Sodium-glucose cotransporter 2 inhibitors and risk of nephrolithiasis.

AIMS/HYPOTHESIS: Sodium-glucose cotransporter 2 inhibitors (SGLT2Is) may reduce nephrolithiasis risk by increasing urine flow. We aimed to investigate whether initiation of SGLT2I was associated with reduced nephrolithiasis risk. METHODS: We conducted an active-comparator new-user cohort study using the Danish health registries in the period 11 November 2012 to 31 December 2018. Individuals aged ≥40 years initiating SGLT2Is or glucagon-like peptide-1 receptor agonists (GLP1 RAs) were followed from treatment initiation until an inpatient or outpatient diagnosis of nephrolithiasis, death, emigration or end of study. New users of SGLT2Is were matched 1:1 on propensity scores to new users of GLP1 RAs. In supplementary analyses, risk of recurrent nephrolithiasis was assessed in individuals with a history of nephrolithiasis before treatment initiation. RESULTS: We identified 24,290 and 19,576 eligible users of SGLT2Is and GLP1 RAs, respectively. After matching, 12,325 patient pairs remained. The median age was 61 years and median follow-up was 2.0 years. The nephrolithiasis rate was 2.0 per 1000 person-years in SGLT2I initiators compared with 4.0 per 1000 person-years in GLP1 RA initiators, with a rate difference of -1.9 per 1000 person-years (95% CI -2.8, -1.0) and an HR of 0.51 (95% CI 0.37, 0.71). For recurrent nephrolithiasis (n = 731 patient pairs), the rate difference was -17 per 1000 person-years (95% CI -33, -1.5) and the HR was 0.68 (95% CI 0.48, 0.97). CONCLUSIONS/INTERPRETATION: Initiation of treatment with SGLT2Is was associated with a clinically significant reduced risk of incident and recurrent nephrolithiasis.

Glycine suppresses kidney calcium oxalate crystal depositions via regulating urinary excretions of oxalate and citrate.

An abnormal urine composition is a key reason for kidney stone formation, but little is known about the roles of small metabolites in the urine during kidney stone formation. Here, we found urine glycine in patients with kidney calcium oxalate (CaOx) stone was significantly lower than that in healthy people via 1 H NMR spectra detection, and investigated the role and underlying mechanism of glycine in the regulation of CaOx stone formation. Our results showed that glycine could significantly attenuate ethylene glycol-induced CaOx crystal depositions in rat kidney via decreasing urine oxalate and increasing urine citrate. Mechanism studies revealed that glycine could decrease urine oxalate through downregulating Slc26a6 expression, whereas increase urine citrate via inhibiting Nadc1 expression. Moreover, glycine decreased the protein expression of both Slc26a6 and Nadc1 via increasing the expression of miRNA-411-3p, which directly bound to the 3'-untranslated regions of Slc26a6 and Nadc1 messenger RNAs, in vitro and in vivo. Together, our results revealed a novel role of glycine in the regulation of kidney CaOx crystal formation and provided a potential target for the treatment of kidney CaOx stone.

Linking 24-h urines to clinical phenotypes: what alternatives does the future bring?

PURPOSE OF REVIEW: The 24-h urine test is recommended as part of the metabolic evaluation for patients with nephrolithiasis to guide preventive interventions. However, this test may be challenging to interpret and has limits in its predictive ability. In this review, we summarize and discuss the most recent research on the opportunities and challenges for utilizing urinary biomarkers for kidney stone prevention. RECENT FINDINGS: Contemporary studies utilizing the 24-h urine test have improved our understanding of how to better administer testing and interpret test results. Beyond the standard panel of 24-h urine parameters, recent applications of proteomics and metabolomics have identified protein and metabolic profiles of stone formers. These profiles can be assayed in future studies as potential biomarkers for risk stratification and prediction. Broad collaborative efforts to create large datasets and biobanks from kidney stone formers will be invaluable for kidney stone research. SUMMARY: Recent advances in our understanding of kidney stone risk have opened opportunities to improve metabolic testing for kidney stone formers. These strategies do not appear to be mutually exclusive of 24-h urine testing but instead complementary in their approach. Finally, large clinical datasets hold promise to be leveraged to identify new avenues for stone prevention.

