Kidney stones and subclinical atherosclerosis in young adults: the CARDIA study

Arterial stiffness and cardiovascular risk in patients with nephrolithiasis: a 10-year prospective study

BACKGROUND

Nephrolithiasis is frequently associated with cardiovascular diseases. These conditions present common risk factors: systemic inflammation that promotes oxidative stress leading to arterial wall stiffening may also play a role in plaque formation predisposing to nephrolithiasis.

OBJECTIVES

The aim of this study was to evaluate arterial stiffness indices at baseline and after a 10-year follow-up, in patients with nephrolithiasis compared with patients without.

METHODS

A total of 82 patients (37 men; mean age 45 ± 13 years) were enrolled at the Geriatrics and Nephrology Outpatient Clinic: 66 were diagnosed with nephrolithiasis, whereas the control group consisted of 16 individuals. At baseline and after 10 years, they underwent clinical evaluation and arterial stiffness measurement, such as carotid-femoral pulse wave velocity (CF-PWV), by arterial applanation tonometry.

RESULTS

At baseline, when compared with the control group, patients with nephrolithiasis showed higher SBP and CF-PWV. After 10 years, patients with nephrolithiasis, but not those without, showed a significant raise in CF-PWV, even after adjustment for age and sex. In a stepwise regression model, with CF-PWV changes during the follow-up as the dependent variable, and age, sex, follow-up years, Δ mean arterial pressure, BMI, hypertension and nephrolithiasis as independent variables, nephrolithiasis was proved to be the only significant predictor of ΔCF-PWV, accounting for 6% of the variance.

CONCLUSION

Our study shows higher baseline CF-PWV and greater increase in ΔCF-PWV within 10 years in individuals with nephrolithiasis than in those without, demonstrating an increased cardiovascular risk for nephrolithiasis patients.

The Yield of Genetic Testing in Management of Nephrolithiasis

OBJECTIVE

To describe the yield and indications for performing genetic testing in patients with nephrolithiasis. Genetic testing for nephrolithiasis is becoming more accessible and rapid due to technologic advances. This study aimed to determine the diagnostic yield of genetic testing in a cohort of high-risk stone formers and to identify 24-hour urine characteristics to prompt genetic screening.

MATERIALS AND METHODS

We retrospectively identified patients who underwent genetic testing for nephrolithiasis from 2020 to 22 at a single institution using a custom PerkinElmer genomics panel for nephrolithiasis. We compared characteristics of patients with and without genetic abnormalities. We used receiver operator characteristic (ROC) analysis to identify candidate thresholds for genetic testing.

RESULTS

Fourteen of 36 patients (39%) who underwent genetic testing had identifiable mutations. Five patients (14%) had known pathogenic mutations, including genes for primary hyperoxaluria (PH2 and PH3), cystinuria, and enamel-renal syndrome. The remaining mutations were variants of uncertain significance. Of the 14 patients with identified mutations, only 6 had concordant 24-hour urine abnormalities, including 3/5 with known pathogenic mutations. In patients with urine oxalate ≥ 40 mg/day, 3/29 (10.3%) had PH2 or PH3. ROC analysis showed that an oxalate threshold of ≥ 80 mg/day may have promising screening characteristics.

CONCLUSION

Genetic testing for nephrolithiasis remains controversial due to unknown yield and the time and energy required to discuss results with patients. This preliminary report describes the yield and identifies clinical factors and a potential cut-off that may assist clinicians in deciding when genetic profiling should be pursued.

Inflammatory factors and the risk of urolithiasis: a bidirectional Mendelian randomization study

Background

Urolithiasis is a prevalent condition encountered in urology. Over the past decade, its global incidence has been on an upward trajectory; paired with a high recurrence rate, this presents considerable health and economic burdens. Although inflammatory factors are pivotal in the onset and progression of urolithiasis, their causal linkages remain elusive.

Method

Mendelian randomization (MR) is predicated upon genome-wide association studies (GWASs). It integrates bioinformatics analyses to reveal causal relationships between exposures and outcomes, rendering it an effective method with minimized bias. Drawing from a publicly accessible GWAS meta-analysis comprising 8,293 samples, we identified 41 genetic variations associated with inflammatory cytokines as instrumental variables. Outcome data on upper urinary tract stones, which included renal and ureteral stones (9,713 cases and 366,693 controls), and lower urinary tract stones, including bladder and urethral stones (1,398 cases and 366,693 controls), were derived from the FinnGen Consortium R9 dataset. By leveraging the bidirectional MR methodology, we aimed to decipher the causal interplay between inflammatory markers and urolithiasis.

Results

Our study comprehensively elucidated the association between genetic inflammatory markers and urolithiasis via bidirectional Mendelian randomization. Post-MR analysis of the 41 genetic inflammation markers revealed that elevated levels of circulating interleukin-2 (IL-2) (OR = 0.921, 95% CI = 0.848-0.999) suggest a reduced risk for renal stone disease, while heightened stem cell growth factor beta (SCGF-β) (OR = 1.150, 95% CI = 1.009-1.310) and diminished macrophage inflammatory protein 1 beta (MIP-1β) (OR = 0.863, 95% CI = 0.779-0.956) levels suggest an augmented risk for lower urinary tract stones. Furthermore, renal stone disease appeared to elevate IL-2 (β = 0.145, 95% CI = 0.013-0.276) and cutaneous T cell-attracting chemokine (CTACK) (β = 0.145, 95% CI = 0.013-0.276) levels in the bloodstream, whereas lower urinary tract stones were linked to a surge in interleukin-5 (IL-5) (β = 0.142, 95% CI = 0.057-0.226), interleukin-7 (IL-7) (β = 0.108, 95% CI = 0.024-0.192), interleukin-8 (IL-8) (β = 0.127, 95% CI = 0.044-0.210), growth regulated oncogene alpha (GRO-α) (β = 0.086, 95% CI = 0.004-0.169), monokine induced by interferon-gamma (MIG) (β = 0.099, 95% CI = 0.008-0.191) and macrophage inflammatory protein 1 alpha (MIP-1α) (β = 0.126, 95% CI = 0.044-0.208) levels.

Conclusion

These discoveries intimate the instrumental role of IL-2 in the onset and progression of upper urinary tract stones. SCGF-β and MIP-1β influence the development of lower urinary tract stones. Urolithiasis also impacts the expression of cytokines such as IL-2, CTACK, IL-5, IL-7, IL-8, GRO-α, MIG, and MIP-1α. There is a pressing need for further investigation to ascertain whether these biomarkers can be harnessed to prevent or treat urolithiasis.

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

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

Intensity-Specific Physical Activity Measured by Accelerometer, Genetic Susceptibility, and the Risk of Kidney Stone Disease: Results From the UK Biobank

RATIONALE & OBJECTIVE

Kidney stone disease (KSD), a significant health care problem within both developed and developing countries, has been associated with genetic risk factors. An association between physical activity and KSD risk also has been hypothesized, but studies have yielded inconsistent findings. This study investigated the association between the intensity of physical activity and the incidence of KSD accounting for genetic risk.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

A total of 80,473 participants from the UK Biobank Study.

EXPOSURE

Physical activity levels, including total physical activity (TPA), moderate-to-vigorous intensity physical activity (MVPA), and light-intensity physical activity (LPA), were measured using accelerometers and quantified using a machine learning model. A polygenic risk score (PRS) for KSD was also constructed.

OUTCOME

Individuals with KSD were identified using the International Classification of Diseases, Tenth Revision (ICD-10), and procedure codes for KSD surgery.

ANALYTICAL APPROACH

A Fine and Gray survival model was used to estimate the associations of incident KSD with TPA, MVPA, LPA, and PRS (as categorical variables). Restricted cubic splines were used to examine potential nonlinear associations within the fully adjusted models.

