Association of metabolic syndrome traits and severity of kidney stones: results from a nationwide survey on urolithiasis in Japan

Rising occurrence of hypocitraturia and hyperoxaluria associated with increasing prevalence of stone disease in calcium kidney stone formers

OBJECTIVE

To evaluate metabolic risk factors in calcium kidney stone formers from two different decades, comparing changes in metabolic profiles over time.

METHODS

A retrospective analysis was performed of calcium kidney stone formers who underwent metabolic evaluation of urolithiasis with 24-hour urine collections at a single institution. There were 309 patients evaluated from 1988 to 1994 (Group A), and 229 patients from 2007 to 2010 (Group B). A comparison between both groups was performed to assess changes in demographics and in metabolic stone profiles.

RESULTS

Comparing Group A to Group B, the percentage of females increased from 43 to 56%, obese patients (BMI ≥ 30) increased from 22 to 35%, and patients ≥ 50 years increased from 29 to 47% (all p < 0.005). A greater percentage of patients had hypocitraturia in the recent cohort (46-60%, p = 0.001), with hypocitraturia significantly more frequent in obese patients (p = 0.005). Hyperoxaluria was also increased in Group B compared to Group A (23-30% p = 0.07), a finding that was significant in males (32-53%, p = 0.001).

CONCLUSIONS

Urolithiasis has increased in females, obese, and older patients, consistent with population-based studies. We report a rising incidence of hypocitraturia and hyperoxaluria in the contemporary cohort, particularly in obese patients and in males, respectively. Further studies are needed to better characterize the metabolic changes corresponding to the increase in stone disease.

Metabolic Syndrome Negatively Impacts Stone-Specific Quality of Life

Purpose: Metabolic syndrome (MetS) is a cluster of metabolic diseases that is linked to atherosclerotic cardiovascular disease. MetS has also been linked to increased nephrolithiasis. However, limited research has been conducted on MetS and its impact on stone-specific health-related quality of life (HRQOL). This study aims to examine the hypothesis that the presence of MetS is associated with decreased HRQOL. Materials and Methods: The Wisconsin Stone Quality of Life Questionnaire, a stone-specific HRQOL questionnaire, was used to survey 3051 patients with kidney stones. Medical history was collected from patients. These data were used to distinguish MetS patients from non-MetS patients. Among patients with current stones, a Wilcoxon rank sum test was used to compare HRQOL scores from MetS patients and non-MetS patients. HRQOL from patients with and without individual MetS components were also compared, and a multivariate analysis was conducted. Results: Statistical comparison between MetS patients (median score 102/140) and non-MetS patients (median score 106/140) demonstrated a lower stone-specific HRQOL in patients with MetS (p = 0.049). Among individual MetS components, patients with diabetes mellitus (DM) or body mass index (BMI) >30 had significantly lower HRQOL than patients without DM or BMI <30 (p = 0.028 and p < 0.001, respectively). The multivariate analysis supported this trend as MetS remained a significant predictor of decreased HRQOL (p = 0.002) after controlling for other variables assessed. Conclusions: This study indicates an association between MetS and a lower stone-specific QOL. This has important implications for stone prevention strategies in patients with MetS. Clinical Trial Registration number: H14-01143.

Statins significantly alter urinary stone-related urine biochemistry in calcium kidney stone patients with dyslipidemia

OBJECTIVE

To investigate whether the use of statins would alter 24-h urine biochemistry in male patients with calcium kidney stones.

METHODS

We prospectively recruited 78 male patients with calcium kidney stones between May 2017 and December 2017, and 30 male controls with matching sex and age, but without kidney stones. All patients were classified into higher- and lower-risk groups of atherosclerotic cardiovascular disease according to the American College of Cardiology/American Heart Association guidelines. Atorvastatin 20 mg per day was prescribed for 12 weeks to the higher risk patients. For kidney stone group, 24-h urine collections were carried out before and after statin therapy.

RESULTS

A total of 78 patients and 30 controls were included. Higher-risk patients had significantly higher urine uric acid and calcium levels than lower-risk patients. After atorvastatin treatment for 12 weeks, urine citrate significantly increased (P < 0.001) accompanied with increased urine pH (P < 0.001), whereas urine uric acid significantly decreased after treatment. Although urine oxalate significantly increased after treatment (P = 0.037), we did not find any significant difference in urine calcium, ion activity product of calcium oxalate and ion activity product of calcium phosphate.

CONCLUSION

These findings suggest that atorvastatin administration might increase urinary citrate and decrease urinary uric acid in patients with calcium kidney stones and dyslipidemia.

Correlation of metabolic syndrome and urolithiasis: A prospective cross-sectional study

Background:

Correlation between urolithiasis and metabolic syndrome has been demonstrated in the literature. This study assessed the association of metabolic syndrome and its components with urolithiasis in Indian patients.

Methods:

A cross-sectional prospective observation study included patients aged >18 years with urolithiasis. Demographic details, body mass index (BMI), waist circumference, blood pressure, and laboratory parameters were examined.

Results:

Total 1200 patients with urolithiasis were divided into two groups (with [n = 208] and without metabolic syndrome [n = 992]). The mean age of total population was 47.26 (14.68) years with 721 males and 479 females. The mean height, weight, BMI were significantly different between both groups (P < 0.001). Proportion of obese (BMI >25) patients, proportion of patients with hyperuricemia, waist circumference, blood pressure, triglyceride, fasting blood sugar (FBS) levels were significantly higher in patients with metabolic syndrome; however, high density lipoprotein (HDL) levels were significantly reduced in metabolic syndrome group (P < 0.001). A significantly increasing trend in mean waist circumference, triglycerides, FBS, systolic blood pressure and diastolic blood pressure and a decreasing trend in mean HDL with increase in number of metabolic components were observed (P < 0.001). Female patients were 19.6 times more likely to develop metabolic syndrome than male patients (P < 0.001). Increasing waist circumference, triglycerides, FBS, blood pressure were associated with increased risk of metabolic syndrome (P < 0.05). Decreasing HDL was associated with reduced risk of metabolic syndrome. Patients with hyperuricemia were 5.68 times more likely to exhibit metabolic syndrome (P = 0.006).

Conclusion:

This study indicates the presence of a significant association of metabolic syndrome and its components with urolithiasis.

Sex Differences in Kidney Stone Disease in Chinese Patients with Type 2 Diabetes Mellitus

Objectives

To investigate the characteristics of kidney stone disease (KSD) among the Chinese population with type 2 diabetes mellitus (T2DM) and identify sex-specific factors associated with KSD.

Methods

A single-center, cross-sectional analysis was performed among Chinese patients with T2DM. KSD was identified by ultrasonography or computed tomography results. Demographic data, physical measurements, laboratory measurements, comorbidities, and related medication data were collected and analyzed. Binary logistic regression was used to explore the associated factors.

Results

A total of 7,257 patients with T2DM were included in the study, of which 56.1% were male and 15.0% were diagnosed with KSD. The male-to-female ratio for KSD among T2DM patients was 1.35. Among all the T2DM patients, male gender, HOMA2-IR, uric acid, and renal cysts were independent risk factors for KSD development, whereas serum phosphorus and the use of angiotensin-converting enzyme inhibitors (ACEIs) were independent protective factors for KSD. Among male diabetic patients, triglycerides, HOMA2-IR, renal cysts, and urinary tract infections were all associated with a greater risk of KSD. In contrast, serum phosphorus was associated with a lower risk of KSD. Among female diabetic patients, systolic blood pressure and HOMA2-B were both contributing factors, and ACEIs acted as a protective factor for KSD.

