Calcium Oxalate Supersaturation Research Articles

Comparison of metabolic parameters between pure-uric acid and mixed-uric acid kidney stone formers.

We seek to compare clinical and 24-h urine parameters between pure-uric acid (UA) and UA-CaOx stone formers in our practice and explore how any differences in metabolic profiles could suggest different prevention strategies between the two groups. We retrospectively reviewed patients with either pure- or mixed-UA nephrolithiasis from 2020 to 2023 at a tertiary care center. We included patients with a 24-h urine collection and a stone analysis detecting any amount of UA. Patients were organized into two cohorts: (1) those with 100% UA stones and (2) < 100% UA stones. Differences in demographic characteristics were compared between pure-UA and UA-CaOx stone formers. Twenty-four hour urine metabolic parameters as well as metabolic abnormalities were compared between the pure-uric acid and mixed-uric acid groups. We identified 33 pure-UA patients and 33 mixed-UA patients. Patient demographics were similar between the groups (Table1). Pure- and mixed-UA patients had a similar incidence of metabolic syndrome, diabetes, history of stones, and stone burden. Table1 Demographic and baseline characteristics among pure- and mixed-uric acid stone formers Pure-uric acid stones (n = 33) Mixed-uric acid stones (n = 33) p-value Median age [IQR] 63.00 [58.00-72.50] 63.00 [53.50-68.00] 0.339 Median BMI [IQR] 28.79 [25.81-33.07] 27.96 [25.81-29.55] 0.534 Gender, n (%) 1.000 Male 21 (63.6) 21 (63.6) Female 12 (36.4) 12 (36.4) Metabolic syndrome, n (%) 17 (51.5) 16 (48.5) 0.806 Diabetes, n (%) 13 (39.4) 12 (36.4) 0.800 History of stones, n (%) 23 (69.7) 22 (66.7) 0.792 Median total stone burden, mm [IQR] 12.00 [6.00-26.50] 13.00 [7.05-20.00] 0.995 Median serum uric acid, mg/dL [IQR] 6.20 [4.80-7.15] 5.90 [4.98-6.89] 0.582 IQR Interquartile range BMI Body Mass Index n number We found the pure-UA cohort to have 24-h lower urine volume (1.53 vs. 1.96 L/day, p = 0.045) and citrate levels (286 vs. 457mg/day, p = 0.036). UA-CaOx stone formers had higher urinary calcium levels (144 vs. 68mg/day, p = 0.003), higher urinary oxalate levels (38 vs. 30mg/day, p = 0.017), and higher median urinary calcium oxalate super-saturation (3.97 vs. 3.06, p = 0.047). Pure-UA kidney stone formers have different urinary metabolic parameters when compared with UA-CaOx stone formers, thus requiring different and tailored medical management.

Urolitiáza u pacientů s idiopatickými střevními záněty – možnosti prevence a metabolického ovlivnění

Inflammatory bowel diseases (IBD) are typically accompanied by diarrhoea and frequently by malabsorption, both of which are predisposing factors for the formation of renal calculi. In patients who have not undergone bowel surgery the prevalence of urolithiasis has ranged from 1.5 to 5%, but after surgery, stone prevalence can increase to up to 16%. Enteric hyperoxaluria is a frequent complication of inflammatory bowel diseases after ileal-coecal resection, ileostomy, colostomy resection and bariatric surgery. The excess of oxalate is primarily excreted by the kidneys. Increased urinary excretion of oxalate results in urinary calcium oxalate supersaturation, leading to crystal aggregation, urolithiasis, and/or nephrocalcinosis. Prevention of oxalate lithiasis includes high fluid intake, nutritionally balanced low-oxalate, low-fat, low-salt diet, prescription of oral citrate and magnesium, calcium supplement, and also biological manipulation of intestinal flora (microbiota). In IBD patients, urolithiasis can be associated with serious urinary tract infection – in some cases asymptomatic – which can lead to chronic renal insufficiency and failure. New therapeutic approaches to patients with inflammatory bowel diseases have completely changed the natural history of these diseases with reduced number of bowel surgery. Whether this has changed the prevalence and risk factors for urinary calculi in patients with inflammatory bowel diseases is still unknown.

Risk Profile of Patients with Brushite Stone Disease and the Impact of Diet.