RESULTS

During an average follow-up of 6.19 years, 421 participants developed KSD. Participants in the highest quartiles of TPA, MVPA, and LPA had lower adjusted rates of KSD compared with those in the lowest quartiles: HR, 0.50 (95% CI, 0.44-0.56), 0.57 (95% CI, 0.51-0.64), and 0.66 (95% CI, 0.59-0.74), respectively. TPA, MVPA, and LPA were associated with a lower risk of KSD in participants with low and high genetic predisposition for KSD.

LIMITATIONS

Selection bias as participants who provided accelerometry data may have been more adherent to health care.

CONCLUSIONS

Physical activity was negatively associated with the risk of KSD, regardless of the genetic risk. Future large studies are warranted to confirm and explain the mechanisms underlying these associations.

PLAIN-LANGUAGE SUMMARY

The association between the intensity of physical activity (PA) and the incidence of kidney stone disease (KSD) after accounting for genetic risk is unclear. We conducted a comprehensive prospective cohort study utilizing participants from the UK Biobank to assess the intensity of PA using accelerometers. Our study findings indicated that greater total PA, moderate-to-vigorous-intensity PA, and light-intensity PA were each associated with a lower risk of KSD irrespective of an individual's genetic risk. Our study informs the understanding of risk factors for KSD.

Vascular calcification on the risk of kidney stone: a meta-analysis

BACKGROUND

The association between vascular calcification (VC) and kidney stone is still inconclusive. Therefore, we conducted a meta-analysis to estimate the risk of kidney stone disease in subjects with VC.

METHODS

To identify publications from related clinical studies, we performed a search on PubMed, Web of Science, Embase, and Cochrane Library databases from their inceptions until 1 September 2022. According to obvious heterogeneity, a random-effects model was used to calculate the odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Subgroup analysis was conducted trying to dissect the effects of VC in different segments and population regions in predicting kidney stone risk.

RESULTS

Seven articles were included with a total number of 69,135 patients, of which 10,052 have vascular calcifications and 4728 have kidney stones. There was a significantly higher risk of kidney stone disease in participants with VC versus control (OR = 1.54, 95% CI: 1.13-2.10). Sensitivity analysis confirmed the stability of the results. VC can be separated into abdominal, coronary, carotid, and splenic aortic calcification while pooled analysis of abdominal aorta calcification did not indicate a significant higher kidney stone risk. An obvious higher risk of kidney stone was observed in Asian VC patients (OR = 1.68, 95% CI: 1.07-2.61).

CONCLUSION

Combined evidence of observational studies suggested patients with VC may be associated with an increased risk of kidney stone disease. Despite the predictive value was relatively low, it is still worth noting that patients with VC are under the threat of kidney stone disease.

Oxalate (dys)Metabolism: Person-to-Person Variability, Kidney and Cardiometabolic Toxicity

Oxalate is a metabolic end-product whose systemic concentrations are highly variable among individuals. Genetic (primary hyperoxaluria) and non-genetic (e.g., diet, microbiota, renal and metabolic disease) reasons underlie elevated plasma concentrations and tissue accumulation of oxalate, which is toxic to the body. A classic example is the triad of primary hyperoxaluria, nephrolithiasis, and kidney injury. Lessons learned from this example suggest further investigation of other putative factors associated with oxalate dysmetabolism, namely the identification of precursors (glyoxylate, aromatic amino acids, glyoxal and vitamin C), the regulation of the endogenous pathways that produce oxalate, or the microbiota's contribution to oxalate systemic availability. The association between secondary nephrolithiasis and cardiovascular and metabolic diseases (hypertension, type 2 diabetes, and obesity) inspired the authors to perform this comprehensive review about oxalate dysmetabolism and its relation to cardiometabolic toxicity. This perspective may offer something substantial that helps advance understanding of effective management and draws attention to the novel class of treatments available in clinical practice.

Safety and Effectiveness of Evolocumab During Acute and Sub-acute Phases of Acute Coronary Syndrome (ACS): A Systematic Review and Meta-analysis

BACKGROUND

Coronary artery disease (CAD), manifested mainly as acute coronary syndrome (ACS), continues to be a major cause of mortality globally and a significant contributing factor to the global disease burden. Elevation of low-density lipoprotein cholesterol levels attributed to proprotein convertase subtilisin/Kexin type-9 (PCSK9) during and following ACS puts patients at high risk of subsequent adverse events. Evolocumab is a PCSK9 inhibitor that is associated with a significant reduction in low-density lipoprotein cholesterol (LDL-C) levels through PCSK9 inhibition in comparison to traditional statin therapy.

METHODS

We conducted a systematic review and meta-analysis of literature addressing the efficacy and safety of evolocumab compared to other lipid-lowering therapies or placebo. An extensive internet-based literature search using pre-determined key phrases supported by medical sub-headings and Boolean operators was performed in October 2022 to identify literature pertinent to the research topic. The search was primarily based on the National Library of Medicine (PubMed and Clinical Trials), MEDLINE, Cochrane, and the Science direct literature databases. Subsequently, the researchers devised PICOs-based screening criteria which had to be met by each identified study for inclusion in the review and meta-analysis. Two independent reviewers conducted data stratification and quality assessment of identified studies. Statistical analysis of the primary and secondary outcomes was conducted on the Cochrane REVMAN 5.4 statistical software for randomized trials.

RESULTS

Two thousand five hundred and seventy-six potential studies were identified for inclusion in the systematic review. Data stratification, screening, and quality assessment of these studies based on the eligibility criteria led to the exclusion of two thousand five hundred and sixty-seven studies as they did not meet the standards set. Nine randomized controlled trials progressed to numerical analysis for validity and reliability. Eight studies were included in the meta-analysis. Meta-analytical results showed a significant decrease in LDL-C changes from initiation of evolocumab therapy to 8 weeks following ACS compared to placebo. Similar results were derived in the sub-acute phase of ACS [SMD -1.95 (95% CI -2.29, -1.62)]. The meta-analysis revealed no statistically significant relationship between the risk of adverse effects, serious adverse effects, and major adverse cardiovascular events (MACE) from treatment using evolocumab in comparison to placebo [(relative risk, RR 1.04 (95% CI 0.99, 1.08) (Z = 1.53; p=0.12)].

CONCLUSION

Early evolocumab therapy initiation was associated with a significant decrease in LDL-C levels and was not associated with an increased risk of adverse effects in comparison to placebo.

A case-based review of dietary management of calcium oxalate stones

PURPOSE

The purpose of this paper is to help patients with calcium oxalate stones to access prevention and treatment options with dietary management.

METHODS

Typical cases in our hospital and other hospitals were selected for case review; combined with literature review through PubMed search, comprehensive analysis and suggestions were put forward.

RESULTS

By retrieving the literature with sufficient evidence, selecting, and summarizing, analysis of dietary liquid, oxalate and oxalate precursors, calcium, protein, fruits and vegetables, salt, high dietary fiber, and other content with high evidence index was carried out, respectively.

CONCLUSION

Through the retrospective analysis of typical cases and literature review, the importance of diet management in the prevention and treatment of calcium oxalate stones was emphasized again, and suggestions were put forward to promote the prevention and treatment of calcium oxalate stones.

Epidemiology of Kidney Stones

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

Risks of Carotid Artery Stenosis and Atherosclerotic Cardiovascular Disease in Patients with Calcium Kidney Stone: Assessment of Systemic Inflammatory Biomarkers

(1) Background: To assess the clinical significance of preoperative inflammatory biomarkers combined with atherosclerotic cardiovascular disease (ASCVD) risk score to evaluate carotid artery stenosis in patients with calcium kidney stones; (2) Methods: We conducted a prospective observational case-control study, enrolling 74 patients with calcium kidney stones and 66 age- and sex-matched healthy controls. We calculated the inflammatory biomarkers including the neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), and systemic inflammation response index (SIRI). An ultrasound of the carotid arteries was performed on all participants to identify the severity of the stenosis; (3) Results: All inflammatory biomarkers and the severity of carotid artery stenosis were higher in the calcium kidney stone group than in controls. After stratification of ASCVD, inflammatory biomarkers and carotid artery stenosis severity were still significantly higher in the calcium kidney stone group. Multivariate analyses showed that calcium kidney stones significantly increased the risk of ASCVD and carotid artery stenosis. In multivariate linear logistic regression analyses, calcium kidney stone and ASCVD score had a significant association with carotid artery occlusion, but SIRI did not; (4) Conclusions: Calcium kidney stone is associated with higher levels of inflammatory biomarkers and carotid artery stenosis. Calcium kidney stone is associated with higher levels of inflammatory biomarkers and carotid artery stenosis.

