Calcium Kidney Stones Research Articles

METABOLIC ALKALEMIA IN HYPERCALCIURIA STONE FORMERS: DOES IT MATTER?

We collected clinical, demographic characteristics, and laboratory data from electronical medical charts of outpatients with calcium-kidney stones followed in our institution from January 2013 to July 2021. We diagnosed as metabolic alkalemia those cases in which the venous blood gas tests showed pH≥7.46 and bicarbonate concentration>26 mEq/L. Then, we applied statistical analysis to compare distinct categories between patients with and without metabolic alkalemia. We diagnosed metabolic alkalemia in 4.3% of hypercalciuric nephrolithiasis outpatients, and we verified that thiazides had been used in all of them except in one case. Furthermore, we observed that the amount of thiazide taken daily was higher in patients with metabolic alkalemia than those without this imbalance. Additionally, hypokalemia was present in 37% of patients that developed metabolic alkalemia. We also found lower chloride, magnesium and ionic calcium serum concentrations in patients with metabolic alkalemia than in those without an acid-base disequilibrium. Despite the low prevalence of metabolic alkalemia in hypercalciuric kidney stone formers, it is important to monitor these patients due to high incidence of hypokalemia and the potential presence of other electrolyte disorders.

Insulin Resistance in Hypercalciuric Calcium Kidney Stone Patients

Rational and ObjectiveDiabetes and uric acid kidney stones are strongly associated. Patients with calcium kidney stones also have higher risk of developing diabetes compared to non-kidney stone patients yet this has not been further investigated. We aimed to characterize insulin resistance in calcium kidney stone patients. Study DesignObservational Setting & PopulationThis study was performed in the University of Chicago Clinical Research Center. Kidney stone patients (N=42) were selected for having idiopathic hypercalciuria and calcium stones with no other medical conditions and controls (N=27) were healthy. ExposuresAll participants presented to the Clinical Research Center in a fasting state and at least 2 timed fasting blood and urine were collected prior to a fixed breakfast. Six additional timed blood and urine collections were performed after breakfast. OutcomesWe compared fasting and fed indices of insulin resistance between the groups. Analytic ApproachWe used t-tests and multivariable linear regression models. A sensitivity analysis removing all patients who had ever been on a thiazide diuretic was also performed. ResultsIn separate multivariable linear models, kidney stone patients had higher fasting serum insulin (24 (3 to 46pmol/L), p=0.03) and higher homeostatic model of insulin resistance (HOMA-IR) (1.0 (0.2 to 1.8), p=0.02). In separate multivariable linear models, kidney stone patients had higher fed serum glucose (10 (2 to 18mg/dL), p=0.01). Results were similar in a sensitivity analysis removing all patients who had ever been on a thiazide diuretic. There were no differences in urine composition based on HOMA-IR levels. LimitationsSingle institution. Small sample size limited subanalyses by different calcium stone types. ConclusionsCalcium kidney stone patients without diabetes or other medical conditions demonstrated signs of insulin resistance compared to healthy matched controls.

Комплексное средство для метафилактики кальций-оксалатного нефролитиаза.

