Kidney stone disease: pathophysiology, investigation and medical treatment

Relationship between remnant cholesterol and risk of kidney stones in U.S. Adults: a 2007-2016 NHANES analysis

PURPOSE

Remnant cholesterol (RC) is the cholesterol content of triglyceride-rich lipoproteins. This study aimed to investigate the association between RC levels and kidney stones in U.S. adults.

METHODS

Data were obtained from the 2007 to 2016 National Health and Nutrition Examination Survey (NHANES). A total of 10,551 participants with complete data were included and analyzed in this study. Univariate and multivariate logistic regression analysis, restricted cubic spline function, subgroup analysis and mediation analysis were preformed to estimate the independent relationship between RC levels and kidney stones.

RESULTS

Participants with stone formation had higher levels of RC than those with without stone formation (25.78 ± 13.83 vs 23.27 ± 13.04, p< 0.001). The results of logistic regression analysis and dose-response risk curves revealed a positive nonlinear association between RC levels and risk of kidney stones [univariate: adjusted odds ratio (aOR) =2.388, 95% CI: 1.797-3.173, p< 0.001; multivariate: aOR = 1.424, 95% CI: 1.050-1.929, p = 0.023]. Compared with the discordantly low RC group, the discordantly high RC group was associated with increased risk of kidney stones (aOR = 1.185, 95% CI: 1.013-1.386, p= 0.034). Similar results were demonstrated according to the discordance of different clinical cut points. And metabolic syndrome parameters and vitamin D levels parallelly mediated the association between RC and kidney stone risk.

CONCLUSIONS

Higher RC levels were independently associated with an increased risk of kidney stone incidence.

The Safety Profile of Vitamin D Supplements Using Real-World Data from 445,493 Participants of the UK Biobank: Slightly Higher Hypercalcemia Prevalence but Neither Increased Risks of Kidney Stones nor Atherosclerosis

Background: Potential calcium-related adverse events of vitamin D supplement use have not been addressed in large-scale, real-world data so far. Methods: Leveraging data from the UK Biobank, encompassing 445,493 individuals aged 40-69, we examined associations of high 25-hydroxyvitamin (25(OH)D) levels ≥ 100 nmol/L and vitamin D supplementation with hypercalcemia (serum calcium > 2.6 mmol/L), kidney stones, and atherosclerosis assessments (pulse wave arterial stiffness index and carotid intima-medial thickness). Regression models were comprehensively adjusted for 49 covariates. Results: Approximately 1.5% of the participants had high 25(OH)D levels, 4.3% regularly used vitamin D supplements, and 20.4% reported regular multivitamin use. At baseline, the hypercalcemia prevalence was 1.6%, and 1.1% was diagnosed with kidney stones during follow-up. High 25(OH)D levels were neither associated with calcium-related adverse events nor atherosclerosis assessments. Vitamin D and multivitamin supplementation were associated with an increased prevalence of hypercalcemia (odds ratios and 95% confidence intervals: 1.46 [1.32-1.62] and 1.11 [1.04-1.18], respectively) but were neither associated with atherosclerosis nor future kidney stones. Conclusions: High 25(OH)D levels observable in routine care were not associated with any adverse outcome. Vitamin D users have a slightly higher prevalence of hypercalcemia, possibly due to co-supplementation with calcium, but without a higher atherosclerosis prevalence or risk of kidney stones.

Tranexamic acid for percutaneous nephrolithotomy: an abridged Cochrane review

OBJECTIVE

To assess the effects of tranexamic acid (TXA) in individuals with kidney stones undergoing percutaneous nephrolithotomy (PCNL).

PATIENTS AND METHODS

We performed a literature search of Cochrane Library, PubMed (including MEDLINE), Embase, Scopus, Global Index Medicus, trials registries, grey literature, and conference proceedings. We included randomised controlled trials (RCTs) that compared treatment with PCNL with administration of TXA to placebo (or no TXA) for patients aged ≥18 years. Two review authors independently classified studies and abstracted data. Primary outcomes were blood transfusion, stone-free rate (SFR), thromboembolic events (TEE). We rated the certainty of evidence (CoE) according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach using a minimally contextualised approach with pre-defined thresholds for minimally clinically important differences (MCID).

RESULTS

We included 10 RCTs assessing the effect of systemic TXA in PCNL vs placebo (or no TXA). Eight studies were published as full text. Based on an adjusted baseline risk of blood transfusion of 5.7%, systemic TXA may reduce blood transfusions (risk ratio [RR] 0.45, 95% confidence interval [CI] 0.27-0.76). Based on an adjusted baseline SFR of 75.7%, systemic TXA may increase SFR (RR 1.11, 95% CI 0.98-1.27). There is probably no difference in TEEs (risk difference 0.001, 95% CI -0.01 to 0.01). Systemic TXA may increase adverse events (AEs) (RR 5.22, 95% CI 0.52-52.72). Systemic TXA may have little to no effect on secondary interventions (RR 1.15, 95% CI 0.84-1.57). The CoE for most outcomes was assessed as low or very low.