The Association between Aortic Calcification Index and Urinary Stones: A Cross-Sectional Study

Background: It is believed that vascular calcification and urinary stones may possibly have a shared mechanism. However, the association between vascular calcification and urinary stones is largely unexplored. Using the aortic calcification index (ACI) as a clinical indicator of vascular calcification, the present study aimed to examine the association between the ACI and urinary stones. Methods: This cross-sectional study included 282 patients hospitalized for either urinary stones or other urological diseases from January 2020 to December 2021 at the Department of Urology and Lithotripsy in Peking University People’s Hospital. Among them, 137 and 145 patients were divided into the stone group and the non-stone group. Multivariable logistic regression analysis was performed to examine the association between the ACI and urinary stones. The restricted cubic splines model was used to further explore the dose−response relationship between the ACI and urinary stones. Results: The median (Q1−Q3) age of the study population was 59.0 (47.0−67.0) years. After adjusting coronary heart disease, triglycerides, glucose, serum creatinine, uric acid, urea, calcium, and eGFR, the ACI was independently associated with urinary stones (odds ratio [OR], 1.07; 95% confidence interval [CI], 1.03−1.11) in a linear dose−response pattern (p for non-linearity =0.153). Age was found to interact with the effect of the ACI on urinary stones (p for interaction <0.001). Conclusions: This study found that the ACI was independently associated with urinary stones in a linear dose−response manner. Our results indicate that the ACI might be a helpful indicator for identifying populations at risk for urinary stones.

Nephrolithiasis: A Red Flag for Cardiovascular Risk

Epidemiological evidence shows that nephrolithiasis is associated with cardiovascular (CV) morbidities. The association between nephrolithiasis and CV disease is not surprising because both diseases share conditions that facilitate their development. Metabolic conditions, encompassed in the definition of metabolic syndrome (MS), and habits that promote nephrolithiasis by altering urine composition also promote clinical manifestations of CV disease. By inducing oxidative stress, these conditions cause endothelial dysfunction and increased arterial stiffness, which are both well-known predictors of CV disease. Furthermore, the subtle systemic metabolic acidosis observed in stone formers with CV disease may have a pathogenic role by increasing bone turnover and leading to reduced mineral content and osteoporosis/osteopenia. Heart valves and/or coronary artery and aortic calcifications are frequently associated with reduced mineral density. This is known as the 'calcification paradox' in osteoporosis and has also been observed in subjects with calcium nephrolithiasis. Evidence supports the hypothesis that osteoporosis/osteopenia is an independent risk factor for the development of CV calcifications. In the long term, episodes of renal stones may occur from the onset of metabolic derangements/MS to arterial stiffness/atherosclerosis and CV morbidities. These episodes should be considered a warning sign of an ongoing and silent atherosclerotic process. The evaluation of cardiometabolic risk factors and MS components should be routine in the assessment of renal stone formers. This would allow for treatment and prevention of the development of CV complications, which are much more severe for the patient and for public health.

Vascular Calcification Is Associated with Fetuin-A and Cortical Bone Porosity in Stone Formers

Background: Nephrolithiasis has been associated with bone loss and vascular calcification (VC), reflecting abnormal extraosseous calcium deposition. Fetuin-A (Fet-A) acts as a potent inhibitor of ectopic mineralization. The aim of the present study was to evaluate the prevalence of VC in stone formers (SF) and non-stone formers (NSF) and to investigate potential determinants of VC among SF, including circulating levels of Fet-A and bone microarchitecture parameters. Methods: Abdominal aortic calcification (AAC) was assessed using available computed tomography in SF and in age-, sex-, and BMI-matched NSF (potential living kidney donors). Serum Fet-A was measured in stored blood samples from SF. Bone microarchitecture parameters were obtained as a post hoc analysis of a cross-sectional cohort from young SF evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Results: A total of 62 SF (38.0 [28.0−45.3] years old) and 80 NSF (40.0 [37.0−45.8] years old) were included. There was no significant difference in AAC scores between SF and NSF. However, when dividing SF according to mean AAC score, below <5.8% (n = 33) or above ≥5.8% (n = 29), SF with higher AAC presented significantly higher BMI and tibial cortical porosity (Ct.Po) and significantly lower serum HDL, klotho, Fet-A, and eGFR. Urinary calcium did not differ between groups, but fractional excretion of phosphate was higher in the former. Upon multivariate regression, BMI, serum Fet-A, and tibial Ct.Po remained independently associated with AAC. Conclusions: This study suggests an association between reduced circulating Fet-A levels and increased bone Ct.Po with VC in SF.

The genetics of kidney stone disease and nephrocalcinosis

Kidney stones (also known as urinary stones or nephrolithiasis) are highly prevalent, affecting approximately 10% of adults worldwide, and the incidence of stone disease is increasing. Kidney stone formation results from an imbalance of inhibitors and promoters of crystallization, and calcium-containing calculi account for over 80% of stones. In most patients, the underlying aetiology is thought to be multifactorial, with environmental, dietary, hormonal and genetic components. The advent of high-throughput sequencing techniques has enabled a monogenic cause of kidney stones to be identified in up to 30% of children and 10% of adults who form stones, with ~35 different genes implicated. In addition, genome-wide association studies have implicated a series of genes involved in renal tubular handling of lithogenic substrates and of inhibitors of crystallization in stone disease in the general population. Such findings will likely lead to the identification of additional treatment targets involving underlying enzymatic or protein defects, including but not limited to those that alter urinary biochemistry.

Kidney stone disease and cardiovascular events: a study on bidirectional causality based on mendelian randomization

Background

Kidney stone disease (KSD) has been reported to be associated with several cardiovascular diseases. However, the causality between the conditions remains unknown. In the study, we performed a study on bidirectional causality by two-sample Mendelian randomization (MR) to investigate the causality between KSD and cardiovascular diseases including coronary atherosclerosis, hypertension, and cardiomyopathy.

Methods

In the recent study, we performed a bidirectional two-sample MR study using available genome-wide association summary data from the online database MRBASE. We identified genetic variants associated with KSD in one European population from UK Biobank (version 2, n=462,933). Two phenotypes of samples were chosen from the population to define our genetic instrumental variables: (I) samples with the phenotype of kidney stone/ureter stone/bladder stone (ukb-b-8297), and (II) samples with the phenotype of kidney stone surgery/lithotripsy (ukb-b-13537). For cardiovascular diseases, we picked up another independent European population from FinnGen Biobank (n=93,421). We selected the exposure and outcome SNPs and then performed the two-sample MR using R package.

Results

After bidirectional causality by two-sample MR, we verified that genetic predisposition to KSD could increase the risk of coronary atherosclerosis (OR: 4.45×1037; SE=±7.80×10¹⁴, P for MR-Egger =0.024) and cardiomyopathy (OR: 5.35×10¹³; SE=±7.18×10⁶, P for IVW=0.045 for finn-a-I9_CARDMYO, and OR: 3.60×10²⁵; SE=±3.26×10¹², P for IVW=0.041 for finn-a-I9_CARDMYOOTH) when we used ukb-b-13537 as exposure group. Furthermore, hypertension could increase the risk of KSD (OR: 1.001; SE=±1.00, P for IVW=0.003) when we used ukb-b-8297 as exposure group, without detected pleiotropy bias (P>0.05).