Introduction. In the structure of urolithiasis, the predominant number of patients have stones consisting of calcium oxalate. These stones have a dense structure that is not amenable to litholysis and grows quickly. At the moment, there are no medications that can non-invasively relieve patients of this type of stones. In this connection, the main methods of treatment, depending on the size of the stones, are either lithokinetic therapy or surgical treatment. However, stone removal does not eliminate the cause of stone formation, and with this approach, relapse of the disease occurs within 5 years in 30-50% of patients. Today, the search for new approaches and means to reduce the risk of recurrence of calcium oxalate stones does not stop. One of these products is a representative of the Lit-Сontrol® Litura® line from Devicare (Spain) – Litura® Balance. The purpose of this publication is to theoretically substantiate the potential clinical effects of Litura® Balance in the metaphylaxis of calcium oxalate stones. Materials and methods. A literature search and analysis of foreign and domestic literature was carried out using the databases SCOPUS/ScienceDirect, PubMed/MEDLINE, eLibrary, Google Scholar, from 1990 to 2024 using keywords – the active components of Lit-Control® pH Balance – phytate, phytic acid, magnesium and polyphenols, vitamin A, zinc. References in included sources were reviewed to identify additional potentially relevant studies. 167 sources were found, based on relevance, of which 52 articles were selected. Results. The use of Litura® Balance has a scientific basis, and the included substances and their combination potentiate the clinical effect in the metaphylaxis of calcium oxalate stones. However, controlled clinical studies are necessary to assess the prospects for using these complex agents. Conclusions. The results of international experimental and clinical studies allow us to conclude that the complex product Litura® Balance, used to inhibit the processes of calcium oxalate crystallization and antioxidant protection of the urothelium, can be considered as a new promising approach to the metaphylaxis of calcium kidney stones.

Association between Kidney Stones and CKD: A Bidirectional Mendelian Randomization Study.

Kidney stones and CKD are common disorders with a substantial interaction. Although observational studies have suggested a potential for enhanced CKD risk after prior kidney stones, the exact relationship remains ambiguous. Shared comorbidities between two diseases were identified using unbiased screening. Genome-wide association study summary statistics were obtained from the UK Biobank (UKBB), FinnGen, and CKDGen, followed by genetic association analyses across various traits. Bidirectional Mendelian randomization (MR) analyses were performed to define causal links, complemented by multivariable MR that included the shared comorbidities including hypertension, diabetes, and obesity. Observational analyses were undertaken using cohorts from the Mayo Clinic and a UKBB subset. Despite identifying a total of 123 conditions as shared comorbidities, there was no significant genetic correlation between kidney stones and CKD. Unadjusted MR analysis revealed no significant association between kidney stones and CKD risk (UKBB [exposure]/FinnGen [outcome]: OR=0.97, 95% CI: 0.88∼1.06; FinnGen/UKBB: OR=1.17, 95% CI:0.98∼1.39). Kidney stones did significantly associate with a higher urinary albumin-creatinine ratio (UACR) (β=0.014, 95% CI: 0.002∼0.025), but this association disappeared in the multivariable MR model (β=0.009, 95% CI: -0.003∼0.020). Furthermore, in a cross-sectional analysis limited to the UKBB cohort, a robust regression model did not detect an independent association between kidney stones and UACR (β=0.16, 95% CI: -0.04∼0.35) or eGFR (β=0.10, 95% CI: -0.07∼0.28). Conversely, CKD associated with a diminished risk of kidney stones in multivariable MR models (UKBB/FinnGen: OR=0.77, 95% CI: 0.69∼0.87; FinnGen/UKBB: OR=0.73, 95% CI: 0.66∼0.81). Furthermore, in the Mayo Clinic cohort with available urinary biochemistries, lower eGFR was associated with lower urinary calcium excretion and urinary calcium oxalate/phosphate supersaturation. In this study, kidney stones were not independently associated with CKD. Conversely, CKD was associated with a lower risk of calcium kidney stones likely via changes in key urinary traits, including lower calcium excretion.

The Rise in Tubular pH during Hypercalciuria Exacerbates Calcium Stone Formation.

