the risk stratification of renal stone recurrence in the follow-up periods.

Popular Diets and Kidney Stones

Popular diets often influence dietary patterns, which have different implications for kidney stone risk. Despite the wide variety of popular diets, some general principles can be gleaned from investigating their potential impact on nephrolithiasis. Plant-based diets, including Dietary Approaches to Stop Hypertension, Mediterranean, flexitarian, and vegetarian diets, may protect against nephrolithiasis when they consist largely of unprocessed plant foods, while carbohydrate-restricted diets (including high-protein diets and the ketogenic diet) may raise kidney stone risk. Patients should be advised to consume a diet rich in whole plants, particularly fruits and vegetables, and minimize their consumption of animal proteins. Accompanying fruits and vegetables that are higher in oxalate content with more water and some dairy intake may also be useful. (We address the oxalate content of fruits and vegetables further below). Calcium consumption is an important component of decreasing the risk of kidney stones, as higher dietary calcium from dairy or nondairy sources is independently associated with lower kidney stone risk. Patients should also be advised to be conscious of fat intake, as fat in the intestinal lumen may complex with calcium and therefore increase urinary oxalate excretion. Finally, patients should avoid consumption of processed foods, which often contain added fructose and high sodium content, two factors that increase kidney stone risk.

Higher weight-adjusted waist index is associated with increased likelihood of kidney stones

Objectives

The objective of this study was to evaluate the association between weight-adjusted waist index (WWI) and the prevalence of kidney stones among adults in the United States.

Methods

The cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2007-2018. A total of 31,344 participants were categorized into two groups: those with kidney stones and those without. WWI was determined by dividing waist circumference (cm) by the square root of body weight (kg). To examine the relationship between kidney stones and WWI, multivariate logistic regression models, smoothed curve fitting, and weighted generalized additive model (GAM) regression were employed. Subgroup analysis and interaction tests were conducted to explore the stability of this association across different groups.

Results

The final analysis comprised a total of 31,344 participants, including 2,928 individuals who had a history of kidney stones. In the fully adjusted model, an increase in WWI exhibited a positive correlation with the prevalence of kidney stones (OR=1.34, 95% CI: 1.18-1.51). When WWI was converted into quartiles (Q1-Q4), participants in the highest quartile (Q4) had a 69% greater risk of developing kidney stones compared to those in the lowest quartile (Q1) (OR=1.69, 95% CI: 1.28-2.25). This positive association was particularly notable among non-diabetic patients.

Conclusion

Our study demonstrates a significant positive association between weight-adjusted waist index levels and an elevated prevalence of kidney stones among US adults. Furthermore, this research highlights the potential utility of weight-adjusted waist index in the prevention of kidney stones in the overall population. This relationship is limited and further research is needed to test this hypothesis.

Univariable and multivariable mendelian randomization study revealed the modifiable risk factors of urolithiasis

BACKGROUND

Urolithiasis is a common urological disease with increasing incidence worldwide, and preventing its risk poses significant challenges. Here, we used Mendelian randomization (MR) framework to genetically assess the causal nature of multifaceted risk factors on urolithiasis.

METHODS

17 potential risk factors associated with urolithiasis were collected from recently published observational studies, which can be categorized basically into lifestyle factors and circulating biomarkers. The instrumental variables of risk factors were selected from large-scale genome-wide association studies (N ≤ 607,291). Summary-level data on urolithiasis were obtained from UK Biobank (UKB) (3,625 cases and 459,308 noncases) and the FinnGen consortium (5,347 cases and 213,445 noncases). The univariable and multivariable MR analyses were applied to evaluate the causal, independent effect of these potential risk factors upon urolithiasis. Effects from the two consortia were combined by the meta-analysis methods.

RESULTS

Higher genetically predicted sex hormone-binding globulin (SHBG, OR, 0.708; 95% CI, 0.555 to 0.903), estradiol (OR, 0.179; 95% CI, 0.042 to 0.751), tea intake (OR, 0.550; 95% CI, 0.345 to 0.878), alcoholic drinks per week (OR, 0.992; 95% CI, 0.987 to 0.997), and some physical activity (e.g., swimming, cycling, keeping fit, and bowling, OR, 0.054; 95% CI, 0.008 to 0.363) were significantly associated with a lower risk of urolithiasis. In the Multivariate Mendelian Randomization (MVMR) analyses, the significant causal associations between estradiol, SHBG, tea intake, and alcoholic drinks per week with urolithiasis were robust even after adjusting for potential confounding variables. However, the previously observed causal association between other exercises and urolithiasis was no longer significant after adjusting for these factors.

CONCLUSIONS

The univariable and multivariable MR findings highlight the independent and significant roles of estradiol, SHBG, tea intake, and alcoholic drinks per week in the development of urolithiasis, which might provide a deeper insight into urolithiasis risk factors and supply potential preventative strategies.

Association between alcohol and urolithiasis: a mendelian randomization study

The causal relationship between alcohol and urolithiasis remains uncertain, despite previous observational studies reporting an association between the two. To determine the causality, we conducted a two-sample Mendelian randomization (MR) analysis. In this study, we aimed to investigate the causal relationship between alcohol and kidney stones using a two-sample MR approach. Two sets of genetic instruments were utilized in the analysis, both of which were derived from publicly available genetic summary data. The first set consisted of 73 single-nucleotide polymorphisms (SNPs) robustly linked to alcohol intake frequency (AIF) and the second set was comprised of 69 SNPs associated with alcohol consumption (AC). Our MR analysis was performed using several methods including the inverse-variance weighted (IVW) method, weighted median method, MR-Egger regression, MR Pleiotropy RESidual Sum and Outlier test. Our results from the MR analysis revealed a borderline significant association between AIF and the risk of urolithiasis. This was established through the use of the IVW method (OR (95% CI) = 1.29 (1.02, 1.65), p = 0.036) and the weighted median approach (OR (95% CI) = 1.44 (1.10, 1.89), p = 0.008). The MR-Egger model also yielded similar risk estimates (OR (95% CI) = 1.39 (0.66, 2.93), p = 0.386), although the relationship was not statistically significant. Sixty-eight SNPs were identified as having a substantial and independent link with AC. However, the IVW approach revealed no significant effect of AC on the risk of urolithiasis (OR (95% CI) = 0.74 (0.48, 1.14), p = 0.173). The MR analysis suggested a potential causal association between alcohol intake frequency and the risk of urolithiasis, but not alcohol consumption.