This study examined the profile of patients and the impact of diet on the risk of brushite stone formation under controlled, standardized conditions. Sixty-five patients with brushite nephrolithiasis were enrolled in the study. Metabolic, dietary, and 24 h urinary parameters were collected under the habitual, self-selected diet of the patients and the balanced mixed, standardized diet. The [13C2]oxalate absorption, ammonium chloride, and calcium loading tests were conducted. All patients had at least one abnormality on the usual diet, with hypercalciuria (84.6%), increased urine pH (61.5%), and hyperphosphaturia (43.1%) being the most common. Absorptive hypercalciuria was present in 32.1% and hyperabsorption of oxalate in 41.2%, while distal renal tubular acidosis (dRTA) was noted in 50% of brushite stone formers. The relative supersaturation of brushite did not differ between patients with and without dRTA. Among all recent brushite-containing calculi, 61.5% were mixed with calcium oxalate and/or carbonate apatite. The relative supersaturation of brushite, apatite, and calcium oxalate decreased significantly under the balanced diet, mainly due to the significant decline in urinary calcium, phosphate, and oxalate excretion. Dietary intervention was shown to be effective and should be an integral part of the treatment of brushite stone disease. Further research on the role of dRTA in brushite stone formation is needed.

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.

End Point Considerations for Clinical Trials in Enteric Hyperoxaluria.

Enteric hyperoxaluria is a medical condition characterized by elevated urinary oxalate excretion due to increased gastrointestinal oxalate absorption. Causative features include fat malabsorption and/or increased intestinal permeability to oxalate. Enteric hyperoxaluria has long been known to cause nephrolithiasis and nephrocalcinosis, and, more recently, an association with CKD and kidney failure has been shown. Currently, there are no US Food and Drug Administration-approved therapies for enteric hyperoxaluria, and it is unclear what end points should be used to evaluate the efficacy of new drugs and biologics for this condition. This study represents work of a multidisciplinary group convened by the Kidney Health Initiative to review the evidence supporting potential end points for clinical trials in enteric hyperoxaluria. A potential clinical outcome is symptomatic kidney stone events. Potential surrogate end points include ( 1 ) an irreversible loss of kidney function as a surrogate for progression to kidney failure, ( 2 ) asymptomatic kidney stone growth/new stone formation observed on imaging as a surrogate for symptomatic kidney stone events, ( 3 ) urinary oxalate and urinary calcium oxalate supersaturation as surrogates for the development of symptomatic kidney stone events, and ( 4) plasma oxalate as a surrogate for the development of the clinical manifestations of systemic oxalosis. Unfortunately, because of gaps in the data, this Kidney Health Initiative workgroup was unable to provide definitive recommendations. Work is underway to obtain robust information that can be used to inform trial design and medical product development in this space.

Atypical clinical presentation and management of urinary stone disease in non-verbal non-ambulatory children

Management of kidney stones primarily depends on various factors such as the presence of urinary tract obstruction, pain, stone size, location, impact on renal function, and the existence of infection. Renal colic is the classic presentation of an obstructive kidney stone. However, in this study, we present a cohort of non-verbal non-ambulatory (NVNA) patients who exhibit a distinct and uncommon presentation of kidney stones due to their medical conditions. Information about kidney stone disease in this gropup of complex pediatric patients is, scarce and their associated risk factors are not well understood. Therefore, we aim to summarize the clinical presentation, and management challenges in this unique group of NVNA patients to identify potential variables for prospective studies. A retrospective chart review was completed for all NVNA patients seen at the pediatric multidisciplinary kidney stone clinic between July 2020 to August 2022. Demographic variables, clinical presentation data, metabolic evaluation, radiological imaging, and surgical management was included for analysis. A total of 224 pediatric patients were referred to the multidisciplinary stone clinic. Of those, 27 were identified to be NVNA. The most common primary diagnosis was Cerebral Palsy followed by Lennox-Gastaut syndrome. Average age at first kidney stone presentation was 11.5 years±5.7 years. An obstructing stone was diagnosed in 18 (66%) patients, 4 (22.2%) of these presented with sepsis. Average stone burden was 9.2mm (±5.8mm). Of the obstructing stones, 13 (72%) were in the kidney. All patients with an obstructing stone underwent surgical management with retrograde endoscopic approach. Metabolic 24-h-urine analysis was completed in 24 (89%) patients. 17 (62%) had an elevated urine density, 15 (55%) demonstrated calcium oxalate supersaturation, 12 (44%) met criteria for acidosis, and 7 (26%) had significant hypocitraturia. NVNA patients represent a unique cohort whose clinical presentation is atypical. Limited ability to express symptoms makes early detection difficult to recognize. Twenty two percent of patients present with sepsis as their first manifestation of an acutely obstructing kidney stone. Pain is subjectively interpreted by caregivers and is an uncommon symptom. Our cohort demonstrates common risk factors for stones including propensity for chronic dehydration, slow urinary tract transit, ineffective bladder emptying, G-tube feeding, and lithogenic medications. NVNA pediatric patients have atypical kidney stone clinical presentation. Awareness of this unique group of patients should support future collaborative studies to focus on understanding these atypical presentations and reflect on improving management.