In calcium nephrolithiasis (CaNL), most calcium kidney stones are identified as calcium oxalate (CaOx) with variable amounts of calcium phosphate (CaP), where CaP is found as the core component. The nucleation of CaP could be the first step of CaP+CaOx (mixed) stone formation. High urinary supersaturation of CaP due to hypercalciuria and an elevated urine pH have been described as the two main factors in the nucleation of CaP crystals. Our previous in vivo findings (in mice) show that transient receptor potential canonical type 3 (TRPC3)-mediated Ca2+ entry triggers a transepithelial Ca2+ flux to regulate proximal tubular (PT) luminal [Ca2+], and TRPC3-knockout (KO; -/-) mice exhibited moderate hypercalciuria and microcrystal formation at the loop of Henle (LOH). Therefore, we utilized TRPC3 KO mice and exposed them to both hypercalciuric [2% calcium gluconate (CaG) treatment] and alkalineuric conditions [0.08% acetazolamide (ACZ) treatment] to generate a CaNL phenotype. Our results revealed a significant CaP and mixed crystal formation in those treated KO mice (KOT) compared to their WT counterparts (WTT). Importantly, prolonged exposure to CaG and ACZ resulted in a further increase in crystal size for both treated groups (WTT and KOT), but the KOT mice crystal sizes were markedly larger. Moreover, kidney tissue sections of the KOT mice displayed a greater CaP and mixed microcrystal formation than the kidney sections of the WTT group, specifically in the outer and inner medullary and calyceal region; thus, a higher degree of calcifications and mixed calcium lithiasis in the kidneys of the KOT group was displayed. In our effort to find the Ca2+ signaling pathophysiology of PT cells, we found that PT cells from both treated groups (WTT and KOT) elicited a larger Ca2+ entry compared to the WT counterparts because of significant inhibition by the store-operated Ca2+ entry (SOCE) inhibitor, Pyr6. In the presence of both SOCE (Pyr6) and ROCE (receptor-operated Ca2+ entry) inhibitors (Pyr10), Ca2+ entry by WTT cells was moderately inhibited, suggesting that the Ca2+ and pH levels exerted sensitivity changes in response to ROCE and SOCE. An assessment of the gene expression profiles in the PT cells of WTT and KOT mice revealed a safeguarding effect of TRPC3 against detrimental processes (calcification, fibrosis, inflammation, and apoptosis) in the presence of higher pH and hypercalciuric conditions in mice. Together, these findings show that compromise in both the ROCE and SOCE mechanisms in the absence of TRPC3 under hypercalciuric plus higher tubular pH conditions results in higher CaP and mixed crystal formation and that TRPC3 is protective against those adverse effects.

Safety and efficacy of a polyherbal formulation from traditional Persian medicine in patients with calcium kidney stones: A randomized, double-blinded clinical trial.

10%-15% of the world's population suffers from kidney stones. Nearly 50% increase was observed in diagnosing and treating nephrolithiasis in the last decades. Effective medical treatment for the disease is not yet well established. Moreover, there is an increasing global demand to manage diseases using complementary and alternative medicine. This study aimed to formulate and assess the safety and efficacy of a multi-ingredient formulation from traditional Persian medicine (TPM) known as Mofatet powder in patients suffering from calcium kidney stones. The aqueous extract of Mofatet powder was prepared, freeze-dried, and formulated as capsules. 26 patients in the drug group and 25 patients in the placebo group used 500 mg capsules of the drug/placebo twice daily for 5 weeks. Ultrasonography/kidney, ureter and bladder imaging, urine analysis, and biochemical parameters were evaluated before and after the intervention. The imaging results showed a 60.73% decrease (P < 0.001) in stone size in the drug group. Moreover, the urinary calcium decreased (P = 0.02) and the urinary magnesium increased (P < 0.001) in the drug group. No remarkable changes were observed in the placebo group in these parameters. No significant effect was observed in aspartate transaminase, alanine transaminase, serum creatinine, and blood urea nitrogen levels in none of the groups. This study suggests that Mofatet powder was effective in reducing calcium kidney stones size with no potential nephro/hepatotoxicity. After confirming these results in larger clinical trials with longer duration, this formulation can be considered a treatment for nephrolithiasis.

The Optimal Length of Pharmacological Prophylaxis in Calcium Kidney Stone Formers.

The Optimal Length of Pharmacological Prophylaxis in Calcium Kidney Stone Formers.