Correlation of Great Chinese Famine Exposure During Early Life to Prevalence of Kidney Stone in Adulthood

Background

The Great Chinese Famine, as the famine of 1959-1961 was often known. Famine exposure during early life was proven to be associated with some kidney diseases but has not been studied with kidney stone. We aimed to investigate the relationship between exposure to the Great Chinese Famine in early life and the incidence of kidney stone in adulthood.

Methods

From 1 January 2017 to 31 December 2018, a total of 19,658 eligible adults were recruited in a cross-sectional survey who were born between 1 October 1952 and 30 September 1964 in Guangdong, China. Participants were separated into kidney stone and none-kidney stone groups based on kidney stone status. According to birth data, participants were divided into non-exposed, fetal-exposed, early-, mid-, and late-childhood-exposed groups. Multivariate logistic regression, subgroup analysis and interaction test were used to estimate the odds ratios (ORs) and confidence intervals (CIs) between famine exposure and kidney stone.

Results

In total, 19,658 (12,246 female, mean age 59.31 ± 3.68 years) subjects were enrolled, and 3219 (16.38%) participants with kidney stone. The prevalence of kidney in none-, fetal-, early-, mid-, and late-childhood-exposed groups were 645 (14.9%), 437 (15.9%), 676 (16.3%), 743 (17.0%), and 718 (17.6%), respectively (P<0.001). When compared with the unexposed group, the fully adjusted ORs for kidney stone from fetal-exposed, early-, mid- to late-childhood-exposed groups were 1.37 (95% CI: 1.13, 1.68, P=0.002), 1.98 (95% CI: 1.45, 2.72, P<0.001), 2.94 (95% CI: 1.96, 4.42, P<0.001), and 3.48 (95% CI: 2.11, 5.72, P<0.001), respectively (P for trend<0.001). Subgroup analyses revealed no interactions between the famine effect on kidney stones and body mass index, gender, smoking status, history of diabetes or hypertension (all P for interaction >0.05).

Conclusion

This study found that exposure to the Great Chinese Famine during early life was independently associated with the increased incidence of kidney stone in adulthood.

Association between obstructive sleep apnea and 24-h urine chemistry risk factors for urinary stone disease

The effect of obstructive sleep apnea (OSA) on 24-h urine parameters and resultant kidney stone risk is unknown. We sought to compare urinary lithogenic risk factors among patients with kidney stone disease with and without OSA. We performed a retrospective cohort study of adult patients with nephrolithiasis undergoing both polysomnography and 24-h urine analysis. Measures of acid load including gastrointestinal alkali absorption, urinary titratable acid, and net acid excretion were calculated from 24-h urine. We performed univariable comparisons of 24-h urine parameters between those with and without OSA and fit a multivariable linear regression model adjusting for age, sex, and BMI. Overall, there were 127 patients who underwent both polysomnography and a 24-h urine analysis from 2006 to 2018. There were 109 (86%) patients with OSA and 18 (14%) without. Patients with OSA were more commonly male, had greater BMI and had higher rates of hypertension. Patients with OSA had significantly higher levels of 24-h urinary oxalate, uric acid, sodium, potassium, phosphorous, chloride, and sulfate; higher supersaturation of uric acid; higher titratable acid, and net acid excretion; and lower urinary pH and supersaturation of calcium phosphate (p < 0.05). The difference in urinary pH and titratable acid, but not net acid excretion, remained significant when adjusting for BMI, age, and gender (both p = 0.02). OSA is associated with changes in urinary analytes that promote kidney stone formation, similar to those observed with obesity. After accounting for BMI, OSA is independently associated with lower urine pH and increased urinary titratable acid.

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.

Role, importance and assessment of dietary habits in urolithiasis patient

Urolithiasis, which prevalence is increasing, poses a risk for chronic kidney disease in patients. Dietary habits play a significant role in stone formation, growth and recurrence. Also, comorbidities and lifestyle changes are among the factors affecting stone formation. The next step should be to detect metabolic disorders, if any, with analyzes to be made after a detailed anamnesis, and to arrange the necessary treatment. Insufficient fluid intake is considered to be the main dietary risk factor for urolithiasis. A daily fluid intake of 2.5-3.0 L/day or diuresis of 2.0-2.5 L/day is recommended to prevent recurrence of kidney stones. Not all beverages are beneficial, and some may even increase the risk of stone formation. Dietary management, vitamins and supplements, physical activity are important components in reducing the risk of recurrent urolithiasis. A detailed dietary assessment is recommended as dietary habits affect the faith of the disease. In this review we evaluated the dietary approach of urolithiasis patients with and without comorbidities, the recommended daily fluid intake, vitamin supplementation, and relation of the urolithiasis with physical activity.

High ambient temperature increases the number of emergency visits for upper urolithiasis in Hefei City, China

Background

Few studies have examined the effect of ambient temperature on upper urolithiasis in developing countries, with even fewer considering individual factors.

Methods

The present study analyzed data on emergency department visits for upper urolithiasis from three hospital sites of a large hospital in Hefei, China, during 2016-2020. Data on environmental factors during the same period were also analyzed. A time series analysis employing a generalized Poisson regression model (GPRM) combined with a distributed lag non-linear model (DLNM) was conducted to evaluate the effect of ambient temperature on the number of emergency department visits for upper urolithiasis.

Results

We found that ambient temperatures above 9 °C were positively associated with the frequency of upper urolithiasis visits, with the relationship being most significant on the current day and with a one-day lag. In the single-day lag effect, the most significant relative risk (RR) for mild heat (75th percentile) and high heat (95th percentile) was 1.229 (95% CI: 1.100-1.373) and 1.337 (95% CI: 1.134-1.577), respectively. The cumulative lag effect was significantly higher than the single-day lag effect, with maximum relative risks (RRs) of 1.779 (95% CI: 1.356-2.335) and 2.498 (95% CI: 1.688-3.697), respectively. The maximum lag time was 7 days. RRs were also higher among women and individuals aged 30-44 years.

Conclusions

Increased ambient temperature is a risk factor for upper urolithiasis, and there is a hysteresis effect. Women and individuals aged 30-44 years are the most susceptible.