CONCLUSIONS

Based on a body of evidence of 10 RCTs, we found that systemic TXA in PCNL may reduce blood transfusions, major surgical complications, and hospital length of stay, as well as improve the SFR; however, it may increase AEs. These findings should inform urologists and their patients in making informed decisions about the use of TXA in the setting of PCNL.

Nanomechanical properties of kidney stones, gallstones and oral stones compared with tap water scale by depth sensing indentation

This article focuses on a description of research performed to identify structural and mechanical properties differences between calculi in stones, such as gallstones, kidney stones, dental tartar, and saliva gland sialolite, were analyzed and compared with tap water stone, in order to set interrelations. In this study, biological hard pebble-like structures were analyzed and compared among them using Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), and Atomic Force Microscopy (AFM). In addition, Nanoindentation was used to obtain values as example in kidney stones the in; stiffness S = 27,827 ± 620 N/nm elastic modulus E = 27.3 ± 4.5 GPa, hardness H = 1.5 ± 0.5 GPa. Samples with the highest amounts of calcium and magnesium oxides were; Tap water stone (39.60%), followed by dental tartar (39.40%), saliva gland sialolite (29.20%), kidney stones (27.70%), and lastly the gallstones (0.30%). Kidney stones showed in particular, whewellite and kaoulinite crystallographic phases, that confers characteristics of greater crystallization with respect to the other stones. Kidney stones positioned in the major hardness stone in human body with 1.5 GPa. In general, samples with the highest amount of calcium oxides, also showed the highest mechanical properties of H and E. Microstructural characteristics and nano-hardness of tap water stone from drinking water where similar to those of dental tartar and saliva gland sialolite, more research still required to associate health concerns and tap water scale derived from drinking water known as hardwater.

Tranexamic acid for percutaneous nephrolithotomy

BACKGROUND

Percutaneous nephrolithotomy (PCNL) is the gold standard for the treatment of large kidney stones but comes with an increased risk of bleeding compared to other treatments, such as ureteroscopy and shock wave lithotripsy. Tranexamic acid (TXA) is an antifibrinolytic agent that has been used to reduce bleeding complications in other settings.

OBJECTIVES

To assess the effects of TXA in individuals with kidney stones undergoing PCNL.

SEARCH METHODS

We performed a comprehensive literature search of the Cochrane Library, PubMed (including MEDLINE), Embase, Scopus, Global Index Medicus, trials registries, other sources of the grey literature, and conference proceedings. We applied no restrictions on the language of publication nor publication status. The latest search date was 11 May 2023.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that compared treatment with PCNL with administration of TXA to placebo (or no TXA) for patients ≥ 18 years old.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified studies and abstracted data. Primary outcomes were: blood transfusion, stone-free rate (SFR), and thromboembolic events (TEEs). Secondary outcomes were: adverse events (AEs), secondary interventions, major surgical complications, minor surgical complications, unplanned hospitalizations or readmissions, and hospital length of stay (LOS). We performed statistical analyzes using a random-effects model. We rated the certainty of evidence (CoE) according to the GRADE approach using a minimally contextualized approach with predefined thresholds for minimally clinically important differences (MCIDs).