Immunotherapy for stone disease.

PURPOSE OF REVIEW: In addition to traditional risk factors such as low urine volume or hypercalciuria, emerging data suggest that calcium oxalate (CaOx), one of the most common mineral complexes in the urine, elicits a strong immunologic response. This review highlights those studies and projects how future therapies may be directed for kidney stone prevention. RECENT FINDINGS: Over the last 2 years, several groups have studied the response of the immune system to CaOx crystals using cell culture and animal models. Dominguez et al. found that CaOx crystals were recognized by monocytes through an lipopolysaccharide-mediated mechanism, leading to M1 'inflammatory' macrophage phenotype. Patel et al. proposed excessive oxalate-mediated reactive oxygen species within macrophage mitochondria may impair their ability to properly clear stones. Two other groups developed mouse models (an androgen receptor knock-out and an overexpression of Sirtuin 3 protein) and demonstrated increased renal anti-inflammatory macrophage differentiation and decreased CaOx deposition in experimental compared with controls. Anders et al. fed hyperoxaluric mice 1,3-butanediol, which blocks an inflammatory form of cell death called NLRP3 inflammasome and found less intrarenal oxidative damage and higher anti-inflammatory renal infiltrates in experimentals. Finally, monocytes exposed to CaOx crystals followed by hydroxyapatite had reduced inflammatory cytokine and chemokine production compared with those without hydroxyapatite, suggesting that Randall's plaque may play a role in dampening M1-mediatiated CaOx inflammation. SUMMARY: By modulating the immune response, immunotherapy could provide the means to prevent stone recurrences in certain individuals. The promotion of M2 over M1 macrophages and inhibition of inflammation could prevent the cascade that leads to CaOx nucleation. Future therapies may target the ability of macrophages to degrade CaOx crystals to prevent stones.

Prevention of recurrent urinary stone disease.

PURPOSE OF REVIEW: Urinary stone disease (USD) is increasing in prevalence and recurrence is common. In pediatrics, most stones are composed primarily of calcium with the highest incidence observed in adolescents. Given the morbidity associated with USD, an in depth review of current management strategies is of paramount importance to highlight the data supporting the recommended treatments and the knowledge gaps which still exist. RECENT FINDINGS: Several interventions for the management of recurrent calcium USD in children have been recommended based on primarily adult studies. These interventions include modification of diet and fluid intake in addition to the utilization of medications such as thiazide diuretics and citrates when supportive care is inadequate. Overall there is conflicting data in the adult literature which is further complicated by our attempts to extrapolate these data to children. SUMMARY: Based on the currently available literature the management of USD in pediatrics should be individualized to each patient and focused on the particular metabolic risk factors that are identified during the course of their evaluation. Several interventions may be required or trialed in a particular patient to show an effect. Well designed trials to assess the efficacy of each intervention in the pediatric population are needed.

Dietary and lifestyle factors for primary prevention of nephrolithiasis: a systematic review and meta-analysis.

BACKGROUND: Dietary and lifestyle factors may play an important role in the increasing prevalence of nephrolithiasis. We aimed to review and quantify the associations between lifestyle factors and incident nephrolithiasis and suggest lifestyle changes for the primary prevention of nephrolithiasis. METHODS: PubMed, EMBASE, and Cochrane Library were searched up to May 2019, for observational studies and randomized controlled trials (RCTs) that assessed modifiable lifestyle factors and risk of nephrolithiasis in adults. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were computed using a random effects model. The I2 statistic was employed to evaluate heterogeneity. Subgroup analysis, sensitivity analysis and meta-regression were also conducted whenever possible. RESULTS: Fifty relevant articles with 1,322,133 participants and 21,030 cases in total were identified. Prominent risk factors for incident stones were body mass index (1.39,1.27-1.52), dietary sodium (1.38, 1.21-1.56), fructose, meat, animal protein, and soda. In contrast, protective factors included fluid intake (0.55, 0.51-0.60), a Dietary Approaches to Stop Hypertension (DASH) style diet (0.69, 0.64-0.75), alcohol (0.69, 0.56-0.85), water, coffee, tea, vegetables, fruits, dietary fiber, dietary calcium (0.83, 0.76-0.90), and potassium. Vitamin D (1.22, 1.01-1.49) and calcium (1.16, 1.00-1.35) supplementation alone increased the risk of stones in meta-analyses of observational studies, but not in RCTs, where the cosupplementation conferred significant risk. CONCLUSIONS: Several modifiable factors, notably fluid intake, dietary patterns, and obesity, were significantly associated with nephrolithiasis. Long-term RCTs are required to investigate the cost-effectiveness of dietary patterns for stone prevention. The independent and combined effects of vitamin D and calcium supplementation on nephrolithiasis need further elucidation.