Conclusion

Among Chinese patients with T2DM, approximately 1 in 7 patients was affected by KSD, and the prevalence was twice as high as that in the general Chinese population. The factors associated with KSD varied by sex among T2DM patients. Focusing on these factors is beneficial for reducing the risk of KSD and delaying kidney damage in diabetic patients.

Relationship between Kidney Stone Disease and Arterial Stiffness in a Taiwanese Population

Previous studies examining the association between kidney stone disease (KSD) and arterial stiffness have been limited. Both age and gender have been found to have an impact on KSD, but their influence on the relationship between KSD and increased arterial stiffness is unclear. This study included 6694 subjects from October 2006 to August 2009. The diagnosis of kidney stone was based on the results of ultrasonographic examination. Increased arterial stiffness was defined as right-sided brachial-ankle pulse wave velocity (baPWV) ≥ 14 m/s. Associations between KSD and increased arterial stiffness were analyzed using multiple logistic regression models. KSD was positively related to increased arterial stiffness in both male and female groups (males: odds ratio [OR], 1.306; 95% confidence interval [CI], 1.035–1.649; females: OR, 1.585; 95% CI, 1.038–2.419) after adjusting for confounding factors. Subgroup analysis by age group (<50 and ≥50 years) showed a significant positive relationship only in the groups ≥ 50 years for both genders (males: OR, 1.546; 95% CI, 1.111–2.151; females: OR, 1.783; 95% CI, 1.042–3.054), but not in the groups < 50 years. In conclusion, KSD is associated with a higher risk of increased arterial stiffness in individuals aged ≥ 50 years, but not in those aged < 50 years for both genders.

The status and characteristics of urinary stone composition in China

OBJECTIVES

To explore characteristics of urinary stone composition in China, and determine the effects of gender, age, body mass index (BMI), stone location, and geographical region on stone composition.

PATIENTS AND METHODS

We prospectively used Fourier-transform infrared spectroscopy to analyse stones from consecutive patients presenting with new-onset urolithiasis at 46 hospitals in seven geographical areas of China, between 1 June 2010 and 31 May 2015. Chi-squared tests and logistic regression analyses were used to determine associations between stone composition and gender, age, BMI, stone location, and geographical region.

RESULTS

The most common stone constituents were: calcium oxalate (CaOx; 65.9%), carbapatite (15.6%), urate (12.4%), struvite (2.7%), and brushite (1.7%). CaOx and urate stones occurred more frequently in males, whereas carbapatite and struvite were more common in females (P < 0.01). CaOx and carbapatite were more common in those aged 30-50 and 20-40 years than in other groups. Brushite and struvite were most common amongst those aged <20 and >70 years. The detection rate of urate increased with age, whilst cystine decreased with age. Obese patients were more likely to have urate stones than carbapatite or brushite stones (P < 0.01). CaOx, carbapatite, brushite, and cystine stones were more frequently found in the kidney than other types, whereas urate and struvite were more frequent in the bladder (P < 0.01). Stone composition varied by geographical region.

CONCLUSIONS

The most common stone composition was CaOx, followed by carbapatite, urate, struvite, and brushite. Stone composition differed significantly in patients grouped by gender, age, BMI, stone location, and geographical region.

Fatty acid-binding protein 4 downregulation drives calcification in the development of kidney stone disease

Nephrolithiasis is a significant source of morbidity, and its incidence has increased significantly over the last decades. This rise has been attributed to concurrent increasing rates of obesity, associated with a 3-time risk of developing NL. To date, the mechanism by which obesity is linked to stone formation has not been elucidated. We aimed to utilize a transcriptomics approach to discover the missing link between these two epidemic diseases. We investigated gene expression profiling of nephrolithiasis patients by two RNA-sequencing approaches: comparison between renal papilla tissue with and without the presence of calcified Randall's plaques (RP), and comparison between the papilla, medulla, and cortex regions from within a single recurrent stone forming kidney. Results were overlaid between differently expressed genes found in the patient cohort and in the severely lithogenic kidney to identify common genes. Overlay of these two RNA-sequencing datasets demonstrated there is impairment of lipid metabolism in renal papilla tissue containing RP linked to downregulation of fatty acid binding protein (FABP) 4. Immunohistochemistry of human kidney specimens and microarray analysis of renal tissue from a nephrolithiasis mouse model confirmed that FABP4 downregulation is associated with renal stone formation. In a FABP4 knockout mouse model, FABP4 deficiency resulted in development of both renal and urinary crystals. Our study revealed that FABP4 plays an important, previously unrecognized role in kidney stone formation, providing a feasible mechanism to explain the link between nephrolithiasis and metabolic syndrome.

Obesity and stones

PURPOSE OF REVIEW

The incidence of urolithiasis has shown a prominent increase in the last two to three decades and evidence-based data have clearly indicated the certain role of obesity and overweight in both children and adults. As a certain component of metabolic syndrome, 'obesity' has been found to have a significant impact on the urinary metabolic risk factors which may be important in stone formation. In this present review article, we aimed to evaluate the possible association between obesity and urolithiasis and related risk factors. The epidemiology, pathophysiology, and management of stone disease in obese cases will be discussed in detail.

RECENT FINDINGS

The possible influence of overweight/obesity on the metabolic stone-forming risk factors has been subjected to several studies which in turn well demonstrated the increased risk of stone formation in this population. Although the exact underlying mechanisms are still to be outlined, some certain pathogenetic factors, namely, changes in urinary pH and increased excretion of some urinary stone components have been well demonstrated. Given this increased risk status, these cases require a more comprehensive workup for urolithiasis. Appropriate metabolic evaluation-based medical therapy alongside dietary recommendations will be effective in preventing stone formation.

SUMMARY

Patients suffering from obesity problem have particular risk factors for urolithiasis when compared with their normal-weight counterparts. All efforts should be taken to increase the awareness of this problem and necessary precautions with well-planned treatment plan are the main tasks for urologists.

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.