MAIN RESULTS

We analyzed 10 RCTs assessing the effect of systemic TXA in PCNL versus placebo (or no TXA) with 1883 randomized participants. Eight studies were published as full text. One was published in abstract proceedings, but it was separated into two separate studies for the purpose of our analyzes. Average stone surface area ranged 3.45 to 6.62 cm2. We also found a single RCT published in full text assessing the effects of topical TXA in PCNL versus placebo (or no TXA) with 400 randomized participants, the results of which are further described in the review. Here we focus only on the results of TXA used systemically. Blood transfusion - Based on a representative baseline risk of 5.7% for blood transfusions taken from a large presentative observational studies, systemic TXA may reduce blood transfusions (risk ratio (RR) 0.45, 95% confidence interval (CI) 0.27 to 0.76; I2 = 28%; 9 studies, 1353 participants; low CoE). We assumed an MCID of ≥ 2%. Based on 57 participants per 1000 with placebo (or no TXA) being transfused, this corresponds to 31 fewer (from 42 fewer to 14 fewer) participants being transfused per 1000. Stone-free rate - Based on a representative baseline risk of 75.7% for SFR, systemic TXA may increase SFRs (RR 1.11, 95% CI 0.98 to 1.27; I2 = 62%; 4 studies, 603 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 757 participants per 1000 being stone free with placebo (or no TXA), this corresponds to 83 more (from 15 fewer to 204 more) stone-free participants per 1000. Thromboembolic events - There is probably no difference in TEEs (risk difference (RD) 0.00, 95% CI -0.01 to 0.01; I2 = 0%; 6 studies, 841 participants; moderate CoE). We assumed an MCID of ≥ 2%. Since there were no thromboembolic events in intervention and/or control groups in 5 out of6 studies, we opted to assess a risk difference with systemic TXA for this outcome. Adverse events - Systemic TXA may increase AEs (RR 5.22, 95% CI 0.52 to 52.72; I2 = 75%; 4 studies, 602 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 23 participants per 1000 with placebo (or no TXA) having an adverse event, this corresponds to 98 more (from 11 fewer to 1000 more) participants with adverse events per 1000. Secondary interventions - Systemic TXA may have little to no effect on secondary interventions (RR 1.15, 95% CI 0.84 to 1.57; I2 = 0%; 2 studies, 319 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 278 participants per 1000 with placebo (or no TXA) having a secondary intervention, this corresponds to 42 more (from 44 fewer to 158 more) participants with secondary interventions per 1000. Major surgical complications - Based on a representative baseline risk for major surgical complications of 4.1%, systemic TXA may reduce major surgical complications (RR 0.36, 95% CI 0.21 to 0.62; I2 = 0%; 5 studies, 733 participants; moderate CoE). We assumed an MCID of ≥ 2%. Based on 41 participants per 1000 with placebo (or no TXA) having a major surgical complication, this corresponds to 26 fewer (from 32 fewer to 16 fewer) participants with major surgical complications per 1000. Minor surgical complications - Systemic TXA may reduce minor surgical complications (RR 0.71, 95% CI 0.45 to 1.10; I2 = 76%; 5 studies, 733 participants; low CoE). We assumed an MCID of ≥ 5%. Based on 396 participants per 1000 with placebo (or no TXA) having a minor surgical complication, this corresponds to 115 fewer (from 218 fewer to 40 more) participants with minor surgical complications per 1000. Unplanned hospitalizations or readmissions - We are very uncertain how unplanned hospitalizations or readmissions are affected (RR 1.55, 95% CI 0.45 to 5.31; I2 = not applicable; 1 study, 189 participants; very low CoE). We assumed an MCID of ≥ 2%. Hospital length of stay - Systemic TXA may reduce hospital LOS (mean difference 0.52 days lower, 95% CI 0.93 lower to 0.11 lower; I2 = 98%; 7 studies, 1151 participants; low CoE). We assumed an MCID of ≥ 0.5 days.

AUTHORS' CONCLUSIONS

Based on 10 RCTs with substantial methodological limitations that lowered all CoE of effect, we found that systemic TXA in PCNL may reduce blood transfusions, major and minor surgical complications, and hospital LOS, as well as improve SFRs; however, it may increase AEs. We are uncertain about the effects of systemic TXA on other outcomes. Findings of this review should assist urologists and their patients in making informed decisions about the use of TXA in the setting of PCNL.

Chemical Studies of Multicomponent Kidney Stones Using the Modern Advanced Research Methods

Defining the kidney stone composition is important for determining a treatment plan, understanding etiology and preventing recurrence of nephrolithiasis, which is considered as a common, civilization disease and a serious worldwide medical problem. The aim of this study was to investigate the morphology and chemical composition of multicomponent kidney stones. The identification methods such as infrared spectroscopy (FTIR), X-ray diffraction (XRD), and electron microscopy with the EDX detector were presented. The studies by the X-ray photoelectron spectroscopy (XPS) were also carried out for better understanding of their chemical structure. The chemical mapping by the FTIR microscopy was performed to show the distribution of individual chemical compounds that constitute the building blocks of kidney stones. The use of modern research methods with a particular emphasis on the spectroscopic methods allowed for a thorough examination of the subject of nephrolithiasis.

Efficacy and safety of various endosurgical procedures for management of large renal stone: a systemic review and network meta-analysis of randomised control trials

Urolithiasis is the most common benign urological health condition. It has contributed sizeable burden of morbidity, disability, and medical health expenditure worldwide. There is limited high level of evidence on the efficacy and safety of treatment options of large renal stones. This network meta-analysis has examined the effectiveness and safety of various large renal stone management strategies. Systematic review and network meta-analysis (NMA) study design was employed to summarize comparative randomized controlled trials on humans with a diagnosis of renal stone larger than or equal to 2 cm in size. Our searching strategy was based on the Population, Interventions, Comparison, Outcomes, and Study (PICOS) approach. Medline via PubMed, Embase, Google scholar, SCOPUS, Science Direct, Cochrane library, Web of Science, and ClinicalTrials.gov were searched from inception to March 2023 to find eligible articles. Data extraction, screening, selection and risk of bias assessment were conducted by two independent reviewers. We found ten randomised control trials which consists 2917 patients, nine of them were labeled as low risk and one article was high risk. This network meta-analysis found that SFR was 86% (95% CI 84-88%) for Mini-PCNL, 86% (95% CI 84-88%) for standard PCNL, 79% (95% CI:73-86%) for RIRS, and 67% (95%CI:49-81 for staged URS for management of large renal stone. Overall complication rate was 32% (95% CI 27-38%) for standard PCNL, 16% (95% CI 12-21%) for Mini-PCNL, and 11% (95% CI 7-16%) for RIRS. Mini-PCNL (RR = 1.14 (95% CI 1.01-1.27) and PCNL (RR = 1.13 (95% CI 1.01-1.27)) were statistically associated with a higher SFR compared to RIRS. The pooled mean hospital stays were 1.56 days (95% CI 0.93-2.19) for RIRS, 2.96 days (95% CI 1.78-4.14) for Mini-PCNL, 3.9 days (95% CI 2.9-4.83) for standard PCNL, and 3.66 (95% CI 1.13-6.2) for staged URS. Mini-PCNL and standard PCNL were the most effective treatment options with significant morbidity and length of hospital stay, while RIRS was the safest management option with acceptable SFR, low morbidity, and short hospital stay.