Effect of preoperative metabolic profiling to reduce the risk of kidneystones after bariatric surgery in patients with a historyofstoneformation.

Roux-en-Y gastric bypass (RYGB) is associated with an increased risk of kidney stone formation. This is not observed after sleeve gastrectomy (SG). Aim of this study was to assess whether preoperative metabolic profiling is helpful in selecting the most optimal bariatric procedure for patients with a kidney stone history. General hospital, the Netherlands. Patients with a kidney stone history and in the run up to bariatric surgery were screened with non-contrast abdominal computed tomography (CT), serum profiling, and 24-hour urine analysis. Those with stones on radiologic imaging and/or high preoperative urinary oxalate were advised to undergo SG instead of RYGB. Pre- and postoperative urine and serum profile differences between both groups were evaluated retrospectively. Postoperatively, RYGB (N = 28, M:F = 8:20) was associated with a 23.5% reduction in urinary volume, a 85% increase in urinary oxalate excretion with a 230% increase in calcium oxalate (CaOx) supersaturation and a 62% decrease in urinary citrate. Although SG (N = 30, M:F = 12:18) was also associated with a reduction in urinary volume, it had no adverse effects on urinary oxalate and citrate excretion, nor on calcium oxalate supersaturation (CaOx-SS). Both RYGB and SG showed favorable effects on postoperative sodium, calcium, uric acid, and phosphate excretion. This study indicates that preoperative metabolic profiling is important to select the optimal bariatric procedure in patients with an a priori increased risk of kidney stone development. These patients should be strongly encouraged to undergo SG instead of RYGB to prevent progressive or recurrent kidney stone disease.

Associations between Net Gastrointestinal Alkali Absorption, 24-Hour Urine Lithogenic Factors, and Kidney Stones.

It is not clear whether kidney stone formers have an abnormal handling of alkali and acid precursors in the gut, which might affect urine composition and ultimately stone formation. In this study, we aimed to investigate the determinants of net gastrointestinal alkali absorption and its associations with key urinary parameters in a large group of stone formers and non-stone formers. Data were collected from three independent cohorts with at least one 24-hour urine collection. We explored potential determinants of net gastrointestinal alkali absorption and the association between net gastrointestinal alkali absorption, urinary parameters, and stone former status. Finally, we estimated the proportion of the association between urine parameters and stone former status explained by differences in net gastrointestinal alkali absorption. The analysis included 6067 participants (1102 men and 4965 women; 698 and 1804 of whom were stone formers, respectively). Average net gastrointestinal alkali absorption values were consistently lower in stone formers across the three cohorts (from -15.0 to -4.9 mEq/d). Age was directly associated with net gastrointestinal alkali absorption, whereas body mass index and net endogenous acid production were inversely associated. Net gastrointestinal alkali absorption was inversely associated with supersaturation for calcium oxalate, uric acid, and renal net acid excretion and directly associated with supersaturation for calcium phosphate, urine pH, and citrate. The odds of being a stone former was 15% (13%-17%) lower per 10 mEq/24 hours higher net gastrointestinal alkali absorption. Differences in net gastrointestinal alkali absorption explained a modest amount of the differences between stone formers and non-stone formers for supersaturation for calcium oxalate (6.3%) and a sizable amount for supersaturation for uric acid (15.2%), urine pH (38.3%), citrate (26.2%), and renal net acid excretion (63.4%). Kidney stone formers have lower net gastrointestinal alkali absorption, and this explains differences in urine composition and the likelihood of stone formation.