Conclusions

We confirmed KSD may trigger causal pathological processes including coronary atherosclerosis and cardiomyopathy. Furthermore, hypertension may causally affect KSD.

Do outcomes of ureteroscopic stone treatment vary with stone composition? A prospective analysis

Introduction

Urinary tract calculi are commonly treated with ureteroscopy and laser stone fragmentation (URSL). The composition of calculi depends on underlying patient factors. Stones associated with metabolic or infectious conditions are sometimes thought to be more difficult to treat. This analysis explores whether the composition of calculi impacts on stone-free and complication rates.

Material and methods

A prospectively maintained database of patients undergoing URSL between 2012-2021 was used to explore records for patients with uric acid (Group A), infection (Group B) and calcium oxalate monohydrate (Group C) calculi. Patients who had undergone URSL to treat ureteric or renal calculi were included. Patient demographics, stone parameters and operative details were collected, with the principal outcomes being stone-free rate (SFR) and associated complications.

Results

A total of 352 patients were included (58 Group A, 71 Group B and 223 Group C patients) and had their data analysed. SFR was >90% for all three groups and a single Clavien-Dindo grade III complication was noted. No significant differences were found between the groups for complications, SFR and day case rates.

Conclusions

This cohort of patients demonstrated that outcomes were similar for three different types of urinary tract calculi, which form for differing reasons. URSL appears to be an effective, safe treatment for all stone types with comparable results.

Understanding the link between kidney stones and cancers of the upper urinary tract and bladder

Kidney stones are one of the most common renal pathologies. While emerging evidence has implicated a potential association between kidney stones and upper urinary tract cancers (including renal cancer), there is limited understanding as to the common underlying biological pathways functionally linking the etiology of kidney stone formation and the incidence, development, and progression of urinary tract cancers. From a clinical perspective, kidney stone disease can be a barrier to oncologic care due to renal obstruction. From the epidemiological perspective, risk factors associated with both conditions include smoking, alcohol consumption, diet, and gender. Herein, we review the association between renal calculi and malignancy of the upper urinary tract and discuss the current understanding of (a) potential shared mechanisms, and (b) the impact this has on shared therapeutic management of both conditions.

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.

Urinary metabolic profile and stone composition in kidney stone formers with and without heart disease

Objective

Kidney stone disease seems to be associated with an increased risk of incident cardiovascular outcomes; the aim of this study is to identify differences in 24-h urine excretory profiles and stone composition among stone formers with and without cardiovascular disease (CVD).

Methods

Data from patients attending the Department of Renal Medicine’s metabolic stone clinic from 1995 to 2012 were reviewed. The sample was divided according to the presence or absence of CVD (myocardial infarction, angina, coronary revascularization, or surgery for calcified heart valves). Univariable and multivariable regression models, adjusted for age, sex, BMI, hypertension, diabetes, eGFR, plasma bicarbonate and potential renal acid load of foods were used to investigate differences across groups.

Results

1826 patients had available data for 24-h urine analysis. Among these, 108 (5.9%) had a history of CVD. Those with CVD were older, have higher prevalence of hypertension and diabetes and lower eGFR. Univariable analysis showed that patients with CVD had significantly lower 24-h urinary excretions for citrate (2.4 vs 2.6 mmol/24 h, p = 0.04), magnesium (3.9 vs 4.2 mmol/24 h, p = 0.03) and urinary pH (6.1 vs 6.2, p = 0.02). After adjustment for confounders, differences in urinary citrate and magnesium excretions remained significant. No differences in the probability of stone formation or stone compositions were found.

Conclusions

Stone formers with CVD have lower renal alkali excretion, possibly suggesting higher acid retention in stone formers with cardiovascular comorbidities. Randomized clinical trials including medications and a controlled diet design are needed to confirm the results presented here.

Graphic abstract

The Activation of ROS/NF-κB/MMP-9 Pathway Promotes Calcium-Induced Kidney Crystal Deposition

Idiopathic hypercalciuria is an important risk factor for the formation of calcium-containing kidney stones. Matrix metalloproteinase-9 (MMP-9) is closely related to cell and tissue remodeling and is involved in ectopic tissue calcification. However, little is known about its role in kidney stone formation. In this study, we found that the expression of MMP-9 and that of osteoblastic-related proteins was increased in normal rat kidney epithelial-like (NRK-52E) cells following treatment with a high concentration of calcium, while the knockout or overexpression of MMP-9 could, respectively, significantly inhibit or upregulate the expression of osteoblastic-related proteins and calcium crystal deposition. In addition, apoptosis and calcium crystal deposition were significantly reduced in Sprague-Dawley rats with 1,25(OH)₂D₃-induced hypercalciuria following MMP-9 inhibitor I treatment. Furthermore, inhibiting reactive oxygen species (ROS) production or the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) pathway significantly reduced calcium-induced MMP-9 expression and calcium crystal deposition. In summary, our results suggested that a high calcium concentration promotes epithelial-osteoblastic transformation and calcium crystal deposition in renal tubule cells by regulating the ROS/NF-κB/MMP-9 axis and identified a novel role for MMP-9 in regulating calcium-induced calcium crystal deposition in renal tubules.

Randall's plaque and calcium oxalate stone formation: role for immunity and inflammation

Idiopathic calcium oxalate (CaOx) stones often develop attached to Randall's plaque present on kidney papillary surfaces. Similar to the plaques formed during vascular calcification, Randall's plaques consist of calcium phosphate crystals mixed with an organic matrix that is rich in proteins, such as inter-α-trypsin inhibitor, as well as lipids, and includes membrane-bound vesicles or exosomes, collagen fibres and other components of the extracellular matrix. Kidney tissue surrounding Randall's plaques is associated with the presence of classically activated, pro-inflammatory macrophages (also termed M1) and downregulation of alternatively activated, anti-inflammatory macrophages (also termed M2). In animal models, crystal deposition in the kidneys has been associated with the production of reactive oxygen species, inflammasome activation and increased expression of molecules implicated in the inflammatory cascade, including osteopontin, matrix Gla protein and fetuin A (also known as α2-HS-glycoprotein). Many of these molecules, including osteopontin and matrix Gla protein, are well known inhibitors of vascular calcification. We propose that conditions of urine supersaturation promote kidney damage by inducing the production of reactive oxygen species and oxidative stress, and that the ensuing inflammatory immune response promotes Randall's plaque initiation and calcium stone formation.

The relationship between vascular calcifications and urolithiasis in a large, multiethnic patient population

Several studies have reported associations between vascular calcifications and urinary stone disease (USD). However, results have been inconsistent and the majority of studies did not report on race/ethnicity. We examined the association between vascular calcifications and USD in a large, racially/ethnically diverse patient population. We identified 672 USD cases and 672 controls (i.e., patients without a history of USD) from patients who underwent non-contrast CT imaging at Montefiore Medical Center in Bronx, New York between 2004 and 2013. Controls were matched to cases on age, sex and race/ethnicity. The non-contrast CT imaging was used to measure abdominal aortic calcification (AAC) and calculate the AAC severity score. Logistic regression models were used to examine associations of AAC presence and severity score with risks of USD and stone types. Cases and controls had similar AAC prevalence (45.2% vs. 44.8%, p = 0.87), and AAC severity score (median 10 vs. 9.3, p = 0.47). The presence of AAC (OR = 0.98, 95% CI 0.78-1.23; p = 0.86) or AAC severity score were not associated with risk of USD: ORs of 0.96, 0.87, 1.07 and 1.03 for increasing AAC quartiles (p-trend = 0.54). There were also no associations in the stratified analyses by race/ethnicity or by sex. However, when USD patients were stratified by stone type, brushite/apatite stone formers had an inverse association with the lowest quartile of AAC severity score (OR = 0.35, 95% CI 0.11-0.84, p = 0.04) in comparison to patients without AAC. Overall, we found no association between vascular calcifications and risk of urinary stone disease in this large, hospital-based, case-control study.