Correlates of nephrolithiasis in US black women: data from the black women's health study

Nephrolithiasis is a common urologic condition and a significant source of patient morbidity and healthcare expenditure. There are few epidemiologic studies of kidney stones focusing exclusively on Black women. We retrospectively assessed the prevalence and correlates of self-reported kidney stones within the Black Women's Health Study (BWHS). Descriptive statistics and multivariable logistic regression models were used to explore factors associated with nephrolithiasis. As of the 2005 follow-up questionnaire, a cumulative total of 1063 women among 43,178 reported ever being diagnosed with kidney stones for a prevalence of 2.64%. Women with a history of nephrolithiasis were older, slightly heavier, and were more likely to have a comorbid condition (e.g., type-2 diabetes, gallstones), drink alcohol, and consume a Western-style diet. A history of gallstone disease was associated with an odds ratio (OR) of 3.59 (95% confidence interval (CI) 3.09-4.17). The OR for consuming ≥ 7 alcoholic beverages/week, compared to none was 0.61 (0.39-0.94), while the OR for high adherence to the Western diet, compared to low adherence was 1.53 (1.23-1.90). Our findings are consistent with previous studies of primarily white populations relating lifestyle-associated risk factors with nephrolithiasis. Despite their lower prevalence of kidney stones, it is important to focus on vulnerable populations such as Black women given their disproportionate burden of metabolic conditions (e.g., obesity, diabetes) related to kidney stone disease.

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.

Effect of Two Different Dietary Weight Loss Strategies on Risk Factors for Urinary Stone Formation and Cardiometabolic Risk Profile in Overweight Women

Overweight has been suggested to increase the risk of kidney stone formation. Although weight reduction might affect risk factors for urolithiasis, findings on the impact of different dietary weight loss strategies are limited. This randomized, controlled study evaluated the effect of a conventional energy-restricted modified diet with (MR group) or without meal replacement (C group) on risk factors for stone formation in overweight women without a history of urolithiasis. Of 105 participants, 78 were included into the per-protocol analysis. Anthropometric, clinical, biochemical, and 24 h urinary parameters were collected at baseline and after 12 weeks. Although both dietary interventions resulted in a significant weight reduction, relative weight loss and rate of responders were higher in the MR group. Weight loss improved cardiometabolic risk profile in both groups. Unfortunately, the benefit of decreased GPT activity in the C group was offset by a significant increase in homocysteine and a decline in GFR. While the relative supersaturation of calcium oxalate decreased significantly in both groups, a significant decline in serum uric acid concentration and relative supersaturation of uric acid was observed only in the MR group. Finally, the energy-restricted modified diet with meal replacement showed significant advantages over the energy-restricted modified diet alone.

[Urolithiasis-Therapy and recurrence prevention taking into account gender-specific aspects]

The prevalence of urolithiasis is steadily increasing worldwide in both genders. Diet and lifestyle, such as the rising prevalence of obesity and other metabolic syndrome traits, are considered key factors in this trend. Gender differences as a result of interventional therapy for urolithiasis have not been observed. However, iatrogenic injury to the male urethra is considered the most common reason for urethral strictures after endourologic (stone) therapy. In contrast, sepsis, as the major cause of urinary stone-related mortality, is more frequently reported in women after ureterorenoscopy and percutaneous nephrolithotomy. There are also differences in the frequency of various types of stones between men and women. Calcium oxalate and uric acid stones are more commonly observed in men, while carbonate apatite and struvite are diagnosed more often in women. Urinary stone analysis is therefore paramount for successful recurrence prevention. Diagnosis is based on the assignment of patients to the low-risk or high-risk group. The medical nutrition and pharmacological measures for the therapy of the respective type of stone are based on the risk factors in 24 h urine samples. A personalized approach that accounts for gender differences could further improve treatment, and recurrence prevention decisions for urinary stones.

Association of functional genetic variants in TFF1 and nephrolithiasis risk in a Chinese population

Trefoil Factor 1 (TFF1) is considered to be able to inhibit the formation of kidney stone. However, genetic variants in TFF1 and corresponding function in kidney stone development are still not well studied. In this study, the discovery set including 230 cases and 250 controls was used to analyze the association between seven tagSNPs of TFF1 gene and the nephrolithiasis risk. Further evaluation was confirmed by the validation set comprising 307 cases and 461 controls. The consequences of the two-stage case–control study indicated that individuals with the rs3761376 A allele have significantly increased nephrolithiasis risk than those with the GG genotypes [adjusted odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.05–1.73]. Moreover, we also carried out a stratified analysis and found the increased nephrolithiasis risks at A allele among males, overweight individuals, no hypertensive individuals, nondiabetic individuals, smokers, and drinkers. In the following functional experiments, the notably lower expression of TFF1 was exhibited by the vectors carrying A allele compared with those carrying G allele in both luciferase (P = 0.022) and expression vectors (P = 0.041). In addition to tissue detection, we confirmed a significant inverse association of rs3761376 G > A and TFF1 gene expression (P < 0.001). These results suggest that TFF1 rs3761376 may serve as a potential biomarker to predict the risk of nephrolithiasis.

Physical Activity Reduces the Effect of High Body Mass Index on Kidney Stones in Diabetes Participants From the 2007–2018 NHANES Cycles: A Cross-Sectional Study

Background

Body mass index (BMI) is a vital risk factor for kidney stones, but physical activity may reduce the incidence of kidney stones. However, it remains unknown whether physical activity reduces the effect of high BMI on kidney stones in diabetes participants.

Methods

We included clinical information from 4,008 adult participants with diabetes from the National Health and Nutrition Examination Survey (NHANES) database from 2007 to 2018. Univariate and multivariate logistic regression analyses were used to analyze the relationship between BMI and kidney stones, as well as the risk of BMI and kidney stones in different physical activity subgroups.

Results

A total of 4,008 diabetic participants were included in this study, of whom 652 (16.3%) self-reported a history of kidney stones. Logistic regression analysis showed a positive association between BMI and kidney stones. After adjusting for other confounders, the adjusted ORs for the risk of kidney stones was 1.514 (95% CI, 1.134–2.022, p = 0.005) for participants with BMI ≥30 kg/m² among all participants; the risk of kidney stones was elevated (OR = 1.572, 95% CI, 1.134–2.022, p = 0.005) in group without physical activity, and a reduced risk (OR = 1.421, 95% CI, 0.847–2.382, p = 0.183) in the group with physical activity. Furthermore, similar results were found in most subgroups.

Conclusion

Our study suggests that high BMI is a risk factor for diabetes kidney stone participants and that physical activity may moderate this relationship to some extent.

Effects of metabolic syndrome on renal stone progression

PURPOSE

Studies on howmetabolic syndrome affects renal stone progression in untreated asymptomatic patients are lacking. Therefore, we investigated the effect of metabolic syndrome on changes in renal stone size.