Effect of two vitamin D repletion protocols on 24-h urine calcium in patients with recurrent calcium kidney stones and vitamin D deficiency: a randomized clinical trial

ObjectivesTo evaluate the effects of two vitamin D repletion therapies (cholecalciferol) on serum levels of 25-hydroxyvitamin D (25(OH)D) and 24-h urine calcium in patients with recurrent calcium kidney stones and vitamin D deficiency (VDD).Design, setting, participantsA parallel-group randomized controlled clinical trial on patients who referred to Labbafinejad kidney stone prevention clinic, Tehran, Iran. From 88 recurrent calcium stone formers, 62 patients completed the study. The age of participants was 18–70 years who had serum 25(OH)D levels of 10–20 ng/ml.InterventionParticipants received oral cholecalciferol 2000 IU daily for 12 weeks or 50,000 IU weekly for 8 weeks.Main outcome measuresStudy variables including 24-h urine calcium, supersaturations of calcium oxalate and calcium phosphate, serum 25(OH)D and parathyroid hormone were measured at the beginning of the study and after 12 weeks.ResultsThe 24-h urine calcium significantly increased in both groups (β = 69.70, p < 0.001), with no significant difference between treatments. Both groups showed no significant change in the supersaturation levels of calcium oxalate and calcium phosphate. Serum levels of 25(OH)D increased significantly (β = 12.53, p < 0.001), with more increase in the 50,000 IU group (β = 3.46, p = 0.003). Serum parathyroid hormone decreased in both groups (p < 0.001).ConclusionsAlthough both treatment protocols increased 24-h urine calcium, they did not increase the supersaturation state of calcium oxalate or calcium phosphate.Trial registration IRCT20160206026406N4, 13/08/2019.

Effect of a high-citrate beverage on urine chemistry in patients with calcium kidney stones.

A well-accepted strategy to prevent kidney stones is to increase urine volume by increasing oral intake of fluids, especially water, to lower supersaturation of the relevant, relatively insoluble salts, and thereby lower the risk of precipitation. Randomized controlled trials have shown that this strategy works. It is inexpensive, safe, and intuitively attractive to patients. However, although any beverage can increase urine volume, and citrus juices can increase urine citrate content and pH, no beverage other than water has been clearly shown by randomized controlled trial to prevent kidney stones. We designed an innovative, palatable, low-calorie, high alkali citrate beverage to prevent kidney stones, called Moonstone. One packet of Moonstone powder, mixed in 500ml of water, contains 24.5meq of alkali citrate. We administered one packet twice a day to ten calcium stone formers. Moonstone resulted in an increase in mean 24-h urine citrate and urine pH, and a decrease in supersaturation of calcium oxalate in calcium stone formers compared to an equal volume of water. These changes, comparable to those seen in a prior study of a similar amount of (potassium-magnesium) citrate, will likely be associated with a clinically meaningful reduction in kidney stone burden in patients with calcium stones. The effect to increase urine pH would also be expected to benefit patients with uric acid and cystine stones, groups that we hope to study in a subsequent study. The study preparation was well tolerated and was selected as a preferred preventative strategy by about half the participants. Moonstone is an alternative, over-the-counter therapy for kidney stone prevention.

Nephrolithiasis and Multicystic Kidneys in a Young Patient: A Quiz

Nephrolithiasis and Multicystic Kidneys in a Young Patient: A Quiz

MP05-17 RISKS OF CAROTID ARTERY STENOSIS AND ATHEROSCLEROTIC CARDIOVASCULAR DISEASE IN PATIENTS WITH CALCIUM KIDNEY STONE: ASSESSMENT OF SYSTEMIC INFLAMMATORY BIOMARKERS