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.

Association between kidney stones and risk of developing stroke: a meta-analysis

Background

Many studies have described the relationship between kidney stones and stroke, but the results are controversial, so we conducted this meta-analysis to estimate the relationship between kidney stones and the risk of developing stroke.

Methods

Studies were marked with a comprehensive search of PubMed, EMBASE, Google, and ISI Web of Science databases through 25 March 2020. Hazard ratios (HRs) and 95% confidence intervals (CIs) were extracted, and a random-effects model or fix-effects model was used to compute the pooled combined risk estimate. Heterogeneity was reported as I². We performed subgroup and sensitivity analysis to assess potential sources of heterogeneity.

Results

Eight studies of seven articles involving 3,526,808 participants were included in the meta-analysis. Overall, kidney stones were associated with a moderate risk of stroke incidence (HR, 1.24; 95% CI, 1.11–1.40; I²=79.6%; p=0.000). We conducted a sensitivity analysis by removing the studies that had a high risk of bias. Heterogeneity subsequently decreased significantly, while an increased risk of stroke in patient with kidney stones was again demonstrated (HR, 1.16; 95% CI, 1.11–1.23; I²=28.7%; p=0.000). Stratifying analysis showed that the results were more pronounced for ischemic stroke (HR, 1.14; 95% CI, 1.08–1.22; I²=15.6%; p=0.00) and the follow-up duration ≥10 years (HR, 1.18; 95% CI, 1.10–1.27; I²=31.6%; p=0.003).

Conclusions

Our meta-analysis suggests that patients with kidney stones may have a modestly increased risk of developing stroke, especially in ischemic stroke. More large-scaled and clinical trials should be done to identify the relative impact of kidney stones on stroke outcomes in the future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-021-05113-5.

Association between metabolic syndrome components and the risk of developing nephrolithiasis: A systematic review and bayesian meta-analysis

Background: There is increasing evidence that nephrolithiasis is a systemic disease, as opposed to an isolated urinary metabolic problem, after considerable links were found between nephrolithiasis and systemic diseases such as hypertension, obesity, dyslipidemia, and insulin resistance. The interplay between these four factors defines metabolic syndrome (MetS). In this review we aim to clarify the associations of MetS and its components to kidney stone incident. Methods: Online databases of EMBASE, MEDLINE, and Google Scholar were searched from January 1998 up to October 2020 to identify observational studies examining the association between metabolic syndrome components and kidney stone incident. Bayesian random-effects meta-analysis and meta-regression were performed to observe the association. Linear dose-response analysis was conducted to shape the direction of the association. Data analysis was performed using STATA, and R statistics. Results: A total of 25 potentially relevant studies (n = 934,588 participants) were eventually identified. The pooled results suggested that metabolic syndrome was associated with an increased risk of nephrolithiasis with an odds ratio (OR) of 1.769 (95% CI: 1.386 - 2.309).  The summary OR of hypertension and dyslipidemia for developing nephrolithiasis were 1.613 (95% CI: 1.213 - 2.169) and 1.586 (95% CI: 1.007 - 2.502) respectively. The presence of diabetes mellitus and obesity had an OR of 1.552 (95% CI: 1.027 - 2.344) and 1.531 (95% CI: 1.099 - 2.109) respectively. Our results revealed that the increasing number of MetS traits will increase the risk of developing nephrolithiasis, the higher the fasting plasma glucose, and body mass index, the higher the risk of kidney stones incident. Conclusions: Our results suggest that hypertension, diabetes, obesity and dyslipidemia are associated with increased risk of developing nephrolithiasis. Linear significant association between MetS components and nephrolithiasis were revealed in our study which reinforced the notion that should be considered a systemic disorder.

Urolithiasis, Independent of Uric Acid, Increased Risk of Coronary Artery and Carotid Atherosclerosis: A Meta-Analysis of Observational Studies

Background and Aims

Recent epidemiological evidence indicates an association between urolithiasis and atherosclerosis; however, results are incongruous. Our aim is to summarize the association between urolithiasis and arteriosclerosis risk through a detailed meta-analysis.

Methods

Relevant studies published before April 2019 were identified by searching OVID, EMBASE, PubMed, Web of Science database, and Cochrane Library. The relationship between urolithiasis and the risk of atherosclerosis was assessed by using odds ratio (OR) values and the corresponding 95% confidence intervals (CIs), and the selection of fixed- or random-effects model based on heterogeneity.

Results

The meta-analysis includes 8 observational studies that contained 70,716 samples. Pooled results showed that urolithiasis was associated with an increased adjusted and unadjusted risk estimated for atherosclerosis (P=0.017 and P=0.017 and n = 65,751/70,716) with serum uric acid levels less than 6.0 mg/dl, it still showed that urolithiasis was associated with a higher risk of atherosclerosis (P=0.017 and I² = 0.0%, P=0.017 and P=0.017 and P=0.017 and

Conclusions

Urolithiasis is associated with an increased risk for atherosclerosis, especially in coronary artery and carotid atherosclerosis. Urolithiasis may be another potential risk factor of atherosclerosis, which is independent of serum uric acid levels.

Effect of endothelial dysfunction on the pathogenesis of urolithiasis in patients with metabolic syndrome

OBJECTIVE

The aim of the present prospective clinical study was to investigate the possible effect of endothelial dysfunction in urolithiasis.

METHODS

The study included 92 patients older than 18 years. The patients were divided into 4 groups with 23 patients each as group 1: metabolic sydrome (MetS) (-) stone disease (SD) (-), group 2: MetS (-) SD (+), group 3: MetS (+) SD (-) and group 4: MetS (+) SD (+). C-reactive protein, homocysteine, uric acid, and creatinine levels were evaluated between the groups. Endothelial (dys)function was evaluated based on the brachial artery flow-mediated dilation (FMD) measurement.

RESULTS

The mean age was 41.9 ± 10.2 (range, 18-62) years. Mean FMD value was 15.9 ± 18.2% (range, 24.0-68.5%). A strong significant difference was found between group 1 and 2 (p < .001); group 1 and 3 (p < .001) and group 1 and 4 (p < .001) with regard to FMD.

CONCLUSION

These results suggest that endothelial dysfunction plays an important role in the pathogenesis of urolithiasis in patients with MetS.

Ectopic biomineralization in kidney stone formers compared to non-stone formers

Background

Kidney stone formers (SFs) are at increased risk of stroke, myocardial infarction, and atherosclerosis of the carotid and coronary arteries. These cardiovascular and urologic pathologies can result from ectopic biomineral deposition. The objectives of this study are: (I) to evaluate risk factors for ectopic biomineralization, and (II) to characterize the overall burden of ectopic minerals in known SFs compared to non-stone formers (NSFs) matched for these risk factors.

Methods

Presence and quantity of biominerals at eight anatomic locations (abdominal aorta, common iliac arteries, pelvic veins, prostate or uterus, mesentery, pancreas, and spleen) were determined in a case control study by retrospective analysis of clinical non-contrast computed tomography scans obtained from 190 SFs and 190 gender- and age-matched NSFs (renal transplant donors). Predictors of biomineralization were determined using negative binomial regression. A subgroup of 140 SFs and 140 NSFs were matched for risk factors for systemic biomineralization, and mineralization was compared between these matched SFs and NSFs using ordinal logistic regression.

Results

Hypertension, hyperlipidemia, diabetes mellitus, and smoking were more common amongst SFs. Risk factors for increased systemic biomineralization included history of nephrolithiasis, male gender, older age, and history of hyperlipidemia. When controlling for these comorbidities, SFs had significantly increased biomineralization systemically and at the abdominal aorta, iliac arteries, prostate, mesentery, pancreas, and spleen compared to NSFs.