MP10-02 DIETARY INTERVENTION IN ENTERIC HYPEROXALURIA

You have accessJournal of UrologyCME1 Apr 2023MP10-02 DIETARY INTERVENTION IN ENTERIC HYPEROXALURIA William DeFoor, Joonsue Lee, Nehus Edward, Marion Schulte, Sydney Huesman, Ashleigh Libs, and Prasad Devarajan William DeFoorWilliam DeFoor More articles by this author , Joonsue LeeJoonsue Lee More articles by this author , Nehus EdwardNehus Edward More articles by this author , Marion SchulteMarion Schulte More articles by this author , Sydney HuesmanSydney Huesman More articles by this author , Ashleigh LibsAshleigh Libs More articles by this author , and Prasad DevarajanPrasad Devarajan More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003225.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Medically complex, gastrostomy-fed children are particularly vulnerable to forming kidney stones. We have previously shown that there are elevated urinary oxalate levels in patients using enteral feeding formulas primarily based on soy protein, a known high oxalate food. Enteric hyperoxaluria may predispose patients to calcium oxalate stones. The objective of this study is assess if targeted dietary intervention decreases urinary oxalate excretion. METHODS: A retrospective cohort study was performed on medically complex children with cerebral palsy and severe developmental delay presenting to a high-volume Pediatric Stone Center with nephrolithiasis from 2015 to 2020. Inclusion criteria included those who underwent a dietary and urinary metabolic evaluation before and after the index visit. Diets were analyzed by a registered dietitian. Urinary metabolites including calcium, oxalate, and citrate as well as the supersaturations of calcium oxalate and calcium phosphate were analyzed via two 24-hour urine collections. Dietary oxalate load was determined by evaluating individual recipes for known high oxalate ingredients or soy-based formulas. Patients were stratified into those on a low versus high oxalate diet. Statistical analysis was performed using paired t-tests. RESULTS: A total of 13 medically complex stone-forming children met inclusion criteria. All patients were non-ambulatory. 11 of 13 (85%) were primarily fed via gastrostomy. Of the 13 patients, 4 were on a low oxalate diet and 9 were found to have a diet of high oxalate foods. The baseline urinary oxalate excretion (26 vs. 71 mg/m2/day, P = 0.001) and supersaturation of calcium oxalate (6.1 vs. 14.3, P=0.01) were lower in those with a low oxalate diet. Four patients on high oxalate diets were targeted for lowering the enteral oxalate load. A follow-up urinary metabolic evaluation was performed a mean of 6.5 months after the dietary intervention. The urinary oxalate level decreased from 71 to 33 mg/m2/day (P=0.049). Urinary excretion of calcium and citrate as well as the supersaturation of calcium phosphate were similar following dietary modifications. CONCLUSIONS: Urinary oxalate excretion and supersaturation of calcium oxalate were elevated in medically complex stone-forming children with high dietary oxalate content. Targeted dietary intervention to reduce the oxalate load in enteral formulas can lead to a substantial decrease in urinary oxalate excretion. Further investigation is required to determine if this leads to lower stone recurrence, hospitalizations, and the need for surgical interventions. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e114 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information William DeFoor More articles by this author Joonsue Lee More articles by this author Nehus Edward More articles by this author Marion Schulte More articles by this author Sydney Huesman More articles by this author Ashleigh Libs More articles by this author Prasad Devarajan More articles by this author Expand All Advertisement PDF downloadLoading ...

MP16-09 VITAMIN C THERAPY IN CANCER PATIENTS: IDENTIFYING PREDICTORS OF STONE FORMATION

You have accessJournal of UrologyCME1 Apr 2023MP16-09 VITAMIN C THERAPY IN CANCER PATIENTS: IDENTIFYING PREDICTORS OF STONE FORMATION Reza Roshandel, Christine W. Liaw, Mira T. Keddis, John C. Lieskec, Kevin Koo, and Aaron M. Potretzke Reza RoshandelReza Roshandel More articles by this author , Christine W. LiawChristine W. Liaw More articles by this author , Mira T. KeddisMira T. Keddis More articles by this author , John C. LieskecJohn C. Lieskec More articles by this author , Kevin KooKevin Koo More articles by this author , and Aaron M. PotretzkeAaron M. Potretzke More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003236.09AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Vitamin C has been proposed as a complementary therapy in cancer patients to improve survival and quality of life. However, vitamin C is a known metabolic precursor of oxalate, potentially increasing the risk of kidney stone disease. We aimed to investigate potential associations between vitamin C parameters and stone formation in malignancies. METHODS: Patients with cancer who were taking vitamin C ≥200 mg for ≥3 months were retrospectively identified from using ICD-10 and CPT codes. Those with recurrent urolithiasis (≥2 stone events) or a history of stone >3 mm within the year prior to vitamin C initiation were excluded from the study. New kidney stone formation were characterized based on imaging studies before and after initiation of vitamin C. Descriptive statistics and logistic regression were used to analyze stone formation risk and investigate potential predictors. RESULTS: A total of 81 patients were included. Patient demographics and vitamin C therapy details are summarized in Table 1. Median age for total cohort was 64 years. 42 patients had solid cancers (urologic and non-urologic) and 29 had hematologic malignancies. Median dose and duration of supplementation were 500 mg and 6 years, respectively, with a mean cumulative dose of 1.4 kilograms. Duration and cumulative dose of vitamin C were associated with new stone development (Figure 1). Moreover, a significant association was found between calcium oxalate supersaturation and the risk of subsequent stone formation regardless of dose differences. (RR=2.54, p=0.01). CONCLUSIONS: Our findings suggest that vitamin C supplementation confer lithogenic risk in cancer patients that may happen at doses lower than previously suggested. Furthermore, the duration of supplementation may affect cumulative risk of new stone disease as an independent risk factor. Our results also reinforce the importance of supersaturation urinary testing in this cohort of patients. Source of Funding: N/A © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e205 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Reza Roshandel More articles by this author Christine W. Liaw More articles by this author Mira T. Keddis More articles by this author John C. Lieskec More articles by this author Kevin Koo More articles by this author Aaron M. Potretzke More articles by this author Expand All Advertisement PDF downloadLoading ...

