The role of fluid intake in the prevention of kidney stone disease: A systematic review over the last two decades

Therapeutic Potential of Ketogenic Interventions for Autosomal-Dominant Polycystic Kidney Disease: A Systematic Review

BACKGROUND

Recent findings have highlighted that abnormal energy metabolism is a key feature of autosomal-dominant polycystic kidney disease (ADPKD). Emerging evidence suggests that nutritional ketosis could offer therapeutic benefits, including potentially slowing or even reversing disease progression. This systematic review aims to synthesise the literature on ketogenic interventions to evaluate the impact in ADPKD.

METHODS

A systematic search was conducted in Medline, Embase, and Scopus using relevant Medical Subject Headings (MeSH) and keywords. Studies assessing ketogenic interventions in the management of ADPKD in both human and animal models were selected for data extraction and analysis.

RESULTS

Three animal reports and six human studies were identified. Ketogenic diets (KD) significantly slowed polycystic kidney disease (PKD) progression in rats with improved renal function and reduced cystic areas. There was reduced renal fibrosis and cell proliferation. The supplementation of beta-hydroxybutyrate (BHB) in rats also reduced PKD progression in a dose-dependent manner. Human studies (n = 129) on KD in ADPKD reported consistent body mass index (BMI) reduction across trials, with an average weight loss of ∼4 kg. Improvements in blood pressure were also noted. Ketosis was achieved in varying degrees. Effects on kidney function (eGFR) were beneficial. Results for kidney volume were mixed but most studies were underpowered for this outcome. Lipid profiles showed increases in total cholesterol (∼1 mmol/L) and LDL cholesterol (∼0.4 mmol/L) in most studies. Safety concerns such as "keto flu" symptoms, elevated uric acid levels, and occasional kidney stones were noted. Overall feasibility and adherence to the KD were rated positively by most participants.

CONCLUSIONS

Human studies are promising; however, they have been limited by small sample sizes and short durations. Larger, long-term trials are needed to assess the efficacy, adherence, and safety of ketogenic diets in people with ADPKD.

Non-invasive approaches to hydration assessment: a literature review

Traditional hydration assessment methods, while accurate, are often invasive and impractical for routine monitoring. In response, innovative non-invasive techniques such as bioelectrical impedance analysis (BIA), electrodermal activity (EDA), electrocardiogram (ECG) monitoring, and urine color charts have emerged, offering greater comfort and accessibility for patients. These methods use various types of sensors to capture a range of bio-signals, followed by machine learning-based classification or regression methods, providing real-time feedback on hydration status, which is crucial for effective management and prevention of urinary stones. This review explores the principles, applications, and efficacy of these non-invasive techniques, highlighting their potential to transform hydration monitoring in clinical and everyday settings. By facilitating improved patient compliance and enabling proactive hydration management, these approaches align with contemporary trends in personalized healthcare. This article presents a literature review on non-invasive approaches to hydration assessment, focusing on their significance in preventing kidney stone disease and enhancing kidney health.

Risk factors for nephrolithiasis formation: an umbrella review

OBJECTIVE

Nephrolithiasis is prevalent and burdensome worldwide. At present, evidence on the risk factors for nephrolithiasis is unconsolidated and the associations remain uncertain. The authors systematically evaluate the robustness of the meta-analytic evidence and aid more reliable interpretations of the epidemiological relationships.

METHODS

The authors conducted a comprehensive review of the meta-analyses, screened the included studies with the aid of the AMSTAR 2 evaluation tool, and then used R (4.1.1) software to perform data analysis to evaluate the association between candidate risk factors and kidney stones, and evaluated the credibility of the evidence of the association between risk factors and kidney stones according to the GRADE classification, and finally obtained the strength and effectiveness of the association.

RESULTS

The authors finally included 17 meta-analyses regarding 46 risk factors, 34 of which (73.9%) showed statistically significant association with nephrolithiasis. Among the significant associations, the authors found that waist circumference, BMI, dietary intake and fructose intake were positively correlated with the occurrence and development of nephrolithiasis. Caffeine, dietary fiber and DASH-diet showed a tendency to reduce kidney stones. Interestingly, calcium supplementation, dietary calcium, and vitamin D, which are widely believed to be responsible for stone formation, made no difference or even reduced the risk of nephrolithiasis.