Fu-Fang-Jin-Qian-Cao herbal granules protect against the calcium oxalate-induced renal EMT by inhibiting the TGF-ß/smad pathway.

CONTEXT: Nephrolithiasis is a major public health problem worldwide and Fu-Fang-Jin-Qian-Cao granules (FFJQC) is a traditional Chinese herbal formula that is used to treat nephrolithiasis. The main component of nephrolithiasis is calcium oxalate (CaOx) and the epithelial-mesenchymal transition (EMT) shown to play a crucial role in CaOx-induced kidney injury. However, the mechanism underlying the therapeutic effect of FFJQC on the CaOx-induced renal EMT is unknown. OBJECTIVE: This study explores the therapeutic benefits and mechanism of FFJQC in oxalate-induced kidney injury. MATERIALS AND METHODS: 60 male C57BL/6 mice were used in this experiment and divided into 6 groups. A mouse kidney stone model was created by intraperitoneal injection of glyoxylate at a dose of 100 mg/kg for 6 days. The standardized FFJQC was used to treat mouse crystal kidney injury by gavage at 1.35 and 2.7 g/kg, respectively. Western blotting and immunostaining for E-cadherin, cytokeratin 18 (CK18), vimentin, smooth muscle α-actin (α-SMA) and transforming growth factor ß (TGF-ß)/Smad pathway were conducted on renal tissues. RESULTS: Following CaOx-induced kidney injury, the levels of E-cadherin and CK18 in kidney decreased, while vimentin and α-SMA levels increased. The FFJQC treatment increased the levels of E-cadherin and CK18 and decreased vimentin and α-SMA levels in varying degrees. What's more, the FFJQC reduced the expression of CaOx-induced fibrosis marker collagen II. CONCLUSION: FFJQC alleviated the CaOx-induced renal EMT and fibrosis by regulating TGF-ß/smad pathway. Therefore, the FFJQC is an important traditional Chinese medicine for the treatment of CaOx-induced renal injury and fibrosis.

Perceptions of dietary factors promoting and preventing nephrolithiasis: a cross-sectional survey.

OBJECTIVE: To assess knowledge of both promoting and preventive dietary factors on nephrolithiasis in a diverse patient population. Precipitating factors of kidney stone disease include diet, lifestyle, socioeconomic status, and race/ethnicity. However, patient awareness of these influences is poorly described. MATERIALS AND METHODS: A 24-question survey, assessing intake-related risk factors for stone disease, was administered prospectively to 1018 patients. Responses were summarized with frequency and percent. Statistical comparisons were made using a propensity scoring method in order to account for potential confounding variables. Propensity scores were stratified into quintiles. Further analysis with multiple imputation was performed to account for any missing data in the survey. The results of the propensity-adjusted log-binomial regression model are presented as prevalence ratios (PRs) and 95% confidence intervals (CIs). RESULTS: Respondents demonstrated limited knowledge of nutrient factors that influence stone development. However, most study participants (70.3%) reported a willingness to make lifestyle changes aimed at lowering their risk for stone disease. Respondents reporting previous nephrolithiasis education were less likely to report that diet had no effect on kidney stone formation (PR = 0.795, 95% CI 0.65, 0.96, p = 0.01) The type of physician who counseled the respondent had no association with patient knowledge for stone disease (PR = 0.83, 95% CI 0.63, 1.10, p = 0.2). CONCLUSIONS: Knowledge of diet-related risk factors for nephrolithiasis is limited among this population. Respondents who received prior education appeared to maintain the knowledge of dietary risk for nephrolithiasis. Participants also expressed a willingness to make requisite dietary changes if that information is provided. Given that most stone formers experience a recurrence, these findings highlight the need for more comprehensive patient education strategies on the modifiable risk factors for nephrolithiasis.