MP16-10 EFFECTS OF 24-HOUR URINARY CALCIUM OXALATE SUPERSATURATION LEVELS ON STONE GROWTH AND NEW STONE FORMATION: WHEN TO WORRY, WHEN TO NOT?

You have accessJournal of UrologyCME1 Apr 2023MP16-10 EFFECTS OF 24-HOUR URINARY CALCIUM OXALATE SUPERSATURATION LEVELS ON STONE GROWTH AND NEW STONE FORMATION: WHEN TO WORRY, WHEN TO NOT? Antonio R. H. Gorgen, Kalon L. Morgan, Andrei D. Cumpanas, Minh-Chau Vu, Jenny Liu, Seyed Amiryaghoub M. Lavasani, Kelvin Vo, Allen Rojhani, Zachary E. Tano, Sohrab N. Ali, Pengbo Jiang, Roshan M. Patel, Jaime Landman, and Ralph V. Clayman Antonio R. H. GorgenAntonio R. H. Gorgen More articles by this author , Kalon L. MorganKalon L. Morgan More articles by this author , Andrei D. CumpanasAndrei D. Cumpanas More articles by this author , Minh-Chau VuMinh-Chau Vu More articles by this author , Jenny LiuJenny Liu More articles by this author , Seyed Amiryaghoub M. LavasaniSeyed Amiryaghoub M. Lavasani More articles by this author , Kelvin VoKelvin Vo More articles by this author , Allen RojhaniAllen Rojhani More articles by this author , Zachary E. TanoZachary E. Tano More articles by this author , Sohrab N. AliSohrab N. Ali More articles by this author , Pengbo JiangPengbo Jiang More articles by this author , Roshan M. PatelRoshan M. Patel More articles by this author , Jaime LandmanJaime Landman More articles by this author , and Ralph V. ClaymanRalph V. Clayman More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003236.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Medical management for calcium oxalate (CaOx) urolithiasis commonly focuses on reducing CaOx supersaturation (SS). Using sequential computed tomography (CT) calculated 3D stone volume in conjunction with 24-hour CaOx SS levels, we sought to define CaOx SS thresholds for stable vs. increasing stone volume. METHODS: Thirty-four patients with a stone composition ≥50% CaOx and without interval stone passage or treatment, underwent 3D segmentation renal stone volume determinations based on two sequential CT scans a median of 406 days apart (range 98 to 2563 days) with at least 2 corresponding 24-hour urine analyses (i.e., Litholink™), obtained within 4 months of each CT scan. Increased stone volume was defined as ≥15% increase from baseline. T test and logistic regression were performed to evaluate CaOx SS levels among patients with and without a change in stone volume. RESULTS: An increase in stone volume occurred in 26 patients (76.5%); these individuals had a CaOx SS that was significantly higher for mean of baseline (SS 6.96 vs. 4.45), average (SS 6.79 vs. 4.12) and maximum (SS 9.20 vs. 5.45) (Figure 1); overall, there was a positive relationship between increase in CaOx SS and increased stone volume (p=0.043, p=0.014, p=0.024, respectively). The best predictor of an increase in stone volume was average CaOx SS (OR: 1.57, 95% CI 1.08 to 2.44). CONCLUSIONS: Among patients with CaOx kidney stones, 24-hour urine CaOx SS was positively associated with an increase in stone volume. CaOx SS below 3 appears favorable, whereas levels over 5 are concerning. Each additional point rise in average CaOx SS was associated with a three-fold higher risk of increased stone volume. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e206 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Antonio R. H. Gorgen More articles by this author Kalon L. Morgan More articles by this author Andrei D. Cumpanas More articles by this author Minh-Chau Vu More articles by this author Jenny Liu More articles by this author Seyed Amiryaghoub M. Lavasani More articles by this author Kelvin Vo More articles by this author Allen Rojhani More articles by this author Zachary E. Tano More articles by this author Sohrab N. Ali More articles by this author Pengbo Jiang More articles by this author Roshan M. Patel More articles by this author Jaime Landman More articles by this author Ralph V. Clayman More articles by this author Expand All Advertisement PDF downloadLoading ...