CONCLUSIONS

The authors' study demonstrates the suggestive causal (central obesity, type 2 diabetes, gout, dietary sodium, fructose intake and higher temperatures) risk factors of nephrolithiasis. The authors also demonstrate the suggestive causal (coffee/alcohol/beer intake, dietary calcium and DASH-diet) protective factors of nephrolithiasis. To provide epidemiological basis for the treatment and prevention of nephrolithiasis.

Groundwater Hardness and Alkalinity As Risk Factors for Kidney Stone Disease in Alwar, India: An Ecological Study

INTRODUCTION

Rajasthan is a semi-arid state in India where people still use groundwater for drinking purposes. However, the quality of groundwater as compared to standards have not been studied in any details. This ecological study was done to study the groundwater quality parameters in the stone-belt states, compare the quality of groundwater in Alwar with the rest of Rajasthan, and study the morbidity profile of surgical in-patients in the same district, with special emphasis on kidney stone disease (KSDs).

METHODS

The morbidity profile of patients coming to the surgery department of a tertiary teaching hospital between January 2002 and June 2023 was obtained from the medical records department, and water quality data was obtained from the publicly available Water Resources Information System (WRIS) groundwater dataset for the year 2023. The dataset provided detailed information on the chemical parameters of water samples throughout the country that were evaluated to estimate the quality of groundwater.

RESULTS

It was found that the groundwater in Alwar is non-potable due to the presence of iron, alkalinity, magnesium, and total dissolved solids (TDS). Iron was estimated to be much higher than the acceptable limit of the Bureau of Indian Standards (BIS) drinking-water quality guidelines (0.3 mg/L). Similarly, most of the chemical parameters in the groundwaters of Rajasthan significantly exceeded the national average. The median electrical conductivity, fluoride, magnesium, sodium, hardness, alkalinity, and turbidity were found to be 1680 μS/cm, 1.05 parts per million (PPM), 41 PPM, 233 PPM, 330 PPM, 310 PPM, 988 PPM, respectively, which are above the WHO recommendations for drinking water guidelines.

CONCLUSIONS

The levels of iron and total alkalinity were significantly higher in the study district as compared to the rest of the state. Also, magnesium hardness and TDS levels were very high in the groundwater of the entire state of Rajasthan, making the population vulnerable to KSDs in the long run.

Renal calcification in children with renal tubular acidosis: What a paediatrician ‎should ‎know‎

Renal tubular acidosis (RTA) can lead to renal calcification in children, which can cause various complications and impair renal function. This review provides pediatricians with a comprehensive understanding of the relationship between RTA and renal calcification, highlighting essential aspects for clinical management. The article analyzed relevant studies to explore the prevalence, risk factors, underlying mechanisms, and clinical implications of renal calcification in children with RTA. Results show that distal RTA (type 1) is particularly associated with nephrocalcinosis, which presents a higher risk of renal calcification. However, there are limitations to the existing literature, including a small number of studies, heterogeneity in methodologies, and potential publication bias. Longitudinal data and control groups are also lacking, which limits our understanding of long-term outcomes and optimal management strategies for children with RTA and renal calcification. Pediatricians play a crucial role in the early diagnosis and management of RTA to mitigate the risk of renal calcification and associated complications. In addition, alkaline therapy remains a cornerstone in the treatment of RTA, aimed at correcting the acid-base imbalance and reducing the formation of kidney stones. Therefore, early diagnosis and appropriate therapeutic interventions are paramount in preventing and managing renal calcification to preserve renal function and improve long-term outcomes for affected children. Further research with larger sample sizes and rigorous methodologies is needed to optimize the clinical approach to renal calcification in the context of RTA in the pediatric population.

Bilateral Urinary Stones in a Transgender Woman: A Case Report in Lebanon

This case report presents a 38-year-old transgender woman, assigned male at birth, who presented with severe right flank pain associated with nausea and hematuria. After previously undergoing gender-affirming surgeries, including abdominoplasty, liposuction, breast augmentation, and reconstructive vaginal surgery, the patient developed bilateral ureteral and kidney stones leading to significant hydronephrosis. Bilateral double J insertion was performed following a computed tomography (CT) Uroscan. This was followed by flexible ureteroscopy and laser fragmentation of the stone bilaterally. The patient's anatomy was remarkable for the presence of neovagina and prostate. This case highlights the unique challenges and considerations in managing genitourinary complications in transgender individuals. The literature is limited in the Middle East concerning transgender individuals, hence the need to conduct further research and compile comprehensive case reports on transgender individuals in the Middle East in order to establish a robust database and draw meaningful epidemiological conclusions.