Vitamin K1 Inhibition of Renal Crystal Formation through Matrix Gla Protein in the Kidney.

BACKGROUND AND OBJECTIVES: Vitamin K (VK) plays a major role in modifying the binding of calcium in bones and blood vessels. Understanding the effect of VK on crystal formation in the kidney would contribute to advancing the treatment and prevention of kidney stones. METHODS: Rats were treated with vitamin K1 (VK1) for 8 weeks. VK1 levels were detected and crystal formation were observed. HK2 cells were exposed to calcium oxalate monohydrate crystals. Apoptosis and cell viability were detected. Crystal deposition was analyzed using atomic absorption assay. The adenovirus vectors expressing matrix Gla protein (MGP) and siMGP were constructed to elucidate the effect and mechanism of VK1 on crystal formation. MGP expression in vivo and in vitro was analyzed by Western blot. The mRNA levels of monocyte chemoattractant protein-1 (MCP-1) and collagen I was measured by semiquantitative RT-PCR. RESULTS: The concentrations of VK1 in whole blood and kidney tissues rose under treatment with VK1. Crystal formation was inhibited from the second to the 6th week, the frequency and quality of crystal formation decreased significantly, and the location of crystal formation was limited to a greater extent in the rats treated by VK1 compared to the control group. Warfarin treatment in the crystals-exposed HK2 cells significantly increased the number of crystals adhering to cells and the number of apoptotic cells and reduced cell viability. VK1 treatment reversed warfarin's above influence. VK1 inhibited the upregulations of MCP-1 and collagen I in kidney tissues under crystal load. VK1 treatment increased MGP expression in vivo and in vitro, and MGP is necessary for VK1 to play a role in crystal deposition in cells. CONCLUSIONS: VK1 treatment can inhibit the formation of renal crystals in vivo. VK1 increases MGP expression and functions through MGP to reduce crystal deposition in cells and provide cell protection. Our findings suggest that VK1 treatment could be a potential strategy for the treatment and prevention of nephrolithiasis.

Risk Factors for Nephrolithiasis in Adults with Short Bowel Syndrome.

INTRODUCTION: Patients with short bowel syndrome (SBS) commonly develop nephrolithiasis. However, the risk factors for nephrolithiasis in patients with SBS remain unclarified. The present study aimed to identify the risk factors for nephrolithiasis in adults with SBS. METHODS: All eligible adults diagnosed with SBS and admitted to a tertiary referral center from December 2008 to 2018 were retrospectively identified from a prospectively maintained database. Patients' demographic and clinical characteristics were analyzed using univariate and multivariate analyses to identify the risk factors for nephrolithiasis. RESULTS: Of 231 adults with SBS, 42 (18.2%) developed nephrolithiasis. The mean age was 46.4 ± 17.8 years, the mean body mass index was 18.2 ± 3.8 kg/m2, and median duration of SBS was 11 months (range 2-324 months). Multivariate binary logistic regression analysis revealed that the independent risk factors for nephrolithiasis in adults with SBS were jejuno-ileal anastomosis and colon-in-continuity (OR 4.335; 95% CI 1.175-16.002; p = 0.028), prolonged duration of SBS (OR 1.008; 95% CI 1.002-1.014; p = 0.010), and increased serum creatinine concentration (OR 1.005; 95% CI 1.001-1.009; p = 0.012). CONCLUSIONS: Nephrolithiasis is common in adults with SBS. As nephrolithiasis can have adverse clinical consequences, patients with SBS should be closely monitored, and prophylactic interventions should be considered.

Is it Safe to Reduce Water Intake in the Overactive Bladder Population? A Systematic Review.