Number of Metabolic Syndrome Components Is the Central Predictor of the Impact of Metabolic Syndrome on Outcome of Percutaneous Nephrolithotomy in Staghorn Nephrolithiasis

Introduction: How to quantify the impact of metabolic syndrome (MetS) on percutaneous nephrolithotomy (PCNL) is unclear. We aimed to evaluate the quantified effect of the number of MetS components on the outcome of PCNL. Materials and Methods: In this retrospective cohort study, consecutive 606 patients with idiopathic staghorn renal stones undergoing PCNL were included. The participants were divided into two groups: MetS(+) and MetS(-). The number of MetS components were calculated as 0 to 5. Primary outcomes were stone-free rate (SFR) and overall complication rate. Results: MetS, obesity, hypertension, increased triglycerides (TG), decreased high-density lipoprotein cholesterol (HDL), and diabetes mellitus were found in 24.1%, 38.1%, 70.0%, 29.9%, 34.5%, and 26.4% of the patients, respectively. SFR values were comparable between groups. MetS resulted in a higher rate of overall complication (p < 0.001, odds ratio [OR] = 2.4, 95% confidence interval [CI] 1.67-3.69), blood transfusion, urosepsis, larger hemoglobin deficiency, and length of hospital stay. Multivariable analysis confirmed that fasting plasma glucose (FPG) (p = 0.033, OR = 1.164, 95% CI 10.22-1.348) and number of MetS components (p = 0.001, OR = 1.496, 95% CI 1.184-1.890) were independent risk factors, whereas HDL (p = 0.014, OR = 0.428, 95% CI 0.217-0.837) played an independent protective role. Compared with 0, having 3, 4, and 5 MetS components was associated with stepwise increase in complication rate (19.5% vs 34.2%, 41.5%, 62.5%, p = 0.027, 0.006, <0.001; OR = 2.1, 2.9, 6.9). Subgroup analysis showed that MetS(+) patients without complications were associated with lower systolic blood pressure, TG, and FPG (p = 0.010, 0.031, 0.002, respectively). Conclusions: The number of MetS components is the central predictor in assessing both inner severity of MetS and outer risk for PCNL. The number of MetS components is recommended to be calculated on a scale of 0 to 5. Three, four, and five MetS components increase risk for PCNL in a stepwise manner regardless of the presence or absence of obesity. MetS components should be controlled preoperatively.

[Modifiable and non-modifiable risk factors for urolithiasis]

Knowledge of the risk factors for urolithiasis is the key for sufficient metaphylaxis and reduction of recurrence events. Modifiable risk factors include diet, drink quantity, occupation, environmental factors, number of pregnancies and the intestinal microbiome. The treatment of associated diseases, such as the various manifestations of metabolic syndrome can reduce the risk for urolithiasis and recurrences. Knowledge of non-modifiable risk factors, such as gender, ethnicity, positive family history as well as specific genetic defects and polymorphisms of the calcium and phosphate balance enables personalized counselling and follow-up of affected patients.

Nephrolithiasis in the Obese Patient

PURPOSE OF REVIEW

The link between metabolic syndrome (MetS)/obesity and kidney stone disease (KSD) has gained importance over recent years due to the increasing prevalence and healthcare burden worldwide. This review analyses the literature exploring the link between MetS/obesity and KSD and the impact that obesity has on KSD management.

RECENT FINDINGS

Metabolic syndrome has been shown to increase an individual's risk of developing kidney stone disease, with insulin resistance forming a core component of the pathophysiology. The body habitus of an individual also influences the type of intervention that is most appropriate, with flexible ureteroscopy increasingly being the preferred option in obese patients. It is important for urologists to consider the features of metabolic syndrome to effectively manage episodes of KSD in obese patients. In addition, better quality evidence is required to effectively compare different treatment options in this group of patients.

New-onset metabolic risk factors and the incidence of kidney stones: a prospective cohort study

OBJECTIVE

To examine the association of kidney stones with new-onset hypertension, diabetes and obesity.

PARTICIPANTS AND METHODS

This prospective cohort study included participants in the Qingdao Port Cardiovascular Health Study who were aged ≥18 years and had abdominal ultrasonography results in 2013 that were negative for kidney stones. Multivariable Cox regression models with time-dependent covariates were used to estimate the effects of new-onset hypertension, diabetes and obesity on the incidence of kidney stones.

RESULTS

There were 9667 participants without kidney stones in 2013 (mean age 46.2 years; 75.6% men). During a mean (range) follow-up of 33.5 (6-42) months, 676 (7.0%) incident cases of kidney stones were identified. Kidney stones were more frequent among those who had new-onset of a metabolic factor vs those who did not (hypertension: 7.7 vs 6.0%; diabetes: 8.4 vs 6.6%; obesity: 7.4 vs 6.8%). Adjusted Cox models identified that increased risk of kidney stones was associated with new-onset hypertension (adjusted hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.25-2.27), new-onset diabetes (HR 1.78, 95% CI 1.07-2.96), and new-onset obesity (HR 1.78, 95% CI 1.15-2.74).

CONCLUSIONS

New-onset of hypertension, diabetes and obesity were all strongly associated with an increased risk of kidney stones in this prospective cohort study. Results suggest that a substantial proportion of kidney stones are potentially preventable by appropriate control of these metabolic risk factors.

Peculiarities of course of the urolithiasis disease in patients with a solitary kidney and concomitant diabetes mellitus type II

Objective. To analyze the cases histories of urolithiasis disease and its course peculiarities in patients with a solitary kidney, unilateral urolithiasis and concomitant diabetes mellitus type II. Маterials and methods. Retrospective analysis of the cases histories was conducted in 109 patients, suffering urolithiasis disease with concomitant diabetes mellitus type II, of them in 31 patients a solitary kidney was present (Group I), in 78 - unilateral nephrolithiasis (Group II). Results. There was established, that even in adequately corrected hyperglycemia in the patients, having a solitary kidney, the risk for unfavorable course of urolithiasis disease and diabetes mellitus type II is higher, than in patients, having both functioning kidneys. The majority of patients, having a solitary kidney, owe the lowered velocity indices of glomerular filtration and glomerular hyperfiltration, proteinuria and arterial hypertension, what, even in presence of diabetes mellitus with the middle severity course, constitutes a high risk for rapid lowering of renal function. Conclusion. In the urolithiasis disease in the patients with a solitary kidney and concomitant diabetes mellitus type II there have an objectively proven risk for progressing of chronic renal disease. The necessity for the multidisciplinary approach realization of the urologists and endocrinologists activities in determination of personified schemes of treatment in these patients is substantiated.

Novel Risk Loci Identified in a Genome-Wide Association Study of Urolithiasis in a Japanese Population

BACKGROUND

A family history of urolithiasis is associated with a more than doubling of urolithiasis risk, and a twin study estimating 56% heritability of the condition suggests a pivotal role for host genetic factors. However, previous genome-wide association studies (GWAS) have identified only six risk-related loci.

METHODS

To identify novel urolithiasis-related loci in the Japanese population, we performed a large-scale GWAS of 11,130 cases and 187,639 controls, followed by a replication analysis of 2289 cases and 3817 controls. Diagnosis of urolithiasis was confirmed either by a clinician or using medical records or self-report. We also assessed the association of urolithiasis loci with 16 quantitative traits, including metabolic, kidney-related, and electrolyte traits (such as body mass index, lipid storage, eGFR, serum uric acid, and serum calcium), using up to 160,000 samples from BioBank Japan.

RESULTS

The analysis identified 14 significant loci, including nine novel loci. Ten regions showed a significant association with at least one quantitative trait, including metabolic, kidney-related, and electrolyte traits, suggesting a common genetic basis for urolithiasis and these quantitative traits. Four novel loci were related to metabolic traits, obesity, hypertriglyceridemia, or hyperuricemia. The remaining ten loci were associated with kidney- or electrolyte-related traits; these may affect crystallization. Weighted genetic risk score analysis indicated that the highest risk group (top 20%) showed an odds ratio of 1.71 (95% confidence interval, 1.42 to 2.06) - 2.13 (95% confidence interval, 2.00 to 2.27) compared with the reference group (bottom 20%).

CONCLUSIONS

Our findings provide evidence that host genetic factors related to regulation of metabolic and crystallization pathways contribute to the development of urolithiasis.