Prevalence and Risk Factors of Renal Stones Among the Bisha Population, Saudi Arabia

BACKGROUND

In urolithiasis, urinary calculi are formed in the urinary system. Stone development does not initially result in any symptoms, but later renal colic, flank pain, hematuria, obstruction of urine flow, and/or hydronephrosis may indicate renal stone disease. In addition to age, gender, ethnicity, and local climate, urolithiasis can be caused by several other factors. The prevalence and recurrence rate of kidney stone disease is rising globally, while few effective treatment options currently exist.

METHODS

Between June and October 2022, a cross-sectional study was conducted. An electronic questionnaire subdivided into three categories was used to determine the prevalence and identify the factors that increase the likelihood of developing urolithiasis among the population in Bisha. The collected data were reviewed and analyzed via IBM Corp. Released 2012. IBM SPSS Statistics for Windows, Version 21.0. Armonk, NY: IBM Corp.

RESULTS

A total of 1,002 participants filled out the questionnaire. The age of the participants ranged from 18 to over 60 years, with an average age of 26.1 ± 13.9 years. There were 451 female participants (45%), and 927 (92.5%) were Saudis. According to the participants' body mass index, 98 (9.8%) were underweight, 388 (38.7%) were normal weight, 300 (29.9%) were overweight, and 216 (21.6%) were obese. The total number of participants with urolithiasis was 161 (16.1%), and 420 (41.9%) had a family history of renal stones. Urolithiasis was found to be significantly associated with family history, smoking, diabetes, hypertension, hyperthyroidism, gout, and chronic kidney disease. Older age and female gender were also associated with the risk of having urolithiasis.

CONCLUSION

This study found urolithiasis to be highly prevalent among the Bisha population. In terms of risk factors, body mass index, smoking, and diabetes were the most significant. Based on the findings of this study, the authors recommend more public education regarding urolithiasis and its risk factors, emphasizing the importance of preventing the disease and the ways of treating urolithiasis through medical campaigns and social media.

Navigating nutrition and hydration care in the adult patient with short bowel syndrome

Attending diligently to the nutrition and hydration needs of patients with short bowel syndrome (SBS) is a key tenet of their care, both postoperatively and in the years that follow. For, without each, patients are left to themselves to navigate the nutrition consequences of SBS, including malnutrition, nutrient deficiencies, renal compromise, osteoporosis, fatigue, depression, and impaired quality of life. The intent of this review is to discuss the initial nutrition assessment, oral diet, hydration, and home nutrition support for the patient with SBS.

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

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

GeoBioMed perspectives on kidney stone recurrence from the reactive surface area of SWL-derived particles

Shock wave lithotripsy (SWL) is an effective and commonly applied clinical treatment for human kidney stones. Yet the success of SWL is counterbalanced by the risk of retained fragments causing recurrent stone formation, which may require retreatment. This study has applied GeoBioMed experimental and analytical approaches to determine the size frequency distribution, fracture patterns, and reactive surface area of SWL-derived particles within the context of their original crystal growth structure (crystalline architecture) as revealed by confocal autofluorescence (CAF) and super-resolution autofluorescence (SRAF) microscopy. Multiple calcium oxalate (CaOx) stones were removed from a Mayo Clinic patient using standard percutaneous nephrolithotomy (PCNL) and shock pulse lithotripsy (SPL). This produced approximately 4-12 mm-diameter PCNL-derived fragments that were experimentally treated ex vivo with SWL to form hundreds of smaller particles. Fractures propagated through the crystalline architecture of PCNL-derived fragments in a variety of geometric orientations to form rectangular, pointed, concentrically spalled, and irregular SWL-derived particles. Size frequency distributions ranged from fine silt (4-8 μm) to very fine pebbles (2-4 mm), according to the Wentworth grain size scale, with a mean size of fine sand (125-250 μm). Importantly, these SWL-derived particles are smaller than the 3-4 mm-diameter detection limit of clinical computed tomography (CT) techniques and can be retained on internal kidney membrane surfaces. This creates clinically undetectable crystallization seed points with extremely high reactive surface areas, which dramatically enhance the multiple events of crystallization and dissolution (diagenetic phase transitions) that may lead to the high rates of CaOx kidney stone recurrence after SWL treatment.