Characterization of Stone Events in Patients With Type 3 Primary Hyperoxaluria.

Hallmarks of primary hyperoxaluria type 3 are nephrolithiasis and hyperoxaluria. However, little is known about factors influencing stone formation in this disease. We characterized stone events and examined associations with urine parameters and kidney function in a primary hyperoxaluria type 3 population. We retrospectively analyzed clinical, and laboratory data of 70 primary hyperoxaluria type 3 patients enrolled in the Rare Kidney Stone Consortium Primary Hyperoxaluria Registry. Kidney stones occurred in 65/70 primary hyperoxaluria type 3 patients (93%). Among the 49 patients with imaging available, the median (IQR) number of stones was 4 (2, 5), with largest stone 7 mm (4, 10) at first imaging. Clinical stone events occurred in 62/70 (89%) with median number of events per patient 3 (2, 6; range 1-49). Age at first stone event was 3 years (0.99, 8.7). Lifetime stone event rate was 0.19 events/year (0.12, 0.38) during follow-up of 10.7 (4.2, 26.3) years. Among 326 total clinical stone events, 139 (42.6%) required surgical intervention. High stone event rates persisted for most patients through the sixth decade of life. Analysis was available for 55 stones: pure calcium oxalate accounted for 69%, with mixed calcium oxalate and phosphate in 22%. Higher calcium oxalate supersaturation was associated with increased lifetime stone event rate after adjusting for age at first event (IRR [95%CI] 1.23 [1.16, 1.32]; P < .001). By the fourth decade, estimated glomerular filtration rate was lower in primary hyperoxaluria type 3 patients than the general population. Stones impose a lifelong burden on primary hyperoxaluria type 3 patients. Reducing urinary calcium oxalate supersaturation may reduce event frequency and surgical intervention.

Urinary Risk Profile, Impact of Diet, and Risk of Calcium Oxalate Urolithiasis in Idiopathic Uric Acid Stone Disease.

The role of diet in the pathogenesis of uric acid (UA) nephrolithiasis is incompletely understood. This study investigated the effect of dietary intervention on the risk of UA stone formation under standardized conditions. Twenty patients with idiopathic UA stone disease were included in the study. Dietary intake and 24 h urinary parameters were collected on the usual diet of the patients and a standardized balanced mixed diet. Although urinary UA excretion did not change, the relative supersaturation of UA decreased significantly by 47% under the balanced diet primarily due to the significant increase in urine volume and pH. Urinary pH was below 5.8 in 85% of patients under the usual diet, and in 60% of patients under the balanced diet. The supersaturation of calcium oxalate declined significantly under the balanced diet due to the significant decrease in urinary calcium and oxalate excretion and the increase in urine volume. Dietary intervention is a key component in the management of UA nephrolithiasis. Urinary calcium and oxalate excretion should also be monitored in patients with pure UA calculi to reduce the risk of mixed stone formation with calcium oxalate. Lower urinary pH in UA stone patients can only be partially explained by diet.