Association of sirtuin 1 gene polymorphisms with nephrolithiasis in Eastern chinese population

Sirtuin 1 (SIRT1), an NAD⁺-dependent deacylase, has been identified to be associated with renal tubular inflammatory conditions and metabolic disorders, which are risk factors of nephrolithiasis. To further confirm the role of the SIRT1 in kidney stone formation, the expression of SIRT1 was analyzed based on a mouse model and the genetic polymorphisms of SIRT1 gene was compared between patients with kidney stones and controls. The calcium oxalate (CaOx) crystal-induced renal injury model was established to analyzed the expression of SIRT1 in the kidney tissue of both wild-type and ApoE(−/−) mice. And a total of 430 Eastern Chinese subjects (215 patients with nephrolithiasis and 215 age- and gender-matched controls) were recruited for the present study to investigate the associations between 6 common single nucleotide polymorphisms (SNPs) (i.e., rs10509291, rs3740051, rs932658, rs33957861, rs3818292 and rs1467568) in the SIRT1 gene and the incidence of kidney stones. Pairwise linkage disequilibrium and the haplotypes of the 6 SNPs were also analyzed. The genotypes of SIRT1 gene polymorphisms were analyzed by a Snapshot assay. Reduced expression of SIRT1 was observed in the kidney of the mice in the crystal group, revealing the potential role of SIRT1 in the nephrolithiasis. However, we did not find a significant association between the 6 SNPs of the SIRT1 gene and kidney stone formation in the Eastern Chinese population.

Impact of dyslipidemia on 24-h urine composition in adults without urolithiasis

PURPOSES

To evaluate the influence of dyslipidemia on 24-h urine composition in adults who were non-stone formers (NF).

METHODS

Samples for 24-h urine composition were analyzed from 584 NF adults without urolithiasis in a national six-city-based epidemiologic study. The samples were divided into groups based on total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL). The groups were compared based on demographic data and each component of 24-h urinalysis.

RESULTS

The numbers of participants in high TG, high TC, high LDL, and low HDL were 106, 175, 147, and 59, respectively. The high TG group had increased urinary excretions of oxalate [mean difference (MD) = 0.032 mmol, 95% confidence interval (CI): 0.000-0.065] and potassium (MD = 4.298 mmol, 95%CI: 0.182-8.414). Increased urinary excretion of calcium (MD = 0.531 mmol, 95%CI: 0.061-1.001), sodium (MD = 41.561 mmol, 95%CI: 9.179-73.942), and chloride (MD = 45.209 mmol, 95%CI: 12.118-78.299) were found in the high TC group. Interestingly, the high LDL group had a decreased urinary excretion of calcium (MD = - 0.573 mmol, 95%CI: -1.048 to - 0.097), oxalate (MD = - 0.038 mmol, 95%CI: -0.07 to - 0.006), sodium (MD = - 53.285 mmol, 95%CI: -85.823 to - 20.748), and chloride (MD = - 55.809 mmol, 95%CI: -89.035 to - 22.583). Increased urinary excretions of citrate (MD = 0.455 mmol, 95%CI: 0.076-0.835) and magnesium (MD = 0.697 mmol, 95%CI: 0.244-1.149) were found in the low HDL group.

CONCLUSIONS

The present study first investigated the effects of dyslipidemia on 24-h urinalysis in NF adults. Of note, high LDL and low HDL were found to be adversely related to kidney stone formation. However, people with high TG and high TC should be cautious of getting kidney stones.

Association between blood lipid profile and urolithiasis: A systematic review and meta-analysis of observational studies

The objective of this study was to pool individual studies regarding the association of blood lipid profiles with urolithiasis to carry out a systematic review and meta-analysis. We searched MEDLINE, PubMed, Embase and Cochrane Library to identify the relevant studies up to November 2017. Studies that met all inclusion criteria were chosen, and a pooled analysis of the odds ratio between urolithiasis and dyslipidemia traits was calculated. A total of 11 observational studies (seven cross-sectional, three cohort, one case-control) with a total of 282 479 participants were examined. The overall pooled analysis of eight studies showed that high triglyceride was associated with increased estimated risk of urolithiasis (odds ratio 1.287, 95% CI 1.073-1.544; P = 0.007). Estimates of the total effect size were consistent in the sensitivity analysis. No evidence of publication bias was detected. The overall pooled analysis of nine studies showed low high-density lipoprotein was weakly associated with increased estimated risk of urolithiasis (odds ratio 1.171, 95% CI 1.010-1.358; P = 0.032). The sensitivity analysis showed conflicting results. No evidence of publication bias was detected. Three studies on the association between any dyslipidemia traits and urolithiasis showed a significant association (odds ratio 1.309, 95% CI 1.202-1.425; P < 0.001). The present meta-analysis showed that patients with higher triglyceride and lower high-density lipoprotein had an increased estimated risk of urolithiasis. A triglyceride-urolithiasis association was found to be more coherent and consistent compared with the high-density lipoprotein-urolithiasis association. Although somewhat contradictory results have been found, the meta-analysis is encouraging for evaluating urolithiasis as a systemic disorder. Further well-designed prospective randomized controlled or cohort studies are necessary to better elucidate the causal association of dyslipidemia and urolithiasis.

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.

Metabolic syndrome and uric acid nephrolithiasis: insulin resistance in focus

Uric acid nephrolithiasis (UAN) is an increasingly common disease in ethnically diverse populations and constitutes about 10% of all kidney stones. Metabolic syndrome and diabetes mellitus are accounted among the major risk factors for UAN, together with environmental exposure, individual lifestyle habits and genetic predisposition. The development and overt manifestation of UAN appears to stem on the background of insulin resistance, which acts at the kidney level by reducing urinary pH, thus hampering the ability of the kidney to generate renal ammonium in response to an acid load. Unduly acidic urinary pH and overt UAN are both considered renal manifestations of insulin resistance. The mechanisms underlying increased endogenous acid production and/or defective ammonium excretion are yet to be completely understood. Although the development of UAN and, more in general, of kidney stones largely recognizes modifiable individual determining factors, the rising prevalence of diabetes, obesity and accompanying metabolic disorders calls for the identification of novel therapeutic approaches and intervention targets. This review aims at providing an updated picture of existing evidence on the relationship between insulin resistance and UAN in the context of metabolic syndrome and in light of the most recent advancements in our understanding of its genetic signature.

Obesity and kidney stone disease: a systematic review

INTRODUCTION

Currently, abdominal obesity has reached an epidemic stage and obesity represents an important challenge for worldwide health authorities. Epidemiologic studies have demonstrated that the stone risk incidence increases with Body Mass Index, through multiple pathways. Metabolic syndrome and diabetes are associated with an increased renal stones disease incidence. The aim of this systematic review was to investigate the prevalence, morbidity, risk factors involved in the association between obesity and urolithiasis.

EVIDENCE ACQUISITION

The search involved finding relevant studies from MEDLINE, EMBASE, Ovid, the Cochrane Central Register of Controlled Trials, CINAHL, Google Scholar, and individual urological journals between January 2001 and May 2017. The inclusion criteria were for studies written in the English language, reporting on the association between obesity and urinary stones.