Variation in Tap Water Mineral Content in the United Kingdom: Is It Relevant for Kidney Stone Disease?

Introduction: The dissolved mineral content of drinking water can modify a number of excreted urinary parameters, with potential implications for kidney stone disease (KSD). The aim of this study is to investigate the variation in the mineral content of tap drinking water in the United Kingdom and discuss its implications for KSD. Methods: The mineral composition of tap water from cities across the United Kingdom was ascertained from publicly available water quality reports issued by local water supply companies using civic centre postcodes during 2021. Water variables, reported as 12-monthly average values, included total water hardness and concentrations of calcium, magnesium, sodium and sulphate. An unpaired t-test was undertaken to assess for regional differences in water composition across the United Kingdom. Results: Water composition data were available for 66 out of 76 cities in the United Kingdom: 45 in England, 8 in Scotland, 7 in Wales and 6 in Northern Ireland. The median water hardness in the United Kingdom was 120.59 mg/L CaCO3 equivalent (range 16.02−331.50), while the median concentrations of calcium, magnesium, sodium and sulphate were 30.46 mg/L (range 5.35−128.0), 3.62 mg/L (range 0.59−31.80), 14.72 mg/L (range 2.98−57.80) and 25.36 mg/L (range 2.86−112.43), respectively. Tap water in England was markedly harder than in Scotland (192.90 mg/L vs. 32.87 mg/L as CaCO3 equivalent; p < 0.001), which overall had the softest tap water with the lowest mineral content in the United Kingdom. Within England, the North West had the softest tap water, while the South East had the hardest water (70.00 mg/L vs. 285.75 mg/L as CaCO3 equivalent). Conclusions: Tap water mineral content varies significantly across the United Kingdom. Depending on where one lives, drinking 2−3 L of tap water can contribute over one-third of recommended daily calcium and magnesium requirements, with possible implications for KSD incidence and recurrence.

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

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

Size, Shape, and Phase of Nanoscale Uric Acid Particles

Uric acid particles are formed due to hyperuricemia, and previous works have focused on understanding the surface forces, crystallization, and growth of micron- and supermicron-sized particles. However, little to no work has furthered our understanding about uric acid nanonuclei that precipitate during the initial stages of kidney stone formation. In this work, we generate nanosized uric acid particles by evaporating saturated solution droplets of uric acid. Furthermore, we quantify the effects of drying rate on the morphology of uric acid nanonuclei. An aerosol droplet drying method generates uric acid nanoparticles in the size range of 20-200 nm from aqueous droplets (1-6 μm). Results show that uric acid nanonuclei are non-spherical with a shape factor value in the range of 1.1-1.4. The shape factor values change with drying rate and indicate that the nanoparticle morphology is greatly affected by drying kinetics. The nanonuclei are amorphous but can grow to form crystalline micron-sized particles. Indeed, a pre-crystallization phase was observed for heterogeneous nucleation of uric acid particles in the size range of a few hundred nanometers. Our findings show that the morphology of uric acid nanonuclei is significantly different from that of crystalline supermicron-sized particles. These new findings imply that the dissolution characteristics, surface properties, elimination, and medical treatment of uric acid nanonuclei formed during the initial stages of nucleation must be reconsidered.

Therapeutic potential of medicinal plants for the management of renal stones: A review

Kidney stone disease is the third most common urological ailment worldwide, people. The mechanism of stone formation includes: urine supersaturation, aggregation, retention, nucleation, and growth of crystals in the cells of the renal tubular epithelium. Kidney stones may cause extreme pain and blockage of urine flow. They are usually treated with conventional drugs and shock wave (ESWL) as well as a variety of medications that may cause several adverse effects. The remaining stone fragments and the risk of infection following ESWL are major challenges in the treatment of kidney stones. Recently, despite the emergence of modern drugs, medicinal plants have been recognized and utilized in many nations clinically due to their safety profile, efficiency, cultural acceptance, and fewer side effects than approved drugs. Medicinal plants are used in different cultures as a reliable source of natural remedies. The aim of this review is to provide comprehensive information about traditionally used plants as well as their scientifically proven pharmacological activities, their primary chemical ingredients, and potential mechanisms of action, such as analgesic, astringent, demulcent, diuretic activity, antioxidant activity, inhibition of the inflammatory process, nucleation inhibition, crystallization inhibition, inhibition of crystal aggregation, reducing , reducing stone size, and reducing urine supersaturation.

Performance of Dual-Source CT in Calculi Component Analysis: A Systematic Review and Meta-Analysis of 2151 Calculi

Objective:

To evaluate the performance of dual-source computed tomography (DSCT) in the component analysis of all types of calculi by doing a systematic review and meta-analysis.

Methods:

We searched MEDLINE, Embase, Scopus, and CNKI up to February 28, 2020, for in vivo studies investigating the performance of DSCT in the component analysis of calculi. We pooled the sensitivity, specificity, and areas under the summary receiver operating characteristic (AUROC) curves using a random-effect model in the meta-analysis. Publication bias was evaluated using Deek’s funnel plot asymmetry test.