MATERIALS AND METHODS

We retrospectively analyzed 820 patients with renal stones incidentally detected on CT during regular health examinations and who underwent follow-up CT evaluations for > 1 year. The patients were divided into two groups according to the presence of metabolic syndrome. Changes in stone size during the follow-up were assessed, and differences were compared according to various factors. Predictors of stone size change on CT were assessed using linear regression analysis.

RESULTS

Overall, 820 asymptomatic patients without a history of stone treatments and with a mean follow-up of 52.4 months were included. Of these, 104 (12.7%) had metabolic syndrome and 335 (40.9%) showed stone size increase during the follow-up. The stone size at diagnosis was not significantly different between patients with and without metabolic syndrome (225.3 ± 332.6 vs. 183.9 ± 310.2 mm³, p = 0.159); however, a significant difference was observed in the change in stone size at follow-up (148.5 ± 352.0 vs. 81.5 ± 222.4 mm³, p = 0.001). Multivariable analysis showed that age (β = - 0.11; - 5.92 to -0.69; p = 0.013), fasting glucose level ≥ 100 mg/dl (β = 0.11; 9.78-99.73; p = 0.017), and metabolic syndrome (β = 0.10; 9.78-99.73; p = 0.017) were factors predictive of stone size changes.

CONCLUSION

Metabolic syndrome, fasting glucose level ≥ 100 mg/dl and young age are positively related to renal stone size changes. Therefore, periodic follow-up and metabolic syndrome management are required in asymptomatic patients with renal stones, especially in young age.

Effect of obesity and metabolic health on urolithiasis: A nationwide population-based study

Purpose

To investigate the risk of symptomatic urolithiasis requiring surgical treatment according to obesity and metabolic health status using a nationwide dataset of the Korean population.

Materials and Methods

Of the 5,300,646 persons who underwent health examinations between the year 2009 and 2016, within one year after the health examination, 35,137 patients who underwent surgical treatment for urolithiasis were enrolled. Participants were classified as “obese” or “non-obese” using a body mass index (BMI) cutoff of 25 kg/m². People who developed ≥1 metabolic disease component in the index year were considered “metabolically unhealthy”, while those with none were considered “metabolically healthy”.

Results

Out of 34,330 participants excluding 843 missing, 16,509 (48.1%), 4,320 (12.6%), 6,456 (18.8%), and 7,045 (20.5%) subjects were classified into the metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO) group, respectively. Mean BMI was 22.1±1.9 kg/m², 22.9±1.6 kg/m², 26.9±1.8 kg/m², and 27.9±2.4 kg/m² respectively. After adjusting the age and sex, the subjects in the MUNO group had an HR (95% CI) of 1.192 (1.120–1.268), those in the MHO group, 1.242 (1.183–1.305), and those in the MUO group, 1.341 (1.278–1.407) for either extracorporeal shockwave lithotripsy or surgery, compared to those in the MHNO group.

Conclusions

Metabolically healthy, obese individuals have a higher risk of developing symptomatic urolithiasis than non-obese, unhealthy, but have a lower risk than obese, unhealthy. It suggests that metabolic health and obesity have collaborative effects, independently affecting the development of symptomatic urinary stone diseases.

Subcutaneous Adipose Tissue Accumulation Is an Independent Risk Factor of Urinary Stone in Young People

BACKGROUND

Urinary stones usually start at a young age and tend to recur. Therefore, preventing stone occurrence and recurrence in young people is crucial. We aimed to investigate the association between subcutaneous adipose tissue, visceral adipose tissue, and stone episodes in young people.

METHODS

We retrospectively studied patients aged below 40 years with kidney or ureteral stones. Data on demographic and metabolic characteristics, urolithiasis history, subcutaneous fat area (SFA), and visceral fat area (VFA) were collected. We evaluated the association between SFA or VFA and the occurrence or recurrence of stone episodes using binary logistic regression and Poisson regression analyses.

RESULTS

In total, 120 patients were included. Abdominal obesity, overweight or obesity, dyslipidemia, metabolic syndrome, SFA, and VFA increased with the number of stone episodes (all p < 0.05). The increase in SFA was independently associated with episode occurrence (p = 0.015). Patients with an SFA > 97 cm² had a higher risk of episode occurrence. SFA and VFA accumulation were independently associated with episode recurrence (all p < 0.05), and SFA had a stronger association than VFA did.

CONCLUSIONS

In young people, SFA accumulation is an independent and early risk factor for the occurrence and recurrence of stone episodes. Subcutaneous fat could be a convenient and effective indicator to assess the risk of stone episodes before the development of metabolic disorders.

A Systematic Review on Comparative Analyses between Ureteroscopic Lithotripsy and Shock-Wave Lithotripsy for Ureter Stone According to Stone Size

Background and Objectives: This systematic review and meta-analysis was conducted to analyze the treatment outcomes of shock wave lithotripsy (SWL) and ureteroscopic lithotripsy (URSL) according to the ureteral stone size. Materials and Methods: In this systematic review, relevant articles that compared SWL and URSL for treatment of ureteral stones were identified. Articles were selected from four English databases including Ovid-Medline, Ovid-EMBASE, the Cochrane Central Register of controlled Trials (Central), and Google Scholar. A quality assessment was carried out by our researchers independently using the Scottish Intercollegiate Guidelines Network (SIGN). A total of 1325 studies were identified, but after removing duplicates, there remained 733 studies. Of these studies, 439 were excluded, 294 were screened, and 18 met the study eligibility criteria. Results: In randomized control trial (RCT) studies, URSL showed significantly higher SFR than SWL (p < 0.01, OR= 0.40, 95% CI 0.30–0.55, I² = 29%). The same results were shown in sub-group analysis according to the size of the stone (<1 cm: p < 0.01, OR = 0.40, 95% CI 0.25–0.63; >1 cm: p < 0.01, OR = 0.38, 95% CI 0.19–0.74, I² = 55%; not specified: p < 0.01, OR = 0.43, 95% CI 0.25–0.72, I² = 70%). In the non-RCT studies, the effectiveness of the URSL was significantly superior to that of SWL (p < 0.01, OR = 0.33, 95% CI 0.21–0.52, I² = 83%). Retreatment rate was significantly lower in URSL than in SWL regardless of stone size (p < 0.01, OR = 10.22, 95% CI 6.76–15.43, I² = 54%). Conclusions: Meta-analysis results show that SFR was higher than SWL in URSL and that URSL was superior to SWL in retreatment rate. However, more randomized trials are required to identify definitive conclusions.