EVIDENCE SYNTHESIS

The underlying pathophysiology of stone formation in obese patients is thought to be related to insulin resistance, dietary factors, and a lithogenic urinary profile. Uric acid stones and calcium oxalate stones are observed frequently in these patients. Insulin resistance is thought to alter the renal acid-base metabolism, resulting in a lower urine pH, and increasing the risk of uric acid stone disease. Obesity is also associated with excess nutritional intake of lithogenic substances and with an increase in urinary tract infection incidence. Recent studies highlighted that renal stone disease increases the risk of myocardial infarction, progression of chronic kidney disease, and diabetes. Contemporary, bariatric surgery has been shown to be associated with hyperoxaluria and oxalate nephropathy. Certainly, the many health risks of obesity, including nephrolithiasis, will add more burden on urologists and nephrologists.

CONCLUSIONS

Obesity related nephrolithiasis seems to necessitate weight loss as primary treatment, but the recognition of the associated complications is necessary to prevent induction of new and equally severe medical problems. The optimal approach to obesity control that minimizes stone risk needs to be determined in order to manage obesity-induced renal stones 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.

Obesity and metabolic stone disease

PURPOSE OF REVIEW

In this article, we aim to review the data regarding associations between obesity and nephrolithiasis to assist with workup and treatment of these intersecting disorders. As obesity has a multifactorial influence on the risk for urinary stone disease, the complicated mechanisms will be discussed to improve diagnosis and management.

RECENT FINDINGS

Obesity and metabolic syndrome interact with nephrolithiasis risk factors to produce a myriad of bodily responses that induce stone formation. For this reason, many societies recommend prompt metabolic workup to evaluate the precise causes of stone formation. Data have shown that dietary and directed medical therapies can produce an excellent therapeutic response in this patient population, although the response may be blunted compared with nonobese patients.

SUMMARY

Given the increasing number of obese and overweight patients, the urologist should be familiar with the pathophysiology, workup, and treatment of metabolic stone disease in this population, which are outlined here.

The effects of HAP and macrophage cells to the expression of inflammatory factors and apoptosis in HK-2 cells of vitro co-cultured system

This study developed an in vitro system by co-culturing HK-2 cells with different concentration of hydroxyapatite (HAP) and/or macrophage cells to simulate the internal environment of urolithiasis as far as possible, investigating the regulatory effects of macrophage cells on HAP-induced expression of relative inflammatory factors of HK-2 cells. The control group (H group) was only comprised of HK-2 cells. Experimental groups included co-culturing HK-2 cells and macrophage cells (H + M group), co-culturing HK-2 cells and HAP (H + A group), co-culturing macrophage cells and HAP (M + A group), and co-culturing HK-2 cells and macrophage cells with HAP (H + M + A group). In the H + A, M + A, and H + M + A group, we set the concentration of HAP as 5 μg/cm² (A1) and 10 μg/cm² (A2). After co-culturing for 2, 4, and 6 h, we detected the expression of CCL-2 in the liquid by ELISA. We tested the expression of LDH and ROS to evaluate the damage of HK-2 cells. We assessed the apoptosis of HK-2 cells using DAPI staining assay, flow cytometry, and the rate of BAX/BCL-2. Western Blotting detected OPN, Fetuin-A, BAX, and BCL-2 of HK-2 cells. The expression of CCL-2 in the medium of H + A1 and H + A2 group increased significantly compared with the control (P < 0.05); CCL-2 of M + A1 and M + A2 group was higher than the H + A1 and H + A2 group (P < 0.05). The expression of CCL-2 in H + M + A1 and H + M + A2 group was also higher than M + A1 and M + A2 group (P < 0.05). Compared with control, the expression of OPN, LDH release, the ratio of BAX/BCL-2, and the generation of ROS in HK-2 cells increased in a dose- and time-dependent manner. Compared with the control, the expression of Fetuin-A decreased in various degrees at different incubation periods. Especially when co-culturing for 6 h, Fetuin-A decreased most seriously in the H + M + A1 group. (1) The HAP can induce the HK-2 cells oxidative stress and inflammatory damage and apoptosis, when adding the macrophages to co-culture, macrophage cells can aggravate the damage and apoptosis of the HK-2 cells. (2) After the stimulation of HAP, the expression of OPN in HK-2 cells increased in a time- and dose-dependent manner; macrophage cells can aggravate the increase of OPN in HK-2 cells. (3) In the HAP and HK-2 cells co-cultured system, the low-level Fetuin-A of HK-2 cells may be related to the excessive consumption of Fetuin-A in the process of HAP-induced renal tubular epithelial cell excessive oxidative stress, inflammatory injury, and cell apoptosis. When adding macrophage cells to co-culture, Fetuin-A decreased even more seriously, it reminds us that macrophage cells can slightly regulate the expression of Fetuin-A in the HK-2 cells.

Nephrolithiasis and risk of hypertension: a meta-analysis of observational studies

Background

Observational studies have demonstrated an association between nephrolithiasis and hypertension. The aim of this meta-analysis was to summarize all available evidence.

Methods

PubMed, EMBASE, the Cochrane Central Register of Controlled Trials databases, and the reference lists of relevant articles were searched to identify observational studies that reported study-specific risk estimates comparing the risk of hypertension in patients with nephrolithiasis. We used a random-effect model to pool the study-specific risk estimates. We also assessed the potential heterogeneity by subgroup analyses, meta-regression analyses, and sensitivity analyses.

Results

A total of 7 articles including 9 studies (n = 313,222 participants) were eventually identified in this meta-analysis. In comparison with the patients who did not have nephrolithiasis, nephrolithiasis significantly increased the risk of hypertension (OR, 1.43; 95% CI, 1.30–1.56), with significant heterogeneity between these studies (I² = 83.5%, P <0.001). The heterogeneity reduced in subgroups of cohort studies, USA, large sample size trials, men, and adjustment for confounding factors ≥ 5. Sensitivity analysis further demonstrated the results to be robust.

Conclusions

Nephrolithiasis is associated with increased risk of hypertension. Future randomized, high-quality clinical trials are encouraged to definitively clarify the relationship between nephrolithiasis and hypertension, which may influence clinical management and primary prevention of hypertension in nephrolithiasis patients.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0762-8) contains supplementary material, which is available to authorized users.

Chronological Trends in Clinical and Urinary Metabolic Features over 20 Years in Korean Urolithiasis Patients

Urolithiasis is common and is becoming more prevalent worldwide. This study assessed the chronological trends in clinical and urinary metabolic features over 20 years in Korean urolithiasis patients. We performed a retrospective analysis of 4,076 patients treated at our clinic from 1996 to 2015. Urinary metabolic data and stone analysis data were available for 1,421 and 723 patients (34.9% and 17.7%), respectively. Patients were categorized into 4 groups according to the date of initial diagnosis: group 1 (1996-2000, n = 897), group 2 (2001-2005, n = 1,018), group 3 (2006-2010, n = 1,043), and group 4 (2011-2015, n = 1,118). Incidental detection of uric acid renal stones has become more prevalent in the past 10 years, accompanied by an increase in body mass index and age at diagnosis. Similarly, the prevalence of diabetes mellitus and of hypertension increased from one group to the next throughout the study period. Levels of 24-hour urinary excretion of sodium, calcium, uric acid, and oxalate have decreased significantly over the study period. The incidence of urinary metabolic abnormalities also showed an identical tendency. The proportion of stones composed of uric acid increased over the study period. In conclusion, incidental detection of uric acid renal stones has become more prevalent in Korea in the past 20 years. Urinary excretion of lithogenic constituents and the incidence of urinary metabolic abnormalities have decreased significantly over this period.