Dietary weight loss strategies for kidney stone patients

PurposeOverweight has been associated with an increased risk of incident and recurrent kidney stone disease. Weight reduction is the therapeutic consequence to decrease the risk of stone formation. This review examines the effectiveness of different weight loss strategies on weight reduction and cardiometabolic risk profile, with a particular focus on risk factors for urolithiasis.MethodsA selective literature search was performed using PubMed and Cochrane library.ResultsClinical evidence for the potential benefits of dietary weight loss strategies for kidney stone disease is limited. A conventional, energy-restricted diet may significantly induce weight loss and reduce urinary supersaturation of calcium oxalate in overweight individuals with or without a history of stone formation. The current data indicate that an energy-restricted diet with partial meal replacement may additionally decrease the relative supersaturation of uric acid and further improve the cardiometabolic risk profile, and, thus, may be a favourable option for overweight kidney stone patients. Studies on the Mediterranean and DASH diets on the association between weight loss and the risk of urinary stone formation are lacking.ConclusionAn energy-restricted diet with or without meal replacement could be a promising weight loss strategy for overweight kidney stone patients. Further studies are needed to evaluate the impact of different weight loss strategies on urinary risk factors and cardiometabolic risk profile in urolithiasis.

Effect of Two Different Dietary Weight Loss Strategies on Risk Factors for Urinary Stone Formation and Cardiometabolic Risk Profile in Overweight Women

Overweight has been suggested to increase the risk of kidney stone formation. Although weight reduction might affect risk factors for urolithiasis, findings on the impact of different dietary weight loss strategies are limited. This randomized, controlled study evaluated the effect of a conventional energy-restricted modified diet with (MR group) or without meal replacement (C group) on risk factors for stone formation in overweight women without a history of urolithiasis. Of 105 participants, 78 were included into the per-protocol analysis. Anthropometric, clinical, biochemical, and 24 h urinary parameters were collected at baseline and after 12 weeks. Although both dietary interventions resulted in a significant weight reduction, relative weight loss and rate of responders were higher in the MR group. Weight loss improved cardiometabolic risk profile in both groups. Unfortunately, the benefit of decreased GPT activity in the C group was offset by a significant increase in homocysteine and a decline in GFR. While the relative supersaturation of calcium oxalate decreased significantly in both groups, a significant decline in serum uric acid concentration and relative supersaturation of uric acid was observed only in the MR group. Finally, the energy-restricted modified diet with meal replacement showed significant advantages over the energy-restricted modified diet alone.

Clinical Effectiveness of Calcium Oxalate Stone Treatments

Introduction: Lowering kidney stone risk and urine calcium oxalate supersaturation is a primary clinical focus for kidney stone prevention and can be achieved with multiple strategies. Common strategies include advice to increase fluid intake, restrict dietary sodium, or prescribing a thiazide-type diuretic. We investigated how physicians make these decisions in real-world practice and evaluate their efficacy based on 24-h urine collections. Methods: We reviewed medical charts for 203 kidney stone formers with idiopathic calcium stones from University of Chicago Kidney Stone Clinic between 2005 and 2020. Patients had three 24-h urines before an initial pre-treatment clinic visit and one follow-up 24-h urine. We analyzed changes in urine composition based on treatment advice using t tests and ANOVA. Results: Patients who received advice to increase fluid intake had lower urine volume at baseline (1.5 vs. 2.5 L/day, p < 0.001) and larger increase in urine volume at follow-up (0.6 vs. 0.1 L/day, p < 0.001) compared to those who did not receive the advice. Patients who were advised to restrict dietary sodium had a higher urine sodium at baseline (208 vs. 139 mEq/day, p < 0.001), a larger reduction in urine sodium (−28 vs. 13 mEq/day, p = 0.002), and larger reduction in urine calcium (−74 vs. −28 mg/day, p = 0.005) compared with those not advised to restrict dietary sodium. Patients started on a thiazide had a higher baseline urine calcium (281 vs. 213 mg/day) and larger reduction in urine calcium (−83 vs. −9 mg/day, p < 0.001) compared with patients not started on a thiazide. In combination, thiazide prescriptions with dietary sodium restriction reduced urine calcium by 99 mg/day and reduced calcium oxalate supersaturation from 8.0 to 5.5 and calcium phosphate supersaturation from 1.4 to 1.0. Conclusion: Providers use 24-h urine data to guide treatment strategy decisions. These strategies achieved the intended effects on urine composition and lowered kidney stone risk.

What treatments reduce kidney stone risk in patients with bowel disease?