You have accessJournal of UrologyCME1 Apr 2023MP05-17 RISKS OF CAROTID ARTERY STENOSIS AND ATHEROSCLEROTIC CARDIOVASCULAR DISEASE IN PATIENTS WITH CALCIUM KIDNEY STONE: ASSESSMENT OF SYSTEMIC INFLAMMATORY BIOMARKERS Chang Te Wang, Chan Jung Liu, Hau Chern Jan, and Ho Shiang Huang Chang Te WangChang Te Wang More articles by this author , Chan Jung LiuChan Jung Liu More articles by this author , Hau Chern JanHau Chern Jan More articles by this author , and Ho Shiang HuangHo Shiang Huang More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003216.17AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To assess the clinical significance of preoperative inflammatory biomarkers combined with atherosclerotic cardiovascular disease (ASCVD) risk score to evaluate carotid artery stenosis in patients with calcium kidney stones. METHODS: We conducted a prospective observational case-control study, enrolling seventy four patients with calcium kidney stones and sixty six age- and sex-matched healthy controls. We calculated the inflammatory biomarkers including the neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), and systemic inflammation response index (SIRI). Ultrasound of the carotid arteries was performed on all participants to identify the severity of the stenosis. RESULTS: All inflammatory biomarkers and the severity of carotid artery stenosis were higher in the calcium kidney stone group than in controls. After stratification of ASCVD, inflammatory biomarkers and carotid artery stenosis severity were still significantly higher in the calcium kidney stone group. Multivariate analyses showed that calcium kidney stones significantly increased the risk of ASCVD and carotid artery stenosis. In multivariate linear logistic regression analyses, calcium kidney stone and ASCVD score had a significant association with carotid artery occlusion, but SIRI did not. CONCLUSIONS: Calcium kidney stone is associated with higher levels of inflammatory biomarkers and carotid artery stenosis. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e50 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Chang Te Wang More articles by this author Chan Jung Liu More articles by this author Hau Chern Jan More articles by this author Ho Shiang Huang More articles by this author Expand All Advertisement PDF downloadLoading ...

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

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

Despite Higher Oxalate Content, Whole Grains Should Be Encouraged in Patients with a History of Calcium Kidney Stones

Despite Higher Oxalate Content, Whole Grains Should Be Encouraged in Patients with a History of Calcium Kidney Stones

Calcium Decay Ability of Extracts Chromolaena odorata L. Leaves (Asteraceae) on Kidney Stones

Background: Kidney stones are one of the causes of chronic and acute kidney failure symptoms. The flavonoid compounds in Chromolaena odorata leave extract are thought to dissolve calcium in kidney stones. Objective: This study aims to determine the activity of Chromolaena odorata leaves extract as a laxative for calcium kidney stones and to characterize the active extract with a liquid chromatograph mass spectrometry. Methods: The leaves of Chromolaena odorata were extracted by ultrasonication method using 3 solvents in stages, namely n-hexane, ethyl acetate, and methanol. The powder for kidney stones was immersed in an extract solution of n-hexane, ethyl acetate, and methanol for 5 hours at 37° C. The reaction results were analyzed for their absorbance using a UV-Vis spectrophotometer. The fraction with the best activity was analyzed for phytochemical content with various typical reagents and LCMS. Results: Methanol extract of Chromolaena odorata has a better effect in dissolving calcium kidney stones. Methanol extract of Chromolaena odorata can reduce calcium in kidney stones with an EC50 value of 16801 µg/mL. Based on phytochemical tests and LCMS analysis, the methanol extract of Chromolaena odorata leaves contains compounds of the tannins, alkaloids, flavonoids, and steroids. Chromatogram at a retention time of 7.76; 8.96; and 10.01 in the methanol extract of Chromolaena odorata identified 3,5,7,4'-tetrahydroxy-8,3'-dimethoxyflavone; 5,7,4’-trihydroxy-3’,5’-dimethoxyflavone, and 5,6,7,8,4'-pentamethoxyflavone compounds. Conclusion: Methanol extract had the best calcium decay activity in kidney stones with an EC50 value of 16801 µg/mL. 3,5,7,4'-tetrahydroxy-8,3'-dimethoxyflavone; 5,7,4’-trihydroxy-3’,5’-dimethoxyflavone, and 5,6,7,8,4'-pentamethoxyflavone compounds are contained in methanol extract which is thought to play a role in shedding calcium in kidney stones.