Association between multiple chronic conditions and urolithiasis

PURPOSE

Given the risk factors for stone disease, it is possible that multiple chronic condition (MCC) patients are at increased risk of developing new, recurrent, or worsening urolithiasis. The purpose of our investigation was to evaluate the relationship between MCCs and urolithiasis.

METHODS

Retrospective cohort using outpatient claims data for all adult members (≥18 years) of the Beaumont Employee Health Plan who received outpatient care between 2008 and 2013. Multiple logistic regression adjusted for age, sex, obesity, hyperlipidemia, hypertension, and diabetes was used to assess the relationship between number of comorbid chronic conditions and urolithiasis.

RESULTS

The cohort consisted of 34,173 adult patients with an average age of 40.4 years and 61.2% being female. The prevalence of urolithiasis was 3.1% (n = 1059). Patients with urolithiasis had a significantly higher average number of comorbid chronic conditions (2.4 vs. 1.3, p < 0.001) than patient without urolithiasis. Both crude (OR 1.34; 95% CI 1.30-1.38) and adjusted logistic regression models (OR 1.37; 95% CI 1.31-1.44) revealed a significant relationship between number of comorbid chronic conditions and urolithiasis. More than 81% of patients had one or more co-occurring chronic conditions; the most common MCC combinations associated with urolithiasis were hypertension-hyperlipidemia, chronic back pain, and hyperlipidemia.

CONCLUSION

We report an association between MCCs and urolithiasis. Future research is needed to better understand the temporality and strength of this relationship. Physicians should recognize that urolithiasis and MCCs are closely related and therefore may consider more aggressive primary prevention of chronic disease and improved management of MCCs.

Epidemiology of stone disease across the world

Nephrolithiasis is a highly prevalent disease worldwide with rates ranging from 7 to 13% in North America, 5-9% in Europe, and 1-5% in Asia. Due to high rates of new and recurrent stones, management of stones is expensive and the disease has a high level of acute and chronic morbidity. The goal of this study is to review the epidemiology of stone disease in order to improve patient care. A review of the literature was conducted through a search on Pubmed^®, Medline^®, and Google Scholar^®. This review was presented and peer-reviewed at the 3rd International Consultation on Stone Disease during the 2014 Société Internationale d'Urologie Congress in Glasgow. It represents an update of the 2008 consensus document based on expert opinion of the most relevant studies. There has been a rising incidence in stone disease throughout the world with a narrowing of the gender gap. Increased stone prevalence has been attributed to population growth and increases in obesity and diabetes. General dietary recommendations of increased fluid, decreased salt, and moderate intake of protein have not changed. However, specific recommended values have either changed or are more frequently reported. Geography and environment influenced the likelihood of stone disease and more information is needed regarding stone disease in a large portion of the world including Asia and Africa. Randomized controlled studies are lacking but are necessary to improve recommendations regarding diet and fluid intake. Understanding the impact of associated conditions that are rapidly increasing will improve the prevention of stone disease.

Blood pressure and urolithiasis in children

INTRODUCTION

Urolithiasis is a condition that is most commonly found in adults, but is becoming increasingly prevalent in children. Little is known about the relationship between blood pressure (BP) and urolithiasis in children.

OBJECTIVES

The aim was to evaluate the relationship between urolithiasis and BP, and to determine the association of BP with 24-h urine parameters in children.

METHODS

We retrospectively analyzed BP and 24-h urine data from children <18 years with and without urolithiasis from 2004 to 2015 at a single tertiary center. Children with a diagnosis of non-glomerular hematuria without history of urolithiasis were chosen as the control group. Non-stone formers were excluded if they presented with any abnormal 24-h urine data or kidney disease. Casual BP, BP index (BPi), and 24-h urine parameters were compared between groups using t-tests. Multiple regression analyses adjusting for age, sex and body mass index (BMI) z-score evaluated the association of BP with urolithiasis and urine electrolytes.

RESULTS

The urolithiasis group (N = 71) was significantly older, taller and heavier than the non-stone former group (N = 53) (Table). Systolic BP and diastolic BP in stone formers were significantly greater than in non-stone formers, respectively (p = 0.019). Additionally, systolic BPi was significantly higher in the urolithiasis group (p = 0.03) but there was no significant difference in diastolic BPi (p = 0.45). Urolithiasis was a significant predictor of systolic BPi in the adjusted model (β = 0.04, 95% CI 0.001-0.07). In stone formers, systolic BP and systolic BPi were directly associated with 24-h urine sodium, oxalate/1.73 m², and uric acid (all p < 0.05). Urine calcium was not associated with any BP parameter.

DISCUSSION

The findings are consistent with previous studies in adults that examined the correlation between blood pressure and kidney stones. The results of this study also showed that blood pressure was positively associated with urine sodium, oxalate, and uric acid. Interestingly, contrary to adult literature, our hypothesis which postulated that blood pressure would be associated with an increase in urine calcium was not supported by our findings. The small sample size is a study limitation and the use of healthy controls as a comparison would have been ideal.

CONCLUSIONS

Blood pressure was directly associated with urolithiasis children. Greater BP values were also associated with abnormalities in 24-h urine oxalate, uric acid, and sodium values. Interestingly, BP was not associated with urine calcium in this population.

Analysis of altered microRNA expression profiles in the kidney tissues of ethylene glycol-induced hyperoxaluric rats

Calcium oxalate stones account for >80% of urinary stones, however the mechanisms underlying their formation remains to be elucidated. Hyperoxaluria serves an important role in the pathophysiological process of stone formation. In the present study, differences in the miRNA expression profiles between experimental hyperoxaluric rats and normal rats were analyzed, in order to identify target genes and signaling pathways involved in the pathogenesis of hyperoxaluria. Ethylene glycol and ammonium chloride was fed to male hyperoxaluric rats (EXP) and normal age-matched male rats (CON). The oxalate concentration in the urine of each experimental rat was collected every 24 h and measured on day 14. Three rats exhibiting the highest concentrations were selected for microarray analysis. Microarray analysis was performed to evaluate differences in the expression of microRNA (miRNA) in the kidney tissues from EXP and CON groups, and miRNAs that exhibited a >2-fold or a <0.5-fold alteration in expression between these groups were screened for differential expression patterns according to the threshold P-values. Reverse transcription-quantitative polymerase chain reaction analysis was employed to confirm the microarray results. In order to predict the potential role of miRNAs in pathophysiological processes, gene ontology (GO), pathway and target prediction analyses were conducted. A total of 28 miRNAs were observed to be differentially expressed (>2-fold change) between EXP and CON groups. Among these miRNAs, 20 were upregulated and 8 were downregulated. GO and pathway analyses revealed that the insulin resistance and phosphatidylinositol-bisphosphonate 3-kinase/AKT serine threonine kinase signaling pathways were potentially associated with miRNA regulation in this setting. In conclusion, the results of the present study identified differentially expressed miRNAs in hyperoxaluric rats, and provided a novel perspective for the role of miRNAs in the formation of calcium oxalate stones.