Kidney Stones in Epileptic Children Receiving Ketogenic Diet: Frequency and Risk Factors

BACKGROUND

Although it is a valuable option for children with drug-resistant epilepsy, ketogenic diet (KD) therapy is associated with several side effects. The frequency of kidney stones and risk factors for their development in epileptic children receiving KD is unclear. The aim of this study was to determine the frequency and risk factors for the development of renal stones in children receiving KD therapy.

METHODS

A total of 95 patients receiving KD were identified. Of these, seven patients were excluded from the study due to the duration of KD being less than 12 months. The remaining 88 children were enrolled in the study.

RESULTS

Renal stones were detected in 15 patients (17%), of which 12 (73.3%) received potassium citrate treatment. Two (13.3%) patients needed lithotripsy despite receiving potassium citrate treatment, and one of these, who received potassium citrate treatment for 5 months, developed acute vesicourethral reflux and underwent surgery. No patient discontinued KD due to renal stone development. The serum uric acid concentrations and urine calcium/creatinine ratio did not change significantly over the 24-month follow-up period. Age, gender, etiology, age at seizure onset, duration of KD, mobility status, use of topiramate or zonisamide, and the number of antiepileptic drugs used were not significantly different between patients with and without kidney stones.

CONCLUSION

Renal stone appears to be a common adverse effect of KD therapy. Although adequate hydration and potassium citrate treatment are effective in most patients, lithotripsy and surgery may be required in a minority of patients.

Patient perception and barriers with fluid hydration: a prospective face-to-face interview and counselling from a university hospital stone clinic

Introduction

Kidney stone disease (KSD) has a lifetime prevalence of up to 14% in the United Kingdom. Primary and secondary prevention of KSD via dietary intervention is a low-cost public health intervention and remains the best preventative strategy against urolithiasis.

Material and methods

This prospective study was conducted on kidney stone patients attending a stone clinic at our tertiary endourology centre. Patients were taken through a questionnaire, which was completed in the clinic by a trained specialist endourology nurse.

Results

A total of 259 patients completed the questionnaire. 141 (54.4%) had an active stone during the clinic visit with the remaining 118 (45.6%) with a history of stone treatment. Regarding barriers to fluid intake, 43 (16.6%) patients did not have a habit of drinking water or felt too bloated, 36 (13.9%) did not like the taste, 17 (6.6%) were not thirsty, 10 (3.9%) of patients were too busy. Of those who answered, 108 (46.8%) patients did not believe there was a link between fluid intake and stone formation. A belief of a link between fluid intake and stone formation significantly predicted fluid intake (p = 0.024) with people who did believe in this drinking less water.

Conclusions

There are numerous perceived barriers to adequate fluid intake, with almost half of all patients not believing that there is a link between fluid intake and stone formation. This misunderstanding may predict a lower fluid intake. More attention should therefore be focussed on patient education and primary prevention aspects to avoid kidney stone recurrence.

Effect of Blackcurrant Consumption on the Genitourinary System: A Literature Review

Both in vivo and in vitro studies have shown that functional plant-based food such as fruits, vegetables, and berries can enhance health, have preventive effects, and reduce the risk of several chronic diseases. This review discusses blackcurrant fruit usage in humans and experimental animals and its effect on the genitourinary system (GUS). This comprehensive review demonstrates that blackcurrants and their bioactive compounds possess medicinal and therapeutic properties related to the GUS. Emphasis in the literature has been placed on the bioavailability of the active blackcurrant components. Nonetheless, future clinical trials are needed to investigate and improve the bioavailability of blackcurrant phenolic compounds, such as anthocyanins, and to expand the evidence that active blackcurrant compounds can treat various genitourinary diseases.

Exploring the Potential Benefits of Natural Calcium-Rich Mineral Waters for Health and Wellness: A Systematic Review

This systematic review investigates the potential health and wellness benefits of natural calcium-rich mineral waters. It emphasizes the importance of dietary calcium sourced from natural mineral waters in promoting bone health, maintaining cardiovascular function, aiding in weight management, and enhancing overall well-being. The review process involved the comprehensive analysis of peer-reviewed articles, clinical trials, and experimental studies published within the last decade. Findings reveal that consuming calcium-rich mineral water can contribute significantly to daily calcium intake, particularly for those with lactose intolerance or individuals adhering to plant-based diets. The unique bioavailability of calcium from such waters also appears to enhance absorption, thus potentially offering an advantage over other calcium sources. The potential benefits extend to the cardiovascular system, with some studies indicating a reduction in blood pressure and the prevalence of cardiovascular diseases. Emerging evidence suggests that calcium-rich mineral water might have a role in body weight management, though further research is needed. The review identifies several areas requiring additional research, such as the potential interaction between calcium-rich mineral water and other dietary components, the effects on populations with specific health conditions, and the long-term effects of consumption. In conclusion, natural calcium-rich mineral waters show promise as a readily accessible and bioavailable sources of dietary calcium, potentially beneficial for a broad range of individuals. However, further investigation is required to fully understand its range of health impacts and define optimal intake levels.