Conclusions

The current study provides evidence that SFs are at increased risk of biomineralization systemically, independent of common risk factors of atherosclerosis.

Calcium Kidney Stones are Associated with Increased Risk of Carotid Atherosclerosis: The Link between Urinary Stone Risks, Carotid Intima-Media Thickness, and Oxidative Stress Markers

Previous studies have suggested that kidney stone formers are associated with a higher risk of cardiovascular events. To our knowledge, there have been no previous examinations of the relationship between carotid intima-media thickness (IMT) and urinary stone risk factors. This study was aimed toward an investigation of the association between dyslipidemia, IMT, and 24-hour urinalysis in patients with calcium oxalate (CaOx) or calcium phosphate (CaP) stones. We prospectively enrolled 114 patients with kidney stones and 33 controls between January 2016 and August 2016. All patients were divided into four groups, according to the stone compositions—CaOx ≥ 50% group, CaP group, struvite group, and uric acid stones group. Carotid IMT and the carotid score (CS) were evaluated using extracranial carotid artery doppler ultrasonography. The results of a multivariate analysis indicated that a higher serum total cholesterol (TC) and low-density lipoprotein (LDL) were all associated with lower urinary citrate and higher CS in both the CaOx ≥ 50% and CaP groups. Higher serum TC and LDL were also associated with increased serum 8-OHdG levels in both groups. The levels of carotid IMT and CS in the CaOx ≥ 50% and CaP groups were all significantly higher than in the controls. These findings suggest a strong link between dyslipidemia, carotid atherosclerosis, and calcium kidney stone disease.

Educational review: role of the pediatric nephrologists in the work-up and management of kidney stones

BACKGROUND

The incidence of nephrolithiasis in children and adolescents is increasing and appears to double every 10 years. The most important role of the pediatric nephrologist is to diagnose and modify various metabolic and non-metabolic risk factors, as well as prevent long-term complications especially in the case of recurrent nephrolithiasis.

OBJECTIVE

The purpose of this review is to summarize the existing literature on the etiology and management of pediatric nephrolithiasis.

RESULTS

The incidence of kidney stones is increasing; dietary and environmental factors are probably the main causes for this increased incidence. In most pediatric patients, the etiology for the kidney stones can be identified. Metabolic factors, such as hypercalciuria and hypocitraturia, urinary tract infection, and urinary stasis, constitute leading causes. Herein, we review the etiologies, diagnostic work-up, and treatment options for the most prevalent causes of kidney stones. The detrimental effects of excessive dietary sodium, reduced fluid intake, and the benefits of plant-based over animal-based protein consumption on urinary crystal formation are discussed. We also review the long-term complications.

CONCLUSIONS

Pediatric nephrologists have an important role in the diagnostic work-up and prevention of recurring nephrolithiasis.

Oxalates, urinary stones and risk of cardiovascular diseases

Increased level of oxalates in urine and plasma can be attributed to endogenous overproduction, increased ingestion or excessive intestinal absorption. When a supersaturation status is reached, oxalates combine with calcium and crystallize to form 80% of the urinary stones. Several cardiovascular diseases such as coronary heart disease and stroke are thought to be associated with the formation of urinary stones via sharing the same pathogenesis and/or risk factors. This review investigated the evidence linking oxalates/urinary stones to cardiovascular diseases. Eventually, two theories can explain the possible association between urinary stones and cardiovascular diseases: the theory of common origin and the theory of common risk factors. While the first theory is based on the common vascular pathophysiology of urinary stones and cardiac events, the later suggests that metabolic syndrome traits increase the risk of urinary stones and cardiovascular diseases independently. A few cohort studies showed a higher risk of coronary heart disease and stroke among people with history of urinary stones than people without it while other cohort studies did not. These studies had different definitions for cardiovascular diseases, used various methods to assess urinary stones, and some of them did not control for potential confounders. When they were pooled together in meta-analyses, a significant heterogeneity across studies was observed. In conclusion, although there is some evidence indicating that urinary stones could increase the risk of cardiovascular diseases, a substantial causal relationship cannot be settled.

Pseudoxanthoma Elasticum, Kidney Stones and Pyrophosphate: From a Rare Disease to Urolithiasis and Vascular Calcifications

Pseudoxanthoma elasticum is a rare disease mainly due to ABCC6 gene mutations and characterized by ectopic biomineralization and fragmentation of elastic fibers resulting in skin, cardiovascular and retinal calcifications. It has been recently described that pyrophosphate (a calcification inhibitor) deficiency could be the main cause of ectopic calcifications in this disease and in other genetic disorders associated to mutations of ENPP1 or CD73. Patients affected by Pseudoxanthoma Elasticum seem also prone to develop kidney stones originating from papillary calcifications named Randall’s plaque, and to a lesser extent may be affected by nephrocalcinosis. In this narrative review, we summarize some recent discoveries relative to the pathophysiology of this mendelian disease responsible for both cardiovascular and renal papillary calcifications, and we discuss the potential implications of pyrophosphate deficiency as a promoter of vascular calcifications in kidney stone formers and in patients affected by chronic kidney disease.

Nonrenal Systemic Arterial Calcification Predicts the Formation of Kidney Stones

Background: Recent data indicate that kidney stone formers (KSFs) may have increased biomineralization at anatomic sites throughout the body compared with nonstone formers (NSFs). The objective of this study is to compare the volume of nonrenal systemic calcifications between KSF and NSF by using a standardized system to analyze calcifications in the abdominal aorta (AA) and splenic artery (SA). Methods: The NSF cohort was obtained from a kidney donor's prospectively maintained database. One hundred ninety-seven NSF were matched to 197 KSF based on age, gender, and body mass index. Noncontrast CT scans were evaluated and semiautomated CT software was utilized to provide an AA and SA calcification Agatston score. Wilcoxon rank-sum test was used on continuous variables and chi-squared test or Fisher's exact test on categorical variables. Odds ratios (ORs) were given for a variable's influence on the formation of stones or calcifications. Results: AA and SA calcifications were more prevalent in the KSF group (p = 0.011 and p = 0.027, respectively). KSFs were 1.9 times more likely to have intermediate or severe AA calcification than NSFs (OR = 1.9, p = 0.004). Severe AA calcifications had even a greater association (OR = 3.1, p = 0.019). KSFs were also more likely to have SA, but this did not reach statistical significance (OR = 3.7, p = 0.103). Conclusion: Patients with increased systemic calcifications, specifically aortic or splenic calcifications, may be at an increased risk for future kidney stone formation. Patients with these imaging findings and additional risk factors for stone disease may be counseled on the future risk of stones.

Which Diet for Calcium Stone Patients: A Real-World Approach to Preventive Care

Kidney stone disease should be viewed as a systemic disorder, associated with or predictive of hypertension, insulin resistance, chronic kidney disease and cardiovascular damage. Dietary and lifestyle changes represent an important strategy for the prevention of kidney stone recurrences and cardiovascular damage. A full screening of risk factors for kidney stones and for cardiovascular damage should be recommended in all cases of calcium kidney stone disease, yet it is rarely performed outside of stone specialist clinics. Many patients have a history of kidney stone disease while lacking a satisfactory metabolic profile. Nonetheless, in a real-world clinical practice a rational management of kidney stone patients is still possible. Different scenarios, with different types of dietary approaches based on diagnosis accuracy level can be envisaged. The aim of this review is to give patient-tailored dietary suggestions whatever the level of clinical and biochemistry evaluation. This can help to deliver a useful recommendation, while avoiding excessive dietary restrictions especially when they are not based on a specific diagnosis, and therefore potentially useless or even harmful. We focused our attention on calcium stones and the different scenarios we may find in the daily clinical practice, including the case of patients who reported renal colic episodes and/or passed stones with no information on stone composition, urinary risk factors or metabolic cardiovascular risk factors; or the case of patients with partial and incomplete information; or the case of patients with full information on stone composition, urinary risk factors and metabolic cardiovascular profile.