Impact of metabolic syndrome and its components on kidney stone in aging Taiwanese males

OBJECTIVES

Metabolic syndrome (MtS) and kidney stone are two common aging diseases with male dominant. This is the first study regarding the potential impact of MtS and its components on kidney stone in aging Chinese population.

METHODS

A total of 694 males with a mean age of 55.6 years were enrolled. The definition of MtS was according to the modified criteria developed by the Bureau of Health Promotion in Taiwan. Subjects were classified as having a disease of kidney stones according to diagnosis by a physician with available medical records or evidence from ultrasonography judged by an investigator of urologist.

RESULTS

Using age-adjusted multivariate logistic regression analysis, our results showed that subjects with kidney stone had significantly higher prevalence of MtS (p = 0.04, OR = 1.74, 95% CI: 1.0 1-3.00). The presence of MtS had significant correlation with kidney stone (p = 0.01, OR = 1.83, 95% CI: 1.1 4-2.93), which were associated with the increment of MtS components (p < 0.01). After adjusting for age and testosterone level, abnormal blood pressure (BP) was the most significantly independent component of MtS for kidney stone among the MtS components (p < 0.01, OR = 2.81, 95% CI: 1.46-5.39).

CONCLUSIONS

In aging Taiwanese males, the presence of MtS and its components are strongly associated with kidney stone. Abnormal BP is the most significant risk component of MtS for kidney stone.

Genome-Wide Gene Expression Profiling of Randall's Plaques in Calcium Oxalate Stone Formers

Randall plaques (RPs) can contribute to the formation of idiopathic calcium oxalate (CaOx) kidney stones; however, genes related to RP formation have not been identified. We previously reported the potential therapeutic role of osteopontin (OPN) and macrophages in CaOx kidney stone formation, discovered using genome-recombined mice and genome-wide analyses. Here, to characterize the genetic pathogenesis of RPs, we used microarrays and immunohistology to compare gene expression among renal papillary RP and non-RP tissues of 23 CaOx stone formers (SFs) (age- and sex-matched) and normal papillary tissue of seven controls. Transmission electron microscopy showed OPN and collagen expression inside and around RPs, respectively. Cluster analysis revealed that the papillary gene expression of CaOx SFs differed significantly from that of controls. Disease and function analysis of gene expression revealed activation of cellular hyperpolarization, reproductive development, and molecular transport in papillary tissue from RPs and non-RP regions of CaOx SFs. Compared with non-RP tissue, RP tissue showed upregulation (˃2-fold) of LCN2, IL11, PTGS1, GPX3, and MMD and downregulation (0.5-fold) of SLC12A1 and NALCN (P<0.01). In network and toxicity analyses, these genes associated with activated mitogen-activated protein kinase, the Akt/phosphatidylinositol 3-kinase pathway, and proinflammatory cytokines that cause renal injury and oxidative stress. Additionally, expression of proinflammatory cytokines, numbers of immune cells, and cellular apoptosis increased in RP tissue. This study establishes an association between genes related to renal dysfunction, proinflammation, oxidative stress, and ion transport and RP development in CaOx SFs.

Differential Roles of Peroxisome Proliferator-Activated Receptor-α and Receptor-γ on Renal Crystal Formation in Hyperoxaluric Rodents

Peroxisome proliferator-activated receptors (PPARs) and related inflammatory and oxidative molecule expression were investigated in a hyperoxaluric rodent model to evaluate the in vivo efficacy of PPAR agonists in preventing renal crystal formation. PPAR expression was examined in a mouse hyperoxaluria kidney stone model induced by daily intra-abdominal glyoxylate injection. Therapeutic effects of the PPARα agonist fenofibrate and PPARγ agonist pioglitazone were also assessed in a 1% ethylene glycol-induced rat model of hyperoxaluria. Crystal formation, inflammation, cell injury, apoptosis, and oxidative stress were compared to those of vehicle-treated controls. Quantitative reverse transcription-polymerase chain reaction revealed that PPARα and PPARγ expression decrease and increase, respectively, during crystal formation in hyperoxaluric kidneys. In addition, PPARα localized to the cytoplasm of both proximal and distal tubular cells, whereas PPARγ accumulated in the nucleus of proximal tubular cells. Furthermore, renal crystal formation was significantly less prevalent in pioglitazone-treated rats but higher in the fenofibrate-treated and fenofibrate/pioglitazone-cotreated groups compared to controls, thus indicating that pioglitazone, but not fenofibrate, markedly decreased cell inflammation, oxidative stress, and apoptosis. Collectively, the results demonstrated that PPARγ suppressed renal crystal formation via its antioxidative and anti-inflammatory effects; however, the renotoxicity of PPARα may elicit the opposite effect.

Metabolic syndrome and nephrolithiasis

Problem

This review focuses on the association between the metabolic syndrome (MS) and nephrolithiasis.

Findings

Associations between nephrolithiasis and systemic diseases are recognized, including atherosclerosis, cardiovascular (CV) disease, hypertension (HNT), diabetes mellitus (DM)—composite risk factors grouped as the MS. Kidney stones incidence is increasing in this particularly high risk group. Those with stones are prone to the disease and those with the systemic disease are at risk for stone formation, with the highest incidence in persons with multiple traits of the MS. Pathophysiologic explanations for the increased stone risk related to MS are likely complex and dynamic.

Conclusions

Kidney stones disproportionately affect persons with some or all traits of MS. One unifying theory may be of a common systemic malfunction of inflammation and tissue damage as an underlying mechanism, but it is unlikely to be the only mechanistic explanation. Further research is needed to investigate this and other hypotheses that go beyond population based and urine physiochemical studies in order to elucidate the mechanisms behind the individual disease states themselves.

Urolithiasis--an interdisciplinary diagnostic, therapeutic and secondary preventive challenge

BACKGROUND

The prevalence of urolithiasis in Germany is 4.7%; its incidence has trebled in the last three decades. The risk of recurrence is 50-80%, depending on the type of stone, unless secondary prevention is instituted. Risk-adapted secondary prevention lowers this risk to 10-15%.

METHODS

This review is based on publications retrieved by a selective search in PubMed using the key words "urolithiasis," "urinary stones," "epidemiology," "lithogenesis," "biominerals," "risk factors," and "diagnosis, therapy, metaphylaxis." These publications were evaluated with the aid of the urolithiasis guideline of the European Association of Urology.

RESULTS

Acute renal colic can usually be diagnosed without sophisticated equipment. Stones can be dealt with by a variety of techniques depending on their size and location, including extracorporeal shock-wave lithotripsy, ureterorenoscopy, percutaneous nephrolitholapaxy, and open surgery. Most ureteric stones of diameter up to 5 mm pass spontaneously. 75% of patients have no complications. The basic evaluation needed for secondary prevention can be carried out by any physician on an ambulatory basis. In the 25% of patients who have complications, a more extensive interdisciplinary evaluation of metabolic parameters should be performed in a clinical center for urinary stones.

CONCLUSION

Urolithiasis has many causes and can be treated in many different ways. An extensive metabolic work-up is often necessary for secondary prevention. The various treatment options must be considered for their suitability in each individual patient. Robust data are now available on surgical and interventional methods, but there are as yet no high-quality trials of secondary prevention. Further research should concentrate on the etiology and pathogenesis of urolithiasis.