Complementary and Alternative Medicine Usage and Quality of Life in Patients With Renal Colic Attack

Decreased quality of life is observed in individuals who fear surgery or experience severe symptoms due to urinary system stone disease (USSD). As a result, some patients seek complementary and alternative medicine (CAM) methods. This research evaluates preoperative CAM usage and its effects on quality of life for patients who experience renal colic (RC) due to USSD. The research was conducted between April 2020 and 2021 in the application and research center of a university. One hundred ten patients who were scheduled to have surgery due to USSD were included in the study. The data were collected using the "personal information form," "Use of CAM Methods of Individuals," and 36-item Short-Form Health Survey (SF-36) forms. Of research participants, 47.3% reported using at least one CAM method. The most common methods were exercise combined with phytotherapy (16.4%) and dietary supplements (15.5%). The proportion of participants who reported using 1 or multiple CAM methods for pain was 48.1%. The Social Functioning scores obtained from the SF-36 of the CAM users were statistically significant. For the participants who used a CAM method, the average Role-Emotional score obtained from the SF-36 was statistically significant. Health professionals should know which CAM methods patients may prefer and to what extent various CAM methods affect quality of life. More studies are needed to identify factors affecting the use of CAM methods in patients with RC attacks and to understand the relationship between CAM method(s) and quality of life.

Oxalate Homeostasis in Non-Stone-Forming Chronic Kidney Disease: A Review of Key Findings and Perspectives

Chronic kidney disease (CKD) is a significant global public health concern associated with high morbidity and mortality rates. The maintenance of oxalate homeostasis plays a critical role in preserving kidney health, particularly in the context of CKD. Although the relationship between oxalate and kidney stone formation has been extensively investigated, our understanding of oxalate homeostasis in non-stone-forming CKD remains limited. This review aims to present an updated analysis of the existing literature, focusing on the intricate mechanisms involved in oxalate homeostasis in patients with CKD. Furthermore, it explores the key factors that influence oxalate accumulation and discusses the potential role of oxalate in CKD progression and prognosis. The review also emphasizes the significance of the gut-kidney axis in CKD oxalate homeostasis and provides an overview of current therapeutic strategies, as well as potential future approaches. By consolidating important findings and perspectives, this review offers a comprehensive understanding of the present knowledge in this field and identifies promising avenues for further research.

Association between alcohol consumption and kidney stones in American adults: 2007-2016 NHANES

Purpose

To investigate the association between alcohol consumption and kidney stones in American adults.

Materials and methods

National Health and Nutrition Examination Survey (NHANES) datasets from 2007 to 2016 were utilized. Participants with a history of kidney stones and alcohol consumption aged 20 or older were included. Weighted proportions and regression analysis were used to assess the association between alcohol consumption and kidney stones by adjusting age, gender, race, marital status, education, recreational activities, smoking, and several comorbidities.

Results

Eleven population samples (Q1-Q11) were included from the NHANES dataset based on 11 questions compiled from the Alcohol Use Questionnaire (ALQ). In the fully adjusted regression model, none of these 11 samples demonstrated a significant association with urolithiasis, that is, alcohol consumption was not significantly associated with the incidence of kidney stones, even among heavy drinkers.

Conclusion

Alcohol consumption is not significantly associated with the prevalence of kidney stones. This finding requires a more adequate sample size and a more detailed review of the history of kidney stones to be further verified.

Mechanisms of the intestinal and urinary microbiome in kidney stone disease

Kidney stone disease affects ~10% of the global population and the incidence continues to rise owing to the associated global increase in the incidence of medical conditions associated with kidney stone disease including, for example, those comprising the metabolic syndrome. Considering that the intestinal microbiome has a substantial influence on host metabolism, that evidence has suggested that the intestinal microbiome might have a role in maintaining oxalate homeostasis and kidney stone disease is unsurprising. In addition, the discovery that urine is not sterile but, like other sites of the human body, harbours commensal bacterial species that collectively form a urinary microbiome, is an additional factor that might influence the induction of crystal formation and stone growth directly in the kidney. Collectively, the microbiomes of the host could influence kidney stone disease at multiple levels, including intestinal oxalate absorption and direct crystal formation in the kidneys.