Is oxidized low-density lipoprotein the connection between atherosclerosis, cardiovascular risk and nephrolithiasis?

Nephrolithiasis is considered a systemic disease. A link has been established between nephrolithiasis, cardiovascular disease (CVD), the metabolic syndrome and atherosclerosis. A significant correlation has been found between the high levels of oxidized low-density lipoprotein (oxLDL) and CVD and atherosclerosis, including coronary and femoral artery disease. To the best of our knowledge, oxLDL has not been evaluated in patients with nephrolithiasis. This study aimed to evaluate serum levels of oxLDL, anti-oxLDL antibodies (oxLDL-ab) and other markers of atherosclerosis in patients with nephrolithiasis, according to the severity of the disease. The population sample consisted of 94 patients of 30-70 years of age with no symptoms of CVD who presented with renal calculi documented by ultrasonography, abdominal X-ray or computed tomography. The patients were divided into two groups: Group 1 (≥ 3 stones) and Group 2 (1-2 stones). A comparison control group was formed with 21 healthy individuals. Enzyme-linked immunosorbent assays were used to assess oxLDL and oxLDL-ab. Lipid peroxidation indexes were also analyzed. Median serum oxLDL values were higher in Groups 1 and 2 compared to the control group (≥ 3 stones, p = 0.02; 1-2 stones, p = 0.03). Median serum anti-oxLDL antibody levels were lower in the patients in Group 1 compared to the controls (p = 0.03). There was no significant difference in the oxLDL/oxLDL-ab ratio between patients and controls. These findings suggest that this may be the link between nephrolithiasis and the greater incidence of atherosclerosis and cardiovascular disease in patients with kidney stones.

Urinary proteomics reveals association between pediatric nephrolithiasis and cardiovascular disease

PURPOSE

To study (1) the differences in the relative abundance of urinary proteins between children with kidney stones (RS) and hypercalciuria, hypocitraturia, normal metabolic work-up, and healthy controls (HC); (2) the association of these proteins with various diseases.

METHODS

Quantitative proteomic comparison of pooled urine from RS (N = 30, 24 females, mean age 12.95 ± 4.03 years) versus age- and gender-matched HC, using mass spectrometry. Relative protein abundance was estimated using spectral counting. Proteins of interest were selected using the following criteria: (1) ≥ 5 spectral counts; (2) ≥ twofold difference in spectral counts; and (3) ≤ 0.05 p value for the Fisher's Exact Test.

RESULTS

Of the 1813 proteins identified, 229 met the above criteria, with 162 proteins up-regulated in the RS group and 67 up-regulated in HC. The largest group of proteins (30 out of 229) was found to be associated with cardiovascular disease (CVD). Of those, 16 were involved in coagulation, fibrinolysis, and adhesion, 10 in inflammation, 5 in lipid transport and metabolism, and 4 in oxidative stress. All except two were exclusively found in children with hypercalciuria and hypocitraturia, and were not seen in children with normal metabolic work-up.

CONCLUSION

Using a proteomic approach, we found a significant association between hypercalciuric and hypocitraturic nephrolithiasis and CVD in children. The shared risk factors among both diseases are endothelial dysfunction and atherosclerosis caused by abnormal coagulation, adhesion, disturbance of lipid transport and metabolism, oxidative stress and inflammation. Further understanding of the pathophysiological link between nephrolithiasis and CVD is necessary for developing new therapeutic targets.

The influence of metabolic syndrome and its components on the development of nephrolithiasis

The prevalence of kidney stone disease is increasing, afflicting 7%–11% of the United States population. Multiple systemic conditions, including obesity and diabetes, are also on the rise. Further, the literature has demonstrated a strong association between metabolic syndrome, its components, and kidney stone disease. In this article, we aim to review the associations of metabolic syndrome and nephrolithiasis, discussing the pathophysiology, urinary parameters, and clinical presentations. With this knowledge, urologists will have a more comprehensive understanding of this complex population of metabolic stone formers enabling improved patient management and treatment of stone disease.

Risk of Nephrolithiasis in Patients With Sleep Apnea: A Population-Based Cohort Study

STUDY OBJECTIVES

To delineate the relationship between sleep apnea and subsequent risk of nephrolithiasis.

METHODS

We conducted a retrospective cohort analysis of a general population sample from Taiwan National Health Insurance Research Database (NHIRD) from January 1, 2000 to December 31, 2012. Patients with sleep apnea without prior diagnosis of nephrolithiasis (n = 7,831) were identified and subsequent development of nephrolithiasis was compared to an age- and sex-matched control group (n = 31,293) without sleep apnea. The Cox proportional hazard regression models were used to evaluate the association between sleep apnea and subsequent nephrolithiasis development.

RESULTS

After adjusting for age, sex, and comorbidities, the risk of nephrolithiasis remained significantly increased in the sleep apnea group (hazard ratio [HR] = 1.35; 95% confidence interval [CI] = 1.23-1.48; P < .001). Compared to controls, elevated HRs of nephrolithiasis were observed for male patients (HR = 1.22; 95% CI 1.09-1.36; P < .001) and those aged 20-39 years (HR = 1.28; 95% CI 1.09-1.49; P < .01) and 40-59 years (HR = 1.17, 95% CI 1.03-1.34, P < .05) in the sleep apnea cohort. Risk of nephrolithiasis in patients with sleep apnea increased significantly with concomitant metabolic-related comorbidities, gouty arthritis, and urinary tract infection.

CONCLUSIONS

Sleep apnea is associated with an increased subsequent risk of the development of nephrolithiasis. Young male patients with sleep apnea and concomitant comorbidities are at the greatest risk for nephrolithiasis formation.

Cross-talk between renal lithogenesis and atherosclerosis: an unveiled link between kidney stone formation and cardiovascular diseases

The prevalence of kidney stones and cardiovascular diseases (CVDs) are increasing throughout the world. Both diseases are chronic and characterized by accumulation of oxidized proteins and lipids in the renal tissue and arterial wall, respectively. Emerging studies have revealed a positive association between nephrolithiasis and CVDs. Based on preclinical and clinical evidences, this review discusses: (i) stone forming risk factors, crystal nucleation, aggregation, injury-induced crystal retention, and stone formation, (ii) CVD risk factors such as dyslipidemia, perturbation of gut microbiome, obesity, free radical-induced lipoprotein oxidation, and retention in the arterial wall, subsequent foam cell formation, and atherosclerosis, (iii) mechanism by which stone forming risk factors such as oxalate, calcium, uric acid, and infection contribute toward CVDs, and (iv) how CVD risk factors, such as cholesterol, phospholipids, and uric acid, contribute to kidney stone formation are described.

Inflammatory Cytokines in the Papillary Tips and Urine of Nephrolithiasis Patients

INTRODUCTION

Intrarenal inflammation has been implicated in the pathogenesis of nephrolithiasis, with prior work showing increased urine levels of IL-6, IL-8, and CCL-2 in stone patients. However, no studies have assessed for inflammation in the renal papillae. We sought to characterize novel papillary tip and urinary biomarkers in stone patients.

MATERIALS AND METHODS

Ninety-two patients with nephrolithiasis undergoing percutaneous nephrolithotomy were enrolled. Papillary tip biopsies, kidney urine, and bladder urine were collected, as well as voided urine from eight healthy volunteers. Quantitative polymerase chain reaction was performed to measure inflammatory gene expression.

RESULTS

Initial 84-gene polymerase chain reaction array revealed significant elevation of several cytokines in stone patients vs controls (fold change 2.3-694). Twenty-four genes were selected for final analysis. In 41 pairs of urine samples, levels of CCL5, CD40, FasL, RIPK2, SELE, TLR3, and IL-15 were significantly elevated in kidney vs bladder urine (p0.0001-0.04). In 23 triplets of samples, expression of these cytokines plus CCL2, CCL7, CCR2, CSF1, CXCL9, and CXCL10, was significantly greater in papillary tips vs urine samples (p0.001-0.05). Cytokine elevation was independent of maximum postoperative heart rate, respiratory rate, temperature, leukocyte count, urinary tract infection in the past year, presence or absence of antibiotics at the time of surgery, and stone composition (all p > 0.05).