Decision-Making, Preference, and Treatment Choice for Asymptomatic Renal Stones-Balancing Benefit and Risk of Observation and Surgical Intervention: A Real-World Survey Using Social Media Platform

Introduction: The burden of kidney stone disease has risen, and several treatment options now exist. We wanted to evaluate the preference and treatment choices based on the information provided for management of hypothetical 8 and 15 mm renal stone, and factors that influenced their decision. Materials and Methods: An online questionnaire to investigate trends in decision-making for two hypothesized scenarios of asymptomatic kidney stones (8 and 15 mm) was formatted online in Microsoft Forms and posted on social media (Facebook) in Europe. The ethical approval was obtained from the University Ethics Committee, and data were collected from general public between September and November 2020. Results: A total of 476 participants of different age and background answered the survey with a male:female ratio of 1:2.7. The age groups were categorized as 18-25 years (n = 149), 26-49 years (n = 192), and 50+ years (n = 135). In the 8 mm scenario, 107 of the 476 participants (22.5%) chose observation, 249 (52.3%) chose extracorporeal shockwave lithotripsy (SWL) and 120 (25.2%) opted for ureteroscopy (URS). In the 15 mm scenario, 194 participants chose SWL treatment (40.8%), 216 (45.4%) URS, and 66 (13.9%) preferred percutaneous nephrolithotomy. The influencing factors were success rate, complication risk and invasiveness of the procedure. On comparison to 8 mm stone, while stent avoidance and activity limitation were considered less important with 15 mm stone (p < 0.001), complication rates were considered more important (p < 0.001). Conclusion: More than one treatment choice for kidney stones often exists and clinicians must take patient choice into account via an informed decision-making process. While some might accept a higher risk of invasiveness and complications for higher stone-free rate, others might have a more conservative approach to this. It is about time that urologists take patient priorities and concerns into account and perhaps use Patient Reported Outcome Measures in addition to clinical outcomes when comparing treatment success.

Association between hyperlipidemia and calcium oxalate lower urinary tract uroliths in dogs

Background

Metabolic syndrome is associated with formation of calcium oxalate (CaOx) uroliths in humans.

Objectives

To investigate the association between obesity and hyperlipidemia with CaOx lower urinary tract uroliths in client‐owned dogs.

Animals

Dogs with (n = 55, U [uroliths]‐dogs) and without (n = 39, UF [uroliths‐free]‐dogs) CaOx lower urinary tract uroliths.

Methods

Case‐control study. U‐dogs were retrospectively enrolled and compared to UF‐dogs. Body condition score (BCS; 1‐9 scoring scale), serum triglyceride (TG) and total cholesterol (CH) concentrations and glycemia (after >12‐hour food withholding) were recorded in both groups.

Results

On univariate logistic regression, when excluding Miniature Schnauzers, odds of having uroliths increased by a factor of 3.32 (95% CI 1.38‐11.12) for each mmol/L of TG (P = .027), of 39 (95% CI 9.27‐293.22) for each mmol/L of glycemia (P < .0001), and of 2.43 (95% CI 1.45‐4.45) per unit of BCS (P = .002). In multivariable models, the effect of TG was retained when all breeds were included for analysis and odds of having uroliths increased by a factor of 4.34 per mmol/L of TG (95% CI 1.45‐19.99; P = .02).

Conclusions and Clinical Importance

Serum lipid screening in dogs diagnosed with CaOx uroliths might be recommended to improve their medical staging and management.

Association of Urine Findings with Metabolic Syndrome Traits in a Population of Patients with Nephrolithiasis

Background

The odds of nephrolithiasis increase with more metabolic syndrome (MetS) traits. We evaluated associations of metabolic and dietary factors from urine studies and stone composition with MetS traits in a large cohort of stone-forming patients.

Methods

Patients >18 years old who were evaluated for stones with 24-hour urine collections between July 2009 and December 2018 had their records reviewed retrospectively. Patient factors, laboratory values, and diagnoses were identified within 6 months of urine collection and stone composition within 1 year. Four groups with none, one, two, and three or four MetS traits (hypertension, obesity, dyslipidemia, and diabetes) were evaluated. Trends across groups were tested using linear contrasts in analysis of variance and analysis of covariance.

Results

A total of 1473 patients met the inclusion criteria (835 with stone composition). MetS groups were 684 with no traits, 425 with one trait, 211 with two traits, and 153 with three or four traits. There were no differences among groups for urine volume, calcium, or ammonium excretion. There was a significant trend (P<0.001) for more MetS traits being associated with decreasing urine pH, increasing age, calculated dietary protein, urine uric acid (UA), oxalate, citrate, titratable acid phosphate, net acid excretion, and UA supersaturation. The ratio of ammonium to net acid excretion did not differ among the groups. After adjustment for protein intake, the fall in urine pH remained strong, while the upward trend in acid excretion was lost. Calcium oxalate stones were most common, but there was a trend for more UA (P<0.001) and fewer calcium phosphate (P=0.09) and calcium oxalate stones (P=0.01) with more MetS traits.

Conclusions

Stone-forming patients with MetS have a defined pattern of metabolic and dietary risk factors that contribute to an increased risk of stone formation, including higher acid excretion, largely the result of greater protein intake, and lower urine pH.

Incidence and correlation of metabolic syndrome and kidney stones in a healthy screening population

Background

To study the incidence of metabolic syndrome (MetS) and kidney stones in a healthy screening population and to explore the correlation between them.

Methods

The physical examination data of 11,827 people screened at the First Affiliated Hospital of Soochow University from August 2019 to July 2020 were analyzed. MetS diagnostic criteria were based on the 2004 guidelines of Chinese Diabetes Society (CDS). Multivariate logistic regression was used to analyze the correlation between MetS and various characteristics and kidney stones. Trend analysis was represented by P value, and P<0.05 indicated statistical significance.

Results

The present study comprised 6,570 males (55.6%, aged 46.15±13.653 years) and 5,257 females (44.4%, aged 41.41±11.712 years). Of these, 1,036 (8.8%) had kidney stones and 1,552 (13.1%) had MetS. Among the MetS patients, 35.1% had a body mass index (BMI) ≥25, 27.7% had hypertension, 10.8% had hyperglycemia, and 31.2% had dyslipidemia. Kidney stone morbidity was 14.5% in the MetS group and 7.9% in the non-MetS group (P<0.05). As the number of MetS characteristics increased, kidney stone morbidity showed a linear increasing trend (P<0.05 for trend). With an increase in BMI and blood triglycerides (TG), and a decrease in lipoprotein cholesterol (HDL-C), the incidence of kidney stones had an increasing trend (P<0.05 for trend). Sex, age and MetS were independent risk factors for the occurrence of kidney stones, with and odds ratio (OR) of 1.493 [95% confidence interval (CI): 1.264–1.763] for MetS. Of the MetS characteristics, BMI ≥25 and blood pressure (BP) ≥140/90 mmHg were independent risk factors for kidney stones, with OR values of 1.209 (95% CI: 1.047–1.396) and 1.248 (95% CI: 1.071–1.453), respectively.