PURPOSE: Overactive bladder imposes a significant socioeconomic burden on the health care system. It is a commonly held belief that increased fluid intake (8 glasses of water per day) is beneficial for health. However, increased fluid intake exacerbates overactive bladder symptoms. Thus, it is imperative that clinicians appropriately educate patients for whom increased water intake may be detrimental (women with overactive bladder), in contrast to patients with comorbidities that necessitate increased water intake (nephrolithiasis). We systematically reviewed the literature to determine the potential health advantages of increased water intake and identify specific subpopulations that need increased hydration. MATERIALS AND METHODS: We systematically reviewed published articles from 1972 through 2017 on PubMed® and the Cochrane Library. The data were reviewed independently by 2 individuals. Studies were included if they explored water intake in relation to the risk of a particular disease. RESULTS: Level 1 evidence supported increased fluid intake in patients with nephrolithiasis. There was no available evidence to support increased fluid intake in patients with cardiovascular disease, constipation, venous thromboembolism, headaches, cognitive function or bladder cancer. Dehydration may exacerbate some conditions, specifically chronic constipation and headache intensity. Increased fluid intake may have a role in preventing stroke recurrence but not in preventing primary stroke. CONCLUSIONS: The available reviewed literature suggests no benefit to drinking 8 glasses of water per day in patients without nephrolithiasis. Also, excess fluid intake can exacerbate symptoms of overactive bladder.

Pediatric calculi: cause, prevention and medical management.

PURPOSE OF REVIEW: The incidence of pediatric nephrolithiasis is on the rise, with a significant related morbidity and a concomitant relevant increase in healthcare costs. The purpose of this review is to portray the current epidemiology and cause of renal stones in children, to provide a framework for appropriate clinical evaluation on an individual basis, and a guidance regarding treatment and prevention for the significant risk of lifelong recurrence and deriving complications. RECENT FINDINGS: The early identification of modifiable risk factors and other abnormalities is essential, to prevent related morbidity, the onset of chronic kidney disease, and the associated increased risk of developing other diseases. The implementation of risk reduction strategies, including dietary modifications and targeted pharmacological therapies, will significantly influence stone recurrences and preserve renal function. SUMMARY: Future research is desirable, with the aim to strengthen personalized conservative management of pediatric nephrolithiasis as first-line treatment.

Nephrolithiasis: A complication of pediatric diabetic ketoacidosis.

OBJECTIVE: To determine the frequency of nephrolithiasis as a complication of diabetic ketoacidosis (DKA) in pediatrics. METHODS: We performed a retrospective chart review of patients with DKA admitted to a pediatric hospital between January 2009 and July 2016. We identified patients with nephrolithiasis during admission for DKA. RESULTS: We identified 395 episodes of DKA over 7.5 years. Nephrolithiasis developed as a complication of DKA in 3 of those admissions (0.8%). All three patients with nephrolithiasis were males with new onset type 1 diabetes, aged 11 to 16.5 years. They all developed symptoms of nephrolithiasis after transition to subcutaneous insulin. One patient had subsequent worsening acidosis that required an additional 24 hours of IV insulin administration. CONCLUSIONS: Nephrolithiasis is a rare complication of pediatric DKA, and should be considered in children with DKA who develop hematuria, flank pain, or suprapubic pain. Nephrolithiasis can increase insulin resistance due to increased pain and inflammation, so these patients should be monitored closely for recurrence of DKA. As patients with diabetes have increased risk of chronic kidney disease and nephrolithiasis can cause kidney injury, risk factors for nephrolithiasis should be identified and addressed to avoid subsequent kidney damage.

Role of gut microbiota against calcium oxalate.

Nephrolithiasis is a condition marked by the presence or formation of stones in kidneys. Several factors contribute to kidney stones development such as environmental conditions, type of dietary intake, gender and gastrointestinal flora. Most of the kidney stones are composed of calcium phosphate and calcium oxalate, which enter in to the body through diet. Both sources of oxalates become dangerous when normal flora of gastrointestinal tract is disturbed. Oxalobacter and Lactobacillus species exist symbiotically in the human gut and prevent stone formation by altering some biochemical pathways through production of specific enzymes which help in the degradation of oxalate salts. Both Oxalobacter and Lactobacillus have potential probiotic characteristics for the prevention of kidney stone formation and this avenue should be further explored.

Water and other fluids in nephrolithiasis: State of the art and future challenges.

Adequate hydration, as to maintain urinary volume over 2 L/day, has long been considered as the cornerstone medical prescription for preventing nephrolithiasis. However, scientific evidence about what kind of water stone formers should drink and about the effects of other beverages on urinary stone risk factors is sometimes unclear. Moreover, the recommendation that water therapy prevents kidney stone recurrence relies on only one randomized controlled trial, even if more epidemiologic and basic science studies seem to support this assumption. Therefore, in this review we analyze current evidence that support water therapy in nephrolithiasis and we highlight the possible effects of different types of water and other beverages on lithogenic risk, giving some practical recommendations for what stone formers should be advised to prevent recurrence.