CONCLUSION

Expression of CCL-2, CCL-5, CCL-7, CCR-2, CD40, CSF1, CXCL-9, CXCL-10, Fas-L, RIPK2, SELE, and TLR-3 is markedly elevated in the papillary tips, kidney urine, and bladder urine of nephrolithiasis patients. Cytokine elevation was independent of signs of systemic inflammation. These findings further support the role of inflammation in nephrolithiasis and imply that the inflammatory process likely begins at the renal papillae. These may represent novel biomarkers of stone disease, which may be useful in basic nephrolithiasis research, disease diagnosis, and prognosis.

Urolithiasis is associated with an increased risk of stroke: a population-based 5-year follow-up study

BACKGROUND

Epidemiological studies have reported an association between urolithiasis and cardiovascular disease. However, studies examining the risks of ischaemic and haemorrhagic stroke in patients with urolithiasis are limited.

AIMS AND METHODS

By using a nationwide population database, we conducted a matched cohort study to investigate the association between urolithiasis and longitudinal risks of ischaemic and haemorrhagic stroke.

RESULTS

The urolithiasis and non-urolithiasis cohorts included 12 979 and 64 895 patients respectively. Of these, 728 (5.6%) and 2802 (4.3%) patients in the urolithiasis and non-urolithiasis cohorts, respectively, had a stroke during the 5-year follow-up period. The hazard ratio (HR) for stroke was 1.19 times higher (95% confidence interval [CI] = 1.10-1.29; P < 0.001) in the urolithiasis cohort than in the non-urolithiasis cohort after adjustment for potential confounders. The risk of both ischaemic (adjusted HR = 1.16; 95% CI = 1.05-1.29) and haemorrhagic stroke (adjusted HR = 1.30; 95% CI = 1.03-1.64) remained significant in the urolithiasis cohort. Furthermore, the risk of stroke was significant in both men (adjusted HR = 1.16; 95% CI = 1.05-1.28) and women (adjusted HR = 1.26; 95% CI = 1.10-1.45). Middle-aged (40-59 years; adjusted HR = 1.26; 95% CI = 1.10-1.45) and older (≥60 years; adjusted HR = 1.14; 95% CI = 1.03-1.27) patients had a particularly high risk of stroke.

CONCLUSIONS

The present study detected an increased risk of both ischaemic and haemorrhagic stroke in patients with urolithiasis, particularly in those older than 40 years.

Predictive value of preoperative inflammatory response biomarkers for metabolic syndrome and post-PCNL systemic inflammatory response syndrome in patients with nephrolithiasis

Neutrophil to lymphocyte ratio (NLR), derived neutrophil to lymphocyte ratio (dNLR), platelet to lymphocyte ratio (PLR) and lymphocyte to monocyte ratio (LMR) were promising biomarkers used to predict diagnosis and prognosis in various inflammatory responses diseases and cancers. However, there have been no reports regarding these biomarkers in kidney stone patients. This study aimed to evaluate the predictive value of inflammatory biomarkers for metabolic syndrome (MetS) and post-PCNL SIRS in nephrolithiasis patients. We retrospectively enrolled 513 patients with nephrolithiasis and 204 healthy controls. NLR, dNLR, LMR and PLR in nephrolithiasis patients were significantly higher than control group. Patients with renal stone have higher NLR, dNLR, LMR and PLR than those without. ROC curve analysis indicated NLR, dNLR, LMR and PLR for predicting patients with nephrolithiasis and MetS, displayed AUC of 0.730, 0.717, 0.627 and 0.606. Additionally, ROC curves, using post-PCNL SIRS as the end-point for NLR, dNLR, LMR and PLR with AUC of 0.831, 0.813, 0.723 and 0.685. Multivariate analysis revealed that NLR, dNLR represented independent factors for predicting post-PCNL SIRS. While LMR independently associated with MetS. These resluts demonstrate preoperative NLR, dNLR and LMR appears to be effective predictors of post-PCNL SIRS and LMR of MetS in nephrolithiasis patients.

Vascular Disease and Kidney Stones: Abdominal Aortic Calcifications Are Associated with Low Urine pH and Hypocitraturia

OBJECTIVE

Vascular calcifications are associated with nephrolithiasis. Although studies have demonstrated correlations with vascular disease and calcium stones in kidney stone formers (KSF), an etiologic link has remained elusive. As a noncontrast CT (NCCT) scan is typically part of a stone evaluation, our objective was to evaluate the association of NCCT-based assessment of abdominal aortic calcifications (AACs) with 24-hour urine parameters and stone composition.

MATERIALS AND METHODS

Ninety-seven KSF were included with CT imaging and 24-hour urine studies. For each patient, semi-automated CT software was utilized to provide an AAC Agatston score from the celiac axis to the aortic bifurcation. Univariate analysis was performed to compare patients with or without AAC. Multivariate logistic regression was performed to assess for variables associated with 24-hour urine parameters and stone composition.

RESULTS

The presence of AAC was associated with hypertension, diabetes, peripheral vascular disease, and coronary artery disease. Patients with any AAC showed lower 24-hour urine citrate (399 vs 593 mg/day, p < 0.001) and lower 24-hour urine pH (5.862 vs 6.328, p = 0.003). When controlling for age, system comorbidities, the presence of AAC was associated with low urine pH <6 (odds ratio [OR] 2.86, p = 0.032) and hypocitraturia <320 mg/day (OR 4.37, p = 0.005). The receiver operating characteristic curve showed that increasing AAC was associated with low urine pH (area under the curve [AUC] 0.683, p = 0.002) and uric acid stone formation (AUC 0.698, p = 0.045).

CONCLUSIONS

NCCT-based diagnosis of AAC is associated with low urine pH, hypocitraturia, and uric acid stone formation. The presence of AAC could be considered an additional prognosticator for the utility of alkalinization therapy.

Renal Calcium Oxalate Deposits Induce a Pro-Atherosclerotic and Pro-Osteoporotic Response in Mice

Urinary stone disease (USD) is increasing in adult and pediatric populations. Adult and pediatric studies have demonstrated decreased bone mineral density and increased fracture rates. USD has also been independently linked to increased rates of myocardial infarction and cerebral vascular accidents. Although USD is a multisystem disorder involving the kidneys, bone, and vasculature, the molecular mechanisms linking these three organs remain unknown. Calcium oxalate nephropathy was induced in C57BL/6J mice with intra-peritoneal (ip) injection of sodium glyoxolate. Half of each kidney underwent Pizzalato staining and half was snap frozen for RNA extraction. RT² Profiler Mouse Atherosclerosis, Osteoporosis, and Calcium Signaling PCR Arrays (Qiagen) were performed. Only results that passed quality checks in PCR array reproducibility and genomic DNA contamination were included. Genes had to show at least fourfold differential expression and P < 0.01 to be considered significant. Atherosclerosis array showed upregulation of 19 genes by fourfold, 10 of which were ≥10-fold. All 19 had P ≤ 0.002. The Osteoporosis array showed fourfold upregulation of 10 genes, five showed >10-fold increase. All 10 have P ≤ 0.003. The calcium signaling array showed significant fourfold upregulation of 10 genes, four of which were ≥10-fold. All 10 have P ≤ 0.03. We have demonstrated that calcium oxalate nephropathy can induce upregulation of atherosclerotic, metabolic bone, and calcium homeostasis genes in a murine model. This may be and initial step in identifying the molecular mechanisms linking stone, bone, and cardiovascular disease. J. Cell. Biochem. 118: 2744-2751, 2017. © 2017 Wiley Periodicals, Inc.