Effect of diuretics on kidney stone-forming risk – an investigation using multiple timed urine collections

Introduction: Thiazide diuretics can lower urinary calcium excretion, helping to prevent recurrent calcium kidney stones. As dietary intake and urine chemistry varies throughout the day, a 24-h urine collection may not provide sufficient information to guide the optimal management in individual patients. Using multiple timed urine collections, we sought to identify times during the day when stone-forming risk is higher, allowing for therapy to be more accurately targeted. Methods: In a prospective study, healthy adult volunteers took a 4-week course of either hydrochlorothiazide (HCTZ) 25 mg/d or indapamide 2.5 mg/d. They were assessed at baseline, and at days 7, 14 and 28. At each time point, blood samples were taken for analysis and multiple timed urine samples were collected throughout the day, together with one overnight sample. Results: Diuretic treatment was well tolerated. Daily calcium and citrate excretion decreased, while ionized calcium and phosphate excretion were unchanged. Ionized calcium-divalent phosphate and ionized calcium-oxalate products were unchanged. In the timed urine samples, calcium excretion was decreased, particularly by indapamide, in the morning. Indapamide, but not HCTZ, decreased urinary citrate excretion, most obviously in overnight and early morning urines. No changes in ionized calcium were observed. Decreased divalent phosphate excretion was observed at several time points in the indapamide group. The ionized calcium-divalent phosphate product tended to decrease at most time points in both groups but no significant changes were observed in the ionized calcium-oxalate product. Conclusions: Indapamide 2.5 mg/d has a stronger protective effect against forming calcium kidney stones than HCTZ 25 mg/d. Most of the benefits appear to be achieved during the daytime and it may therefore be beneficial to prescribe medication twice daily or in the evening to maximize the protective effects of these agents. The benefits of indapamide treatment were attenuated by a reduction in urinary citrate excretion, an effect which has not been previously described. Keywords: hydrochlorothiazide, indapamide, kidney stones, urine collection

The role of biased calcium-sensing receptor signalling in urinary calcium excretion and kidney stone disease

Michelle Goldsworthy1,2, Asha Bayliss2, Anna Gluck2, Akira Wiberg3, Benjamin Turney1, DominicFurniss3, Rajesh Thakker2, Sarah Howles1,2&#x0D; 1Nuffield Department of Surgical Sciences, University of Oxford, United Kingdom.2Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, UnitedKingdom.3Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Universityof Oxford, United Kingdom.&#x0D; Nephrolithiasis is a major health burden with a poorly understood pathogenesis. We conducteda genome-wide association study in British and Japanese populations identifying twentynephrolithiasis-associated loci. Mutations in the calcium-sensing receptor (CaSR) causedisorders of calcium homeostasis and five identified loci (DGKD, DGKH, WDR72, GPIC1 and BCR)were predicted to influence CaSR-signalling.&#x0D; In a validation population, we demonstrated that genotype at the DGKD-associated locuscorrelated with urinary calcium excretion but not serum calcium concentration. In vitro studiesdemonstrated that knockdown and overexpression of DGKD resulted in biased CaSR-signalling.Thus, treatment of CaSR-expressing HEK cells with DGKD-targeted siRNA (DGKD-KD), resulted indecreased MAPK responses to alterations in extracellular calcium concentration [Ca2+]e, asassessed by SRE-reporter and ERK-phosphorylation (pERK) assays, when compared to cellstreated with scrambled siRNA (WT) but without alteration in intracellular calcium responses[Ca2+]i as assessed by NFAT-reporter and Fluo-4 calcium assays (SRE maximal response DGKD-KD=5.28 fold change vs. WT=7.20 p=0.0065, pERK maximal response DGKD-KD=24.77, vs. WT=39.46 fold change, p=0.0056). Conversely, DGKD overexpression (DGKD-OE) increased MAPKresponses but suppressed [Ca2+]i responses to alterations in [Ca2+]e (SRE maximal responseDGKD-OE =14.13 fold change vs. WT=9.06 fold change, p=0.01; NFAT maximal response DGKDOE=13.67 fold change vs WT=59.16 fold change, p=0.0001).&#x0D; Our results demonstrate that alterations in DGKD expression cause biased CaSR-signalling. Thisbiased signalling may provide an explanation for the correlation of genotype at the DGKDassociatedlocus with urinary calcium excretion but not serum calcium concentration. Ourfindings suggest that biased CaSR-signalling may be a common cause of nephrolithiasis.&#x0D;