Changes in Urine Composition and Risk of Kidney Stone Disease Following Bariatric Surgery: A Systematic Review over Last 2 Decades

PURPOSE OF REVIEW

The association of kidney stone disease (KSD) and gastrointestinal (GI) surgery has been well established. With a rising obesity crisis, we wanted to see the correlation of urinary composition in patients undergoing bariatric surgery and their risk of KSD. The objective of this paper is to perform a systematic review and meta-analysis of literature to evaluate the changes in urinary composition and risk of KSD following bariatric surgery.

RECENT FINDINGS

A total of seven studies (2498 patients) underwent bariatric surgery with a mean age of 46.7 years and a male:female ratio of 1:3. The most popular bariatric surgery was the Roux-en-Y procedure. Meta-analysis of the studies showed that significant decrease in urinary calcium, citrate, and urate, and increase in urinary oxalate. There was also a nonsignificant volume reduction in the post-operative cohort. The decrease in urinary citrate and increase in urinary oxalate are both predisposing factors of stone formation. There is strong evidence that bariatric surgery results in significant changes in urine composition in keeping with the increased risk of developing KSD. This identifies useful therapeutic targets in the prophylactic management of patients who have undergone bariatric surgery.

The Impact of Water and Other Fluids on Pediatric Nephrolithiasis

Pediatric nephrolithiasis cases have been on the rise in the past several years, resulting in increased healthcare costs and other burdens on the juveniles with this ailment. Recent research has shown that present trends in pediatric nephrolithiasis have changed as a result of fluid intake, including water consumption, nutrition, obesity prevalence, lifestyle, and imaging procedures. A specific cause, meanwhile, is still elusive. Trends in pediatric nephrolithiasis need to be thoroughly researched. Furthermore, variables specific to pediatric nephrolithiasis that could cause greater difficulties in an affected child elevate the level of worry with cumulative prevalence. Doctors should rigorously assess patients who present with kidney stones when they have dynamics such as varied clinical presentation, high recurrence of kidney stones linked to metabolic and urinary tract problems, and the potential existence of rare genetic kidney stone illnesses. This review aims to identify adaptive risk factors and anomalies that call for specialized treatment and prescription. More specifically, the major goals of medical and surgical treatments are to eliminate kidney stone risk and stop relapse while concurrently lowering interventional barriers. A dedicated nephrolithiasis clinic run by a pediatric nephrologist, nutritionist, urologist, and clinical nurse may sometimes be beneficial for patients in serious danger. Such a clinic offers significant chances to learn more about pediatric nephrolithiasis, which has been linked to water consumption and hence fosters urgently required study in this area.

Role of Citrus Fruit Juices in Prevention of Kidney Stone Disease (KSD): A Narrative Review

To explore the relationship between citrus fruit juices (oranges, grapefruits, and lemonades) and kidney stone disease (KSD).

METHODS

A systematic review was performed using the Medline, EMBASE, and Scopus databases, in concordance with the PRISMA checklist for all English, French, and Spanish language studies regarding the consumption of citrus fruit juices and the relationship to urinary stone disease. The main outcome of interest was the association of citrus fruit juices with KSD.

RESULTS

Thirteen articles met the criteria for inclusion in the final review. Three large epidemiological studies found that grapefruit juice was a risk factor for stone formation, while orange juice did not increase the risk for KSD. Ten small prospective clinical studies found that orange, grapefruit, and lemon juices all increased urinary citrate levels. Only orange and grapefruit juices had an alkalinizing effect and while lemon juice has a protective effect by raising urinary citrate levels, it lacked a significant alkalinizing effect on urine pH. Orange juice and grapefruit juices significantly increased urinary oxalate levels, while orange juice also had a high carbohydrate content.

CONCLUSION

While orange juice seems to play a protective role against stone formation, grapefruit was found to raise the risk of KSD in epidemiological studies but had a protective role in smaller clinical studies. Lemon juice had a smaller protective role than orange juice. Larger amounts of, as well as more accurate, data is needed before recommendations can be made and a high carbohydrate content in these juices needs to be taken into consideration.

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.

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.