Results:

This analysis included a total of 37 studies in 1840 patients with 2151 calculi (462 uric acid [UA], 1383 calcium oxalate [CaOx], 55 cystine [Cys], 197 hydroxyapatite [HA], and 54 struvite [SV]). Using DSCT, the pooled accuracy for diagnosing UA (sensitivity, 0.95; specificity, 0.99), CaOx (0.98; 0.93), Cys (0.99; 0.99), HA (0.91; 0.99), and SV (0.42; 0.98) was calculated, respectively. The AUROC value was 0.99, 0.99, 1.00, 0.99, and 0.93, respectively. The P values for publication bias test were .49, .70, .07, .04, and .19, respectively.

Conclusion:

Dual-source computed tomography has high sensitivity and specificity for the component analysis of UA, CaOx, Cys, and HA calculi in vivo. This tool may have the potential to replace the current analysis tool in vitro in diagnosing calculi.

Seasonal Variation in the Frequency of Presentation with Acute Ureteral Colic and Its Association with Meteorologic Factors

Introduction: A seasonal variation in the frequency of acute stone presentations has been observed in studies from the United States, Africa, and Asia. The increased incidence of acute stone presentations during periods of warm weather has been attributed to both the dehydrating effect of elevated temperatures and the vitamin D related increase in calciuria during periods of increased sunshine. The aim of this study is to establish whether the association between various meteorologic parameters and the frequency of acute stone presentations also exists in a European climate. Methods: All computed tomography kidneys, ureters and bladder scans performed by Emergency Departments within the Dublin Midland Hospital Group between June 2017 and September 2018 were identified from the national radiologic database. The date of scan in addition to stone parameters (site, size, and side) was recorded. These data were then correlated with weather recordings obtained from the Irish meteorologic office. Results: A total of 2441 patients were investigated for suspected renal colic during the study period of which 781 were confirmed to have ureteral stones. An increased frequency of acute stone presentations was observed during the summer months of both years (June, July, and August). Unexpectedly, the heat wave of summer 2018 was not associated with an increased frequency of nephrolithiasis compared with summer 2017. Conclusion: There is an increased frequency of acute nephrolithiasis during the summer months in Ireland. Health care services should be tailored to expect an increase in service needs during these periods of increased activity.

Seasonal variations in urinary calcium, volume, and vitamin d in kidney stone formers

OBJECTIVES

To investigate the seasonal variations in urinary calcium, serum vitamin D, and urinary volume in patients with a history of nephrolithiasis.

MATERIALS AND METHODS

Patients included were those who completed a 24-hour urine metabolic evaluation on two occasions; one in summer (June-Aug) and one in winter (Nov-Jan), and who had not started any medications or been instructed on dietary modifications in the interval between the two tests that may have impacted the results. Patients were excluded if they were on thiazide diuretics or were taking calcium and / or Vitamin D supplementation. Welch's t-test was used to compare the difference in average summer and winter values. Unpaired Student t-test was used to compare baseline parameters (age, BMI), and Paired Student t-test was used to compare average seasonal measurements in men vs. women.

RESULTS

136 patients were identified who were not taking calcium or vitamin D supplements or thiazide diuretics, and who were not instructed on dietary modifications in the interval between the two measured parameters. No significant differences were observed when comparing male to female baseline parameters of age or BMI (Table-1). Average 24-hour urine calcium was higher (226.60) in the winter than in summer (194.18) and was significant in males (p = 0.014) and females (p < 0.001). No significant seasonal difference was seen in 24-hour urine volume or serum vitamin D levels.

CONCLUSIONS

Urinary calcium is higher in winter months compared to summer months. As such, tailoring medical preventative strategies to the time of year may be helpful.

Kidney Stone Disease: An Update on Current Concepts

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

Occupational Heat Stress and Kidney Health: From Farms to Factories

Millions of workers around the world are exposed to high temperatures, intense physical activity, and lax labor practices that do not allow for sufficient rehydration breaks. The extent and consequences of heat exposure in different occupational settings, countries, and cultural contexts is not well studied. We conducted an in-depth review to examine the known effects of occupational heat stress on the kidney. We also examined methods of heat-stress assessment, strategies for prevention and mitigation, and the economic consequences of occupational heat stress. Our descriptive review summarizes emerging evidence that extreme occupational heat stress combined with chronic dehydration may contribute to the development of CKD and ultimately kidney failure. Rising global temperatures, coupled with decreasing access to clean drinking water, may exacerbate the effects of heat exposure in both outdoor and indoor workers who are exposed to chronic heat stress and recurrent dehydration. These changes create an urgent need for health researchers and industry to identify work practices that contribute to heat-stress nephropathy, and to test targeted, robust prevention and mitigation strategies. Preventing occupational heat stress presents a great challenge for a concerted multidisciplinary effort from employers, health authorities, engineers, researchers, and governments.