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

INTRODUCTION

Worldwide obesity has more than doubled since 1980 with more than 600 million obese patients in 2014. Metabolic syndrome (MetS) is the co-occurrence of metabolic abnormalities, including centrally distributed obesity, hypertension, dyslipidemia, and hyperglycemia. With a concurrent rise in the incidence of kidney stone disease, we wanted to conduct a systematic review focused on the association of MetS to nephrolithiasis.

MATERIALS AND METHODS

A systematic review was performed according to the Cochrane and preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines on all English language articles for the following relevant keywords: association, metabolic syndrome, metabolic syndrome traits, syndrome X, nephrolithiasis, kidney stones, and renal calculi. Our inclusion criteria were studies comparing the prevalence of kidney stone disease in patients with and without MetS.

RESULTS

The initial literature search identified 355 potentially relevant studies. After screening, 22 full text articles were reviewed and 6 (219,255 patients) were included in the final review. All studies displayed increasing odds of nephrolithiasis with increasing number of MetS traits, where patients with three or more MetS traits tended to have a higher prevalence of nephrolithiasis. Studies also showed different significant components of MetS contributing to nephrolithiasis.

CONCLUSIONS

Our review shows a definite association of MetS with kidney stone disease. Although multifactorial in etiology, lifestyle and dietary factors seem to be increasingly important in prevention of stone disease.

Dietary recommendations and treatment of patients with recurrent idiopathic calcium stone disease

This review describes the various dietary regimens that have been used to advise patients on how to prevent the recurrence of their calcium-containing kidney stones. The conclusion is that although there is some general advice that may be useful to many patients, it is more efficacious to screen each patient individually to identify his/her main urinary, metabolic, nutritional, environmental, and lifestyle risk factors for stone-formation and then tailor specific advice for that particular patient based on the findings from these investigations. If the patient can be motivated to adhere strictly to this conservative approach to the prophylactic management of their stone problem over a long time period, then it is possible to prevent them from forming further stones. This approach to stone management is considerably less expensive than any of the procedures currently available for stone removal or disintegration. In the UK, for each new stone episode prevented by this conservative approach to prophylaxis it is calculated to save the Health Authority concerned around £2000 for every patient treated successfully. In the long term, this accumulates to a major saving within each hospital budget if most stone patients can be prevented from forming further stones and when the savings are totalled up country-wide saves the National Exchequer considerable sums in unclaimed Sick Pay and industry a significant number of manpower days which would otherwise be lost from work. It is also of immense relief and benefit to the patients not to have to suffer the discomfort and inconvenience of further stone episodes.

The Effect of Metabolic Syndrome on the Success and Complications of Percutaneous Nephrolitotomy

BACKGROUND

The aim of this study was to investigate the effect of Metabolic syndrome (MetS) on the success and complications of percutaneous nephrolithotomy (PNL).

METHODS

Two hundred ten patients who had undergone PNL for kidney stones in our clinic between May 2012 and May 2014 were retrospectively analyzed. The patients were divided into two groups based on whether they had diagnostic criteria for MetS. All patients had lower pole kidney stones between 15 and 20 mm. Complication rates between groups were evaluated using a modified Clavien grading system.

RESULTS

Group1 was a standard PNL group and group 2 consisted of patients with MetS. Mean stone size was 293.25 ± 102.4 mm(2) for group 1 and 301.10 ± 169.5 mm(2) for group 2 (p < 0.05). Mean hospitalization days, fluoroscopy duration, and mean hematocrit loss were significantly higher in group 2. Mean operative time and need for blood transfusions were higher in group 2 but statistically insignificant. One hundred twenty five patients in group 1 (96.1%) and 72 patients in group 2 (90%) obtained stone-free state.

CONCLUSIONS

Our study results reveal an increase in complications and morbidity for patients with MetS during PNL.

Impact of nephrolithiasis on kidney function

Background

Kidney stone disease has been associated with reduced kidney function and chronic kidney disease (CKD). The objective of the study was to examine kidney function, body mass index (BMI) and the prevalence of cardiovascular disease, hypertension and diabetes in recurrent kidney stone formers.

Methods

A cross-sectional, case-control study comparing measures of kidney function, BMI and comorbid conditions was conducted in 195 kidney stone patients aged 18 to 70 years with recurrent clinical stone events and 390 age- and gender-matched controls. Wilcoxon-Mann-Whitney, chi-square tests and analysis of covariance were used to compare serum creatinine (SCr) and estimated glomerular filtration rate (eGFR) between the groups.

Results

The median age of stone formers was 51 (range, 19–70) years and 108 (55 %) were males. Seventy patients (36 %) had experienced 2–4 clinical stone events, 41 (21 %) 5–10 episodes and 84 (43 %) more than 10. The median SCr was 75 (41–140) μmol/L in the stone formers and 64 (34–168) μmol/L in the control group (p < 0.001). The mean eGFR was 87 ± 20 and 104 ± 22 mL/min/1.73 m² in the stone formers and controls, respectively (p < 0.001). After adjustment for body size and comorbid conditions, the difference in SCr and eGFR between cases and controls remained highly significant (p < 0.001). The prevalence of CKD was 9.3 % among stone formers compared with 1.3 % in the control group (P < 0.001). Hypertension and diabetes were significantly more prevalent among the cases that also had higher BMI than controls.

Conclusions

Recurrent kidney stone formers have a significantly lower level of kidney function and a markedly higher prevalence of CKD than age- and gender-matched control subjects. The observed deleterious effect of kidney stones on kidney function appears to be independent of comorbid conditions.

Proinflammatory and Metabolic Changes Facilitate Renal Crystal Deposition in an Obese Mouse Model of Metabolic Syndrome

PURPOSE

To clarify metabolic syndrome induced stone formation mechanisms we investigated the metabolic and immunohistochemical characteristics associated with renal crystal deposition using a model of mice with metabolic syndrome administered a high fat diet and ethylene glycol.

MATERIALS AND METHODS

Ob/Ob mice with Leptin gene deficiencies and metabolic syndrome related characteristics were compared with wild heterozygous lean mice. Four study groups were fed standard food and water (control group), a high fat diet and normal water (high fat diet group), 1% ethylene glycol and standard food (ethylene glycol group) or a high fat diet and 1% ethylene glycol (high fat diet plus ethylene glycol group). Blood, urine and kidney samples were taken after 14 days.

RESULTS

Ob/Ob mice in the high fat diet plus ethylene glycol group showed diffuse renal crystal depositions. Lean and Ob/Ob mice in the high fat diet plus ethylene glycol group showed significant excretion of urinary calcium oxalate crystals. Ob/Ob mice had significant hypercalciuria, hyperphosphaturia and hyperlipidemia, massive lipid fragments in tubular lumina and fat droplets in renal tubular cells. Ob/Ob mice in the high fat diet plus ethylene glycol group had markedly increased expression of osteopontin, monocyte chemoattractant protein-1, interleukin-6 and tumor necrosis factor-α. In Ob/Ob mice the number of proinflammatory macrophages was considerably elevated.

CONCLUSIONS

We induced renal crystal deposition in mice with metabolic syndrome using a high fat diet and ethylene glycol. Increases in luminal mineral and lipid density, and proinflammatory adipocytokines and macrophages facilitated renal crystal formation in mice with metabolic syndrome.