Conclusions

MetS is an independent risk factor for kidney stones. Appropriate medication and dietary advice may help to correct urinary metabolic abnormalities and prevent the recurrence of kidney stones.

Nutritional status assessed by the Controlling Nutritional Status (CONUT) score as a predictor of recurrence of urolithiasis

PURPOSE

We aimed to determine the influence of nutritional status on urinary metabolic abnormalities and stone recurrence in patients with urolithiasis.

MATERIALS AND METHODS

We analyzed data for 464 stone-formers and 464 propensity-score-matched control patients that had been collected between 2003 and 2015. Nutritional status was evaluated by use of the Controlling Nutritional Status (CONUT) score, and patients were placed into two CONUT score categories (0-1 and ≥2). Serum and 24-hour urinary metabolites were evaluated in 464 stone-formers. Kaplan-Meier and multivariate Cox regression analyses were performed to assess the influence of nutritional status on stone recurrence. Stone recurrence was defined as radiographic appearance of new stones during the follow-up period.

RESULTS

Stone-formers showed a higher prevalence of poor nutrition (CONUT score ≥2) than did the propensity-score-matched control patients (p<0.001). Stone-formers who had poor nutritional status had significantly lower 24-hour urinary calcium but higher oxalate excretion (each p<0.05). Kaplan-Meier estimates demonstrated that stone-formers with poor nutritional status also experienced stone recurrence more rapidly (log-rank test, p=0.014). Multivariate Cox regression revealed that poor nutritional status was independently associated with stone recurrence (hazard ratio, 1.736; 95% confidence interval, 1.041-2.896; p=0.034).

CONCLUSIONS

The CONUT score, an easily measured immunonutritional biomarker, is independently associated with a higher risk for stone recurrence in patients with urolithiasis. This implies that not only dietary excess, but also undernourished status, may be associated with aberrations in urine physicochemistry and stone recurrence.

The impact of metabolic syndrome components on urinary parameters and risk of stone formation

PURPOSE

To investigate the relationship between metabolic syndrome (MS) and urinary abnormalities in stone-forming patients. Additionally, to delineate whether severity of urinary derangements is impacted by the number of co-occurring MS components.

METHODS

Stone-forming patients who underwent initial metabolic workup prior to medical intervention at a comprehensive stone clinic were retrospectively reviewed and included in the study. Patients were given a six point (0-5) Metabolic Syndrome Severity Score (MSSS) based on the number of co-occurring MS components and split into six respective groups. Baseline clinical characteristics and metabolic profiles were compared between groups.

RESULTS

Four-hundred-ninety-five patients were included in the study. Median age and median BMI was 58 years and 27.26 kg/m², respectively. Several significant metabolic differences were noted, most notably a downward trend in median urinary pH (p < 0.001) and an upward trend in median urinary supersaturation uric acid (p < 0.001) across groups as MSSS increased. Multivariate analysis demonstrated an independent association between higher MSSS and increasing number of urinary abnormalities. A second multivariate analysis revealed that all MS components except hyperlipidemia were independently associated with low urinary pH. Additionally, obesity was independently associated with the greatest number of urinary abnormalities and had the strongest association with hyperuricosuria.

CONCLUSIONS

Prior research has attributed the strong association of nephrolithiasis and MS to high prevalence of UA nephrolithiasis and low urinary pH. Our findings indicate that all MS components with the exception of hyperlipidemia were independently associated with low urinary pH suggesting a mechanism independent from insulin resistance.

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.

Global Variations in the Mineral Content of Bottled Still and Sparkling Water and a Description of the Possible Impact on Nephrological and Urological Diseases

Kidney stone disease (KSD) is a complex disease. Besides the high risk of recurrence, its association with systemic disorders contributes to the burden of disease. Sufficient water intake is crucial for prevention of KSD, however, the mineral content of water might influence stone formation, bone health and cardiovascular (CVD) risk. This study aims to analyse the variations in mineral content of bottled drinking water worldwide to evaluate the differences and describes the possible impact on nephrological and urological diseases. The information regarding mineral composition (mg/L) on calcium, bicarbonate, magnesium, sodium and sulphates was read from the ingredients label on water bottles by visiting the supermarket or consulting the online shop. The bottled waters in two main supermarkets in 21 countries were included. The evaluation shows that on a global level the mineral composition of bottled drinkable water varies enormously. Median bicarbonate levels varied by factors of 12.6 and 57.3 for still and sparkling water, respectively. Median calcium levels varied by factors of 18.7 and 7.4 for still and sparkling water, respectively. As the mineral content of bottled drinking water varies enormously worldwide and mineral intake through water might influence stone formation, bone health and CVD risk, urologists and nephrologists should counsel their patients on an individual level regarding water intake.

Macrophage Function in Calcium Oxalate Kidney Stone Formation: A Systematic Review of Literature

Background

The global prevalence and recurrence rate of kidney stones is very high. Recent studies of Randall plaques and urinary components in vivo, and in vitro including gene manipulation, have attempted to reveal the pathogenesis of kidney stones. However, the evidence remains insufficient to facilitate the development of novel curative therapies. The involvement of renal and peripheral macrophages in inflammatory processes offers promise that might lead to the development of therapeutic targets. The present systematic literature review aimed to determine current consensus about the functions of macrophages in renal crystal development and suppression, and to synthesize evidence to provide a basis for future immunotherapy.

Methods

We systematically reviewed the literature during February 2021 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles investigating the relationship between macrophages and urolithiasis, particularly calcium oxalate (CaOx) stones, were extracted from PubMed, MEDLINE, Embase, and Scopus. Study subjects, languages, and publication dates were unrestricted. Two authors searched and screened the publications.

Results

Although several studies have applied mixed modalities, we selected 10, 12, and seven (total, n = 29) of 380 articles that respectively described cultured cells, animal models, and human samples.