The Chronic Kidney Disease Water Intake Trial: Protocol of a Randomized Controlled Trial

Background:

In observational studies, drinking more water associates with a slower rate of kidney function decline; whether the same is true in a randomized controlled trial is unknown.

Objective:

To examine the 1-year effect of a higher vs usual water intake on estimated glomerular filtration rate (eGFR) in patients with chronic kidney disease.

Design:

Parallel-group randomized controlled trial.

Setting:

Nine centers in Ontario, Canada. Enrollment and randomization occurred between May 2013 and May 2016; follow-up for the primary outcome will continue until June 2017.

Participants:

Adults (n = 631) with stage 3 chronic kidney disease (eGFR 30-60 mL/min/1.73 m²) and microalbuminuria.

Intervention:

The high water intake group was coached to increase their oral water intake by 1.0 to 1.5 L/day (depending on sex and weight), over and above usual consumed beverages, for a period of 1 year. The control group was coached to maintain their usual water intake during this time.

Measures:

Participants provided 24-hour urine samples at baseline and at 6 and 12 months after randomization; urine samples were analyzed for volume, creatinine, osmolality, and the albumin-to-creatinine ratio. Blood samples were obtained at baseline and at 3- to 6-month intervals after randomization, and analyzed for creatinine, copeptin, osmolality, and electrolytes. Other measures collected included health-related quality of life, blood pressure, body mass index, and diet.

Primary outcome:

The between-group change in eGFR from baseline (prerandomization) to 12 months after randomization.

Secondary outcomes:

Change in plasma copeptin concentration, 24-hour urine albumin-to-creatinine ratio, measured creatinine clearance, estimated 5-year risk of kidney failure (using the 4-variable Kidney Failure Risk Equation), and health-related quality of life.

Planned analysis:

The primary analysis will follow an intention-to-treat approach. The between-group change in eGFR will be compared using linear regression. Supplementary analyses will examine alternative definitions of eGFR change, including annual percentage change, rate of decline, and rapid decline (a P value <0.05 will be interpreted as statistically significant if there is concordance with the primary outcome).

Trial Registration:

This randomized controlled trial has been registered at www.clinicaltrials.gov; government identifier: NCT01766687.

Incidence of and risk factors for nephrolithiasis in patients with gout and the general population, a cohort study

BACKGROUND

Nephrolithiasis (NL) is known to be associated with gout, although there are few comparative studies on risk and risk factors for NL in gout compared to population cohorts. In this cohort study we investigated: (1) overall incidence of NL in gout (cases) and general population controls; (2) risk and risk factors (common comorbidities and medications) for first-time NL in cases and controls separately.

METHODS

Cases (n = 29,968) and age-matched and sex-matched controls (n = 138,678) were identified from the regional healthcare database in western Sweden (VEGA). The analyzed risk factors (comorbidities and current medication use) for first-time NL, and socioeconomic factors were retrieved from VEGA and other national Swedish registers. For cases, follow up began on 1 January 2006 or on the first diagnosis of gout if this occurred later, and for controls on their index patient's first diagnosis of gout. Follow up ended on death, emigration or 31 December 2012. Incidence rates (IR) per 1000 person-years and hazard ratios (HR) were calculated. The incidence calculations were performed for cases (regardless of prior NL) and their controls. HRs with first occurrence of NL as outcome were calculated only in those without previous NL.

RESULTS

In cases there were 678 NL events (IR: 6.16 events per 1000 person-years (95% CI: 5.70-6.64) and in controls 2125 NL events (IR 3.85 events per 1000 person-years (95% CI: 3.69-4.02), resulting in an age-sex-adjusted incidence rate ratio of 1.60 (95% CI:1.47-1.74). Point estimates for predictive factors were similar in cases and controls, except for a significant interaction for losartan which increased the risk of NL only in controls (HR = 1.49 (95% CI: 1.03-2.14). Loop diuretics significantly decreased the risk of NL by 30-34% in both cases and controls. Further significant predictors of NL in gout cases were male sex, diabetes and obesity and in controls male sex and kidney disease.

CONCLUSIONS

The risk (age and sex adjusted) of NL was increased by 60% in cases compared to controls. None of the commonly used medications increased the risk of NL in gout patients.

Kidney stones: pathophysiology, diagnosis and management

The prevalence of kidney stones is increasing, and approximately 12 000 hospital admissions every year are due to this condition. This article will use a case study to focus on a patient diagnosed with a calcium oxalate kidney stone. It will discuss the affected structures in relation to kidney stones and describe the pathology of the condition. Investigations for kidney stones, differential diagnosis and diagnosis, possible complications and prognosis, will be discussed. Finally, a detailed account of management strategies for the patient with kidney stones will be given, looking at pain management, medical procedures and dietary interventions.