The role of biased calcium-sensing receptor signalling in urinary calcium excretion and kidney stone disease

Michelle Goldsworthy1,2, Asha Bayliss2, Anna Gluck2, Akira Wiberg3, Benjamin Turney1, DominicFurniss3, Rajesh Thakker2, Sarah Howles1,2&#x0D; 1Nuffield Department of Surgical Sciences, University of Oxford, United Kingdom.2Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, UnitedKingdom.3Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Universityof Oxford, United Kingdom.&#x0D; &#x0D; Nephrolithiasis is a major health burden with a poorly understood pathogenesis. We conducted a genome-wide association study in British and Japanese populations identifying twenty nephrolithiasis-associated loci. Mutations in the calcium-sensing receptor (CaSR) cause disorders of calcium homeostasis and five identified loci (DGKD, DGKH, WDR72, GPIC1 and BCR) were predicted to influence CaSR-signalling.&#x0D; In a validation population, we demonstrated that genotype at the DGKD-associated locus correlated with urinary calcium excretion but not serum calcium concentration. In vitro studies demonstrated that knockdown and overexpression of DGKD resulted in biased CaSR-signalling. Thus, treatment of CaSR-expressing HEK cells with DGKD-targeted siRNA (DGKD-KD), resulted in decreased MAPK responses to alterations in extracellular calcium concentration [Ca2+]e, as assessed by SRE-reporter and ERK-phosphorylation (pERK) assays, when compared to cells treated with scrambled siRNA (WT) but without alteration in intracellular calcium responses [Ca2+]i as assessed by NFAT-reporter and Fluo-4 calcium assays (SRE maximal response DGKD-KD =5.28 fold change vs. WT=7.20 p=0.0065, pERK maximal response DGKD-KD=24.77, vs. WT= 39.46 fold change, p=0.0056). Conversely, DGKD overexpression (DGKD-OE) increased MAPK responses but suppressed [Ca2+]i responses to alterations in [Ca2+]e (SRE maximal response DGKD-OE =14.13 fold change vs. WT=9.06 fold change, p=0.01; NFAT maximal response DGKD-OE=13.67 fold change vs WT=59.16 fold change, p=0.0001).&#x0D; Our results demonstrate that alterations in DGKD expression cause biased CaSR-signalling. This biased signalling may provide an explanation for the correlation of genotype at the DGKD-associated locus with urinary calcium excretion but not serum calcium concentration. Our findings suggest that biased CaSR-signalling may be a common cause of nephrolithiasis.

Normocalcemic Hyperparathyroidism in Calcium Kidney Stone Formers

Normocalcemic Hyperparathyroidism in Calcium Kidney Stone Formers

Effect of Hydroxycitrate (HCA) on Urine Chemistry in Calcium Kidney Stone Formers

Effect of Hydroxycitrate (HCA) on Urine Chemistry in Calcium Kidney Stone Formers

Body Mass Index (BMI) and Kidney Stone Risk in Calcium Kidney Stone Formers

Body Mass Index (BMI) and Kidney Stone Risk in Calcium Kidney Stone Formers