Prevention of complications in glycogen storage disease type Ia with optimization of metabolic control.

Prior to 1971, type Ia glycogen storage disease was marked by life-threatening hypoglycemia, lactic acidosis, severe failure to thrive, and developmental delay. With the introduction of continuous feeds in the 1970s and cornstarch in the 1980s, the prognosis improved, but complications almost universally developed. Changes in the management of type Ia glycogen storage disease have resulted in improved metabolic control, and this manuscript reviews the increasing evidence that complications can be delayed or prevented with optimal metabolic control as previously was seen in diabetes.

Inhibitory effect of an aqueous extract of Radix Paeoniae Alba on calcium oxalate nephrolithiasis in a rat model.

OBJECTIVE: To examine the effect of an aqueous extract of Radix Paeoniae Alba (RPA) on the formation of calcium oxalate (CaOx) stones and the potential mechanism underlying the effect. MATERIALS AND METHODS: An in vitro assay was used to determine whether the RPA extract prevents the formation of CaOx or promotes CaOx dissolution. We also investigated the efficacy of the extract in vivo as a preventive and therapeutic agent for experimentally induced CaOx nephrolithiasis in rats. Various biochemical, molecular, and histological parameters were assessed in kidney tissue and urine at the end of the in vivo experiment. RESULTS: Significant dissolution of formed crystals (8.99 ± 1.43) and inhibition of crystal formation (2.55 ± 0.21) were observed in vitro after treatment with 64 mg/mL of the RPA extract compared with a control treatment (55.10 ± 4.98 and 54.57 ± 5.84, respectively) (p < .05). In preventive protocols, the RPA extract significantly reduced urinary and renal oxalate levels and increased urinary calcium and citrate levels compared to the control. In addition, the RPA preventive protocol significantly decreased osteopontin expression, renal crystallization, and pathological changes compared to the control. These changes were not observed in rats on the therapeutic protocol. CONCLUSIONS: RPA is a useful agent that prevents the formation of CaOx kidney stones.

Prediction of renal crystalline size distributions in space using a PBE analytic model. 2. Effect of dietary countermeasures.

An analytic Population Balance Equation model is used to assess the efficacy of citrate, pyrophosphate, and augmented fluid intake as dietary countermeasures aimed at reducing the risk of renal stone formation for astronauts. The model uses the measured biochemical profile of the astronauts as input and predicts the steady-state size distribution of the nucleating, growing, and agglomerating renal calculi subject to biochemical changes brought about by administration of these dietary countermeasures. Numerical predictions indicate that an increase in citrate levels beyond its average normal ground-based urinary values is beneficial but only to a limited extent. Unfortunately, results also indicate that any decline in the citrate levels during space travel below its normal urinary values on Earth can easily move the astronaut into the stone-forming risk category. Pyrophosphate is found to be an effective inhibitor since numerical predictions indicate that even at quite small urinary concentrations, it has the potential of shifting the maximum crystal aggregate size to a much smaller and plausibly safer range. Finally, our numerical results predict a decline in urinary volume below 1.5 liters/day can act as a dangerous promoter of renal stone development in microgravity while urinary volume levels of 2.5-3 liters/day can serve as effective space countermeasures.

Salt and nephrolithiasis.

Dietary sodium chloride intake is nowadays globally known as one of the major threats for cardiovascular health. However, there is also important evidence that it may influence idiopathic calcium nephrolithiasis onset and recurrence. Higher salt intake has been associated with hypercalciuria and hypocitraturia, which are major risk factors for calcium stone formation. Dietary salt restriction can be an effective means for secondary prevention of nephrolithiasis as well. Thus in this paper, we review the complex relationship between salt and nephrolithiasis, pointing out the difference between dietary sodium and salt intake and the best methods to assess them, highlighting the main findings of epidemiologic, laboratory and intervention studies and focusing on open issues such as the role of dietary salt in secondary causes of nephrolithiasis.