The investigative trend has shifted to macrophage phenotypes and signaling pathways, including micro (m)-RNAs since the discovery of macrophage involvement in kidney stones in 1999. Earlier studies of mice-associated macrophages with the acceleration and suppression of renal crystal formation. Later studies found that pro-inflammatory M1- and anti-inflammatory M2-macrophages are involved. Studies of human-derived and other macrophages in vitro and ex vivo showed that M2-macrophages (stimulated by CSF-1, IL-4, and IL-13) can phagocytose CaOx crystals, which suppresses stone development. The signaling mechanisms that promote M2-like macrophage polarization toward CaOx nephrocalcinosis, include the NLRP3, PPARγ-miR-23-Irf1/Pknox1, miR-93-TLR4/IRF1, and miR-185-5p/CSF1 pathways.

Proteomic findings have indicated that patients who form kidney stones mainly express M1-like macrophage-related proteins, which might be due to CaOx stimulation of the macrophage exosomal pathway.

Conclusions

This systematic review provides an update regarding the current status of macrophage involvement in CaOx nephrolithiasis. Targeting M2-like macrophage function might offer a therapeutic strategy with which to prevent stones via crystal phagocytosis.

Urolithiasis prevalence in the Russian Federation: analysis of trends over a 15-year period

PURPOSE

To conduct a comparative analysis of the prevalence of urolithiasis in the Russian Federation.

METHODS

We analysed urolithiasis prevalence and incidence data from 2005 to 2019 (15 years) for the entire population of Russia. Data were provided by the 'Ministry of Health' of the Russian Federation. The prevalence and incidence of urolithiasis were collected and analysed for both adults and children for each region of the Russian Federation over this 15-year period. Statistical analysis was performed using the SPSS Statistics 21 software package (SPSS). Intergroup correlations and differences between samples in the studied parameters were considered significant at p < 0.05.

RESULTS

A total of 656,911 and 889,891 urolithiasis cases were observed in 2005 and 2019, respectively, an increase in urolithiasis prevalence of 35.4% for the study period, with the growth rate that was fairly uniform. The incidence of urolithiasis in the Russian Federation was 176,773 in 2005, while 205,414 new urolithiasis cases were recorded in 2019, with a clear tendency to a rising incidence of urolithiasis, an increase of 16.2% during the study period. The incidence per 100,000 in children remained stable during the entire period of analysis.

CONCLUSION

The incidence and prevalence of urolithiasis in the adult population steadily increased in all regions of the Russian Federation, while the incidence in children remained stable. The incidence of urolithiasis was associated with an increase in the incidence of diabetes mellitus, obesity and meat consumptions, highlighting the strong association of kidney stone disease with these risk factors.

Minimally Invasive Surgery for the Treatment of Ureteric Stones - State-of-the-Art Review

The landscape of managing ureteric stones has evolved over the last few decades and several treatment options exist depending on the stone size, location, and other patient and stone factors. While open surgery is now rarely performed, the use of medical expulsive therapy (MET) has been controversial and perhaps only recommended for large distal ureteric stones. The mainstay treatment balances between shockwave lithotripsy (SWL) and ureteroscopy (URS), with the latter usually recommended for larger stones. While the principles of ureteric stone management have remained largely unchanged, the modern era has generated new methods and means to deliver it. Advancements have occurred in all domains of endourology to try and refine treatment and balance it with cost, patient choice and quality of life. Dissemination of technologies and demonstration of their efficacy and safety will eventually result in new recommendations among international guidelines and evolution of new gold standards.

Crosstalk between Renal and Vascular Calcium Signaling: The Link between Nephrolithiasis and Vascular Calcification

Calcium (Ca²⁺) is an important mediator of multicellular homeostasis and is involved in several diseases. The interplay among the kidney, bone, intestine, and parathyroid gland in Ca²⁺ homeostasis is strictly modulated by numerous hormones and signaling pathways. The calcium-sensing receptor (CaSR) is a G protein–coupled receptor, that is expressed in calcitropic tissues such as the parathyroid gland and the kidney, plays a pivotal role in Ca²⁺ regulation. CaSR is important for renal Ca²⁺, as a mutation in this receptor leads to hypercalciuria and calcium nephrolithiasis. In addition, CaSR is also widely expressed in the vascular system, including vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) and participates in the process of vascular calcification. Aberrant Ca²⁺ sensing by the kidney and VSMCs, owing to altered CaSR expression or function, is associated with the formation of nephrolithiasis and vascular calcification. Based on emerging epidemiological evidence, patients with nephrolithiasis have a higher risk of vascular calcification, but the exact mechanism linking the two conditions is unclear. However, a dysregulation in Ca²⁺ homeostasis and dysfunction in CaSR might be the connection between the two. This review summarizes renal calcium handling and calcium signaling in the vascular system, with a special focus on the link between nephrolithiasis and vascular calcification.

A single day fasting may increase emergency room visits due to renal colic

We aimed to explore whether a single-day of fasting (SDF) increase emergency room (ER) visits due to renal colic (RC). We elected to concentrate on Yom-Kippur (i.e.: SDF), the holiest day in Judaism. Food and liquid consumption is prohibited during this day for 25 h, and an estimated 50–70% fasting rate is observed. SDF always takes place between mid-September and mid-October during which the temperature in the Middle-East ranges between 19 and 30 °C. ER visits for RC between 01/2012 and 11/2019 were reviewed, and the Gregorian days on which SDF occurred were retrieved. The number of ER visits for RC was compared between SDF and the surrounding days/months as well as to another single-day "standard" holiday (SDSH) that precedes SDF in 10 days and is not associated with fasting. Of 11,717 ER visits for RC, 8775 (74.9%) were males. Male:Female ratio was 3:1. The mean daily number of ER visits for RC during the 3 days following SDF was 6.66 ± 2.49, significantly higher compared with the mean annual daily visits (4.1 ± 2.27, p < 0.001), the mean daily visits during the week prior to SDF (5.27 ± 2.656, p = 0.032), and the mean daily visits during September (5.06 ± 2.659, p = 0.005), and October (4.78 ± 2.23, p < 0.001). The mean number of ER daily visits for RC during the 3 days following SDSH, 5.79 ± 2.84, did not differ compared with the mean daily visits during September and October (p = 0.207; p = 0.13, respectively). It was lower compared to SDF, however statistically insignificant (p = 0.285). A single-day fasting may increase ER visits for RC. The mechanism underlying this phenomenon is unknown.

Association Between Body Fat Mass and Kidney Stones in US Adults: Analysis of the National Health and Nutrition Examination Survey 2011-2018

BACKGROUND

The association between total and truncal body fat and kidney stone (KS) remains unclear.