Consumption of Tea, Alcohol, and Fruits and Risk of Kidney Stones: A Prospective Cohort Study in 0.5 Million Chinese Adults

A few prospective studies have suggested that tea, alcohol, and fruit consumption may reduce the risk of kidney stones. However, little is known whether such associations and their combined effect persist in Chinese adults, for whom the popular tea and alcohol drinks are different from those investigated in the aforementioned studies. The present study included 502,621 participants from the China Kadoorie Biobank (CKB). Information about tea, alcohol, and fruit consumption was self-reported at baseline. The first documented cases of kidney stones during follow-up were collected through linkage with the national health insurance system. Cox regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI). During a median of 11.1 years of follow-up, we collected 12,407 cases of kidney stones. After multivariable adjustment, tea, alcohol, and fruit consumption were found to be negatively associated with kidney stone risk, but the linear trend was only found in tea and fruit consumption. Compared with non-tea consumers, the HR (95% CI) for participants who drank ≥7 cups of tea per day was 0.73 (0.65-0.83). Compared with non-alcohol consumers, the HR (95% CI) was 0.79 (0.72-0.87) for participants who drank pure alcohol of 30.0-59.9 g per day but had no further decrease with a higher intake of alcohol. Compared with less-than-weekly consumers, the HR (95% CI) for daily fruit consumers was 0.81 (0.75-0.87). Even for those who did not drink alcohol excessively, increasing tea and fruit consumption could also independently reduce the stone risk. Among Chinese adults, tea, alcohol, and fruit consumption was associated with a lower risk of kidney stones.

Risk of Metabolic Syndrome in Kidney Stone Formers: A Comparative Cohort Study with a Median Follow-Up of 19 Years

Background: Kidney stone formers (SF) are more likely to develop diabetes mellitus (DM), but there is no study examining risk of metabolic syndrome (MetS) in this population. We aimed to describe the risk of MetS in SF compared to non-SF. Methods and Materials: SF referred to a tertiary referral metabolic centre in Southern England from 1990 to 2007, comparator patients were age, sex, and period (first stone) matched with 3:1 ratio from the same primary care database. SF with no documentation or previous MetS were excluded. Ethical approval was obtained and MetS was defined using the modified Association of American Clinical Endocrinologists (AACE) criteria. Analysis with cox proportional hazard regression. Results: In total, 828 SF were included after 1000 records were screened for inclusion, with 2484 age and sex matched non-SF comparators. Median follow-up was 19 years (interquartile range—IQR: 15–22) for both stone formers and stone-free comparators. SF were at significantly increased risk of developing MetS (hazard ratio—HR: 1.77; 95% confidence interval—CI: 1.55–2.03, p < 0.001). This effect was robust to adjustment for pre-existing components (HR: 1.91; 95% CI: 1.66–2.19, p < 0.001). Conclusions: Kidney stone formers are at increased risk of developing metabolic syndrome. Given the pathophysiological mechanism, the stone is likely a ‘symptom’ of an underlying metabolic abnormality, whether covert or overt. This has implications the risk of further stone events and cardiovascular disease.

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 content analysis of 'Water Apps' and prevention of urological diseases: Do apps really help?

Introduction

Maintaining hydration reduces incidence of kidney stone disease (KSD), chronic kidney disease (CKD) and urinary tract infections (UTIs). Mobile applications (apps) measuring hydration are gaining in usage, allowing users to monitor intake whilst also taking into account the signs and symptoms of dehydration. Our study looked at the water apps in the management and/or prevention of urological disease.

Material and methods

The original android app store (Google Play Store), and the Apple App Store (iOS App Store) were searched using the term ‘hydration’, ‘fluid’ and ‘water’. All apps from each distribution platform, with a minimum of 100 reviews, were then selected and analysed.

Results

After identification of 51 applications (13 from Apple App Store, and 38 from Google Play Store), 45 were free to download and 6 were paid (cost range: $2.19–$7.97). While none of the apps facilitated measurement of urine output and colour, 12 mentioned signs and symptoms of dehydration. Furthermore, when calculating required fluid intake, the level of activity was considered by 31 apps. With regards to information provision, only one of the apps included advice or education about urological conditions associated with poor hydration. None of the apps gave advice on hydration related to CKD and UTI.

Conclusions

Mobile phone apps are a well-established tool for measuring fluid intake. However, they provide little information regarding the importance of hydration, and don’t utilise other measures such as level of activity, urine output or colour. Considering the increasing popularity of fitness and hydration apps in our daily lives, the developers need to make them more comprehensive and informative.