Nutritional Management of Kidney Stones (Nephrolithiasis)

The incidence of kidney stones is common in the United States and treatments for them are very costly. This review article provides information about epidemiology, mechanism, diagnosis, and pathophysiology of kidney stone formation, and methods for the evaluation of stone risks for new and follow-up patients. Adequate evaluation and management can prevent recurrence of stones. Kidney stone prevention should be individualized in both its medical and dietary management, keeping in mind the specific risks involved for each type of stones. Recognition of these risk factors and development of long-term management strategies for dealing with them are the most effective ways to prevent recurrence of kidney stones.

Treatment effect, adherence, and safety of high fluid intake for the prevention of incident and recurrent kidney stones: a systematic review and meta-analysis

BACKGROUND

The objective of this systematic review and meta-analysis were to evaluate the effectiveness of high fluid intake for the prevention of incident and recurrent kidney stones, as well as its adherence and safety.

METHODS

A literature search was performed encompassing 1980 through July 2014. Studies that reported relative risks, odds ratios, or hazard ratios comparing the risk of kidney stone events in patients with high vs inadequate fluid intake were included. Pooled risk ratios (RRs) and 95 % confidence intervals (CIs) were calculated using a random-effect, generic inverse variance method.

RESULTS

Nine studies [2 randomized controlled trials (RCTs) with 269 patients; 7 observational studies with 273,685 individuals] were included in the meta-analysis. Pooled RRs of kidney stones in individuals with high-fluid intake were 0.40 (95 % CI 0.20-0.79) and 0.49 (0.34-0.71) in RCTs and observational studies, respectively. High fluid intake was significantly associated with reduced risk of recurrent kidney stones: RRs 0.40 (95 % CI 0.20-0.79) and 0.20 (0.09-0.44) in RCTs and observational studies, respectively. Adherence and safety data on high fluid intake treatment were limited; 1 RCT reported no withdrawals due to adverse events.

CONCLUSION

This analysis demonstrated a significantly reduced risk of incident kidney stones among individuals with high fluid consumption. High fluid consumption also reduced the risk of recurrent kidney stones. Furthermore, the magnitude of risk reduction was high. Although increased water intake appears to be safe, future studies on its safety in patients with high risk of volume overload or hyponatremia may be indicated.

Effects of high doses of cholecalciferol in normal subjects: a randomized double-blinded, placebo-controlled trial

BACKGROUND

Vitamin D repletion with high doses of vitamin D is often recommended to patients and healthy subjects. The safety, especially concerning changes in urinary calcium excretion is of great importance.

METHODS

In a double-blinded, placebo-controlled study in 40 healthy volunteers, we examined the changes in mineral metabolism during supplementation with 3000 IU of oral cholecalciferol daily during 4 months.

RESULTS

Both 25(OH)vitamin D and 1,25(OH)2vitamin D increased significantly in the active treated group as compared to the placebo group (186% versus 14% (P<0.001) and 28% versus -8% (P<0.001)). No change was observed in urinary calcium excretion in the active group compared to the placebo group (P = 0.891). Fibroblast growth factor 23 increased significantly by 10% (P<0.018) in the active group. However, there was no difference in changes in FGF23 between treatment groups (P = 0.457).

CONCLUSION

High dose cholecalciferol significantly increases 25(OH)vitamin D and 1,25(OH)2vitamin D levels compared to placebo. No changes in urinary calcium excretion or other measured components of the mineral metabolism were found between groups.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00952562.

Dyslipidemia and kidney stone risk

PURPOSE

We studied the impact of dyslipidemia on 24-hour urinalysis and stone composition.

MATERIALS AND METHODS

We retrospectively identified patients with nephrolithiasis who underwent 24-hour urinalysis and lipid profile evaluation within 3 months. Patients were divided into groups based on total cholesterol, high density lipoprotein, nonhigh density lipoprotein and triglycerides. The groups were compared based on demographic data, diabetes, hypertension and each component of 24-hour urinalysis and stone composition. Multivariate analysis and linear regression were performed to control for potential confounders, including age, gender, body mass index, diabetes and hypertension.

RESULTS

A total of 2,442 patients with a mean age of 51.1 years were included in study. On multivariate analysis patients with high total cholesterol had significantly higher urinary potassium and calcium, those with low high density lipoprotein or high triglycerides had significantly higher urinary sodium, oxalate and uric acid with lower pH, and those with high nonhigh density lipoprotein had higher urinary sodium and uric acid. Regarding stone composition, high total cholesterol and triglycerides were significantly associated with a higher uric acid stone rate (p = 0.006 and <0.001, respectively). Linear regression showed a significant association of nonhigh density lipoprotein with higher urinary sodium (p = 0.011) and uric acid (p <0.001) as well as triglycerides and higher uric acid (p = 0.017), and lower urinary pH (p = 0.005).

CONCLUSIONS

There is a link between dyslipidemia and kidney stone risk that is independent of other components of metabolic syndrome such as diabetes and obesity. Specific alterations in the patient lipid profiles may portend unique aberrations in urine physicochemistry and stone risk.