OBJECTIVE

To evaluate the association between total and truncal body fat and KS in the US adult population.

DESIGN, SETTING, AND PARTICIPANTS

The National Health and Nutrition Examination Survey (NHANES) comprises a series of nationally representative cross-sectional surveys. Data from females and males aged 20-59 yr who participated in four 2-yr NHANES cycles between 2011 and 2018 were obtained.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Multivariable-adjusted logistic regression models were used to investigate the association between dual-energy x-ray absorptiometry (DXA) scan-measured total and truncal body fat percentage and mass with KS.

RESULTS AND LIMITATIONS

A total of 10 271 participants (50.3% females) were included. Weighted KS prevalence was 8.11% in femalesand 7.55% in males. In males, higher fat percentage was associated with higher odds of KS (per 5% total fat: odds ratio [OR] = 1.19, 95% confidence interval [CI] 1.08-1.32; per 5% truncal fat: OR = 1.22, 95% CI 1.10-1.35), particularly in those aged 40-59 yr (per 5% total fat: OR = 1.36, 95% CI 1.16-1.59; per 5% truncal fat: OR = 1.41, 95% CI 1.20-1.65, p-interaction < 0.05). In females, higher fat percentage was associated with higher odds of KS overall (per 5% total fat: OR = 1.23, 95% CI 1.10-1.37; per 5% truncal fat: OR = 1.20, 95% CI 1.08-1.33) and in both age groups (20-39 and 40-59 yr, p-interaction > 0.05). The observed associations were stronger in "other" ethnicities and non-Hispanic white. Similar patterns were observed for per 5 kg body fat mass.

CONCLUSIONS

Total and truncal fat parameters are associated with a higher prevalence of KS in adult females and males who are ≥40 yr old. Truncal fat mass may be at least equal or superior to total fat mass in assessing the association of body fat with KS. Further studies are warranted to elaborate on the pathophysiologic mechanism of this association to decrease the prevalence of KS.

PATIENT SUMMARY

Total and truncal body fat are associated with a higher prevalence of kidney stone (KS) in adult females and males aged ≥40 yr. Truncal fat mass may be similar or superior to total fat mass in assessing the association between body fat and KS.

Role of urinary biomarkers for diagnosis and prognosis of kidney stone disease

PURPOSE OF REVIEW

Urinary biomarkers such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1) and N-acetyl-B-D-glucosamindase (NAG) are recognised as being useful for the detection of kidney tubular damage but their role in the diagnosis and prognosis of kidney stone disease (KSD) is still unknown. To clarify this, we performed a systematic review of literature in accordance with Cochrane methodology from inception to September 2020.

RECENT FINDINGS

Twelve studies were included and a variety of urinary biomarkers (KIM-1, NGAL, NAG, proteins/peptides, cytokines, CA19-9) were measured in a total of 998 patients with KSD. Despite some contradicting studies, majority of the biomarkers studied showed a significant rise in patients with KSD compared to healthy controls, with levels decreasing after their surgical management, noticed as early as 4 h postprocedure. There was limited evidence of correlation with stone burden and elevated levels were also associated with hydronephrosis and superimposed infections.

SUMMARY

Urinary biomarkers could be used in the diagnosis, prognosis and stone-treatment response in patients with KSD. However, as novel indicators, they may not be reliable as the sole diagnostic or prognostic tool for KSD as they are readily confounded by other causes of kidney injury. Further studies are needed to determine their ability to separate KSD from other causes of obstructive uropathy and acute renal injury.

Variations in the mineral content of bottled 'carbonated or sparkling' water across Europe: a comparison of 126 brands across 10 countries

Introduction

Kidney stone disease is a common disease with high recurrence rates. Sufficient intake of water is the cornerstone in primary prevention of stone disease. However, the mineral composition of water can affect urinary minerals and influence stone formation. The aim of this study is to assess the variation in the mineral composition of bottled sparkling or carbonated drinking water across Europe.

Material and methods

The two largest supermarket chains in each participating country were visited to obtain data on mineral composition regarding bicarbonate, calcium, magnesium, potassium, sodium and sulphates of sparkling or carbonated waters by reading the ingredient labels on the bottles supplied by the manufacturers. Alternatively, the web-shops of these supermarkets were consulted.

Results

In total, 126 sparkling water brands across ten European countries were analysed regarding mineral composition. The median concentrations per mineral varied greatly. The greatest variation in median mineral content was found for sodium and sulphates with levels ranging from 3.1 mg/l to 63.0 mg/l and 6.0 mg/l to 263.0 mg/l respectively. A wide distribution of calcium content was found in Switzerland, with calcium levels reaching up to 581.6 mg/l.

Conclusions

This study confirms that the mineral composition of sparkling or carbonated water varies greatly across Europe. Patients with kidney stone disease should be aware that the mineral content of water may influence stone formation and be mindful of the great variation that exists between different water brands. Mineral water can be a source of potential promotors or inhibitors of stone formation and patients and urologists need to be mindful of this.

A high basal metabolic rate is an independent predictor of stone recurrence in obese patients

Purpose

Basal metabolic rate (BMR) is an indicator of overall body metabolism and may portend unique aberrations in urine physico-chemistry and stone recurrence. The present study examined the effect of predicted BMR on 24 hours urinary metabolic profiles and stone recurrence in obese stone patients.

Materials and Methods

Data from 308 obese patients (body mass index [BMI] ≥30 kg/m²) diagnosed with urinary stone disease between 2003 and 2015 were analyzed retrospectively. BMR was calculated using the Harris–Benedict equation, and patients were classified into two predicted BMR categories (<1,145 kcal/day, ≥1,145 kcal/day). Urinary metabolic parameters and risk of stone recurrence were compared between the two groups.

Results

The high BMR group was more likely to be younger and female, and to have a high BMI and lower incidence of diabetes than the low BMR group (each p<0.05). There was a positive correlation between BMR and 24 hours urinary sodium, uric acid, and phosphate excretion. The amounts of stone-forming constituents such as calcium and uric acid were significantly higher in the high BMR group. Kaplan–Meier estimates showed that the high BMR group had a significantly shorter stone recurrence-free period than the low BMR group (log-rank test, p<0.001). Multivariate Cox regression analyses revealed that predicted BMR was an independent factor of stone recurrence (hazard ratio, 2.759; 95% confidence interval, 1.413–5.386; p=0.003).

Conclusions

BMR may be an easily measured parameter that can be used to identify risk of stone recurrence in obese stone patients.