We examined how physicians made therapeutic choices to decrease stone risk in patients with bowel disease without colon resection, many of whom have enteric hyperoxaluria (EH), at a single clinic. We analyzed clinic records and 24-h urine collections before and after the first clinic visit, among 100 stone formers with bowel disease. We used multivariate linear regression and t tests to compare effects of fluid intake, alkali supplementation, and oxalate-focused interventions on urine characteristics. Patients advised to increase fluid intake had lower initial urine volumes (L/day; 1.3 ± 0.5 vs. 1.7 ± 0.7) and increased volume more than those not so advised (0.7 ± 0.6 vs. 0.3 ± 0.6 p = 0.03; intervention vs. non-intervention). Calcium oxalate supersaturation (CaOx SS) fell (95% CI -4.3 to -0.8). Alkali supplementation increased urine pH (0.34 ± 0.53 vs. 0.22 ± 0.55, p = 0.26) and urine citrate (mg/d; 83 ± 256 vs. 98 ± 166, p = 0.74). Patients advised to reduce oxalate (mg/day) absorption had higher urine oxalate at baseline (88 ± 44 vs. 50 ± 26) which was unchanged on follow-up (88 (baseline) vs. 91 (follow-up), p = 0.90). Neither alkali (95% CI -1.4 to 2.1) nor oxalate-focused advice (95% CI -1.2 to 2.3) lowered CaOx SS. Physicians chose treatments based on baseline urine characteristics. Advice to increase fluid intake increased urine volume and decreased CaOx SS. Alkali and oxalate interventions were ineffective.

Beneficial effects of a prescription home-prepared diet and of zucchini on urine calcium oxalate supersaturation and urinary parameters in adult cats.

From the authors' experience, the consumption of a balanced prescription home-prepared diet that includes zucchini (courgette) benefits cats with recurrent urolithiasis, but there is no published evidence to support this. The aim was to study the effects on urinary parameters of (1) a balanced prescription home-prepared diet containing zucchini, and (2) the addition of zucchini to a dry food, compared with two commercial therapeutic diets. Eight healthy cats were included in a Latin-square designed protocol. Five diets were evaluated: two commercial diets, designed for cats with urinary disorders, one high-moisture (U-WET) and one high-sodium dry (U-DRY); one home-prepared diet (HOME); one commercial dry food for adult maintenance (DRY); and DRY given together with 10 g of zucchini per kg body weight (DRY-Zuc). After a 7-day adaptation period, urine was collected and daily food and water intakes were assessed for 12 days. Urinary parameters, and relative supersaturation (RSS) for calcium oxalate (CaOx) and struvite, were determined. Data underwent repeated measures ANOVA analysis. The digestibility of energy, dry matter, protein and fat was highest with the HOME diet. CaOx RSS was lowest in cats eating the HOME diet, but not significantly different from the U-WET or U-DRY diets. CaOx RSS was lower in cats eating the DRY-Zuc diet than in cats eating the DRY diet. Struvite RSS did not differ significantly among groups. This study shows that a balanced prescription home-prepared diet was safe and allowed a very low urinary CaOx RSS. It also showed that adding zucchini to dry food lowered the urine CaOx RSS.

Defining 24-hour urine parameters and kidney stone risk of student athletes.

Dehydration is a risk factor for kidney stone formation. Studying populations that may experience dehydration without a known increased incidence of stone formation may help understand stone formation and prevention. High-caliber athletes represent such a population. We characterized the urinary environment of high-caliber athletes utilizing 24-hour urine collections with comparison to non-athlete controls. After Institutional Review Board (IRB) and National Collegiate Athletic Association (NCAA) compliance officer approval, 74 college-student athletes and 20 non-athletes were enrolled. Demographics, medical history, and sport of participation were recorded. Participants were asked to provide 24-hour urine collections as well as diet and activity logs at the time of urine collection. Standard stone risk parameters were assessed and compared to litholink reference standards. 34 athletes and 10 non-athletes provided at least one 24-hour urine specimen for evaluation. Athletes had a high prevalence of urinary risks for stone formation including low volume (median 1.46L), low citrate, high sodium, high calcium (females), and high uric acid (males). However, athletes also had a high prevalence of known stone-protective factors such as high urine magnesium. Athletes had a lower urine pH but high supersaturation of uric acid and calcium oxalate compared to non-athletes. Student athletes appear to have a high prevalence of urinary risk factors for stone formation such as dehydration, high calcium, high uric acid, high sodium, and low citrate. Overall stone risk in this population may be offset by increased levels of stone-protective factors such as magnesium. Further study of this population may help generate hypotheses for effective stone prevention strategies in the general population.

Effect of Black Tea Consumption on Urinary Risk Factors for Kidney Stone Formation.

Copious fluid intake is the most essential nutritional measure in the treatment of urolithiasis, and is suggested to be a protective factor in the primary prevention of urinary stone formation. Although the intake of black tea contributes to daily fluid intake, the high oxalate content could outweigh the beneficial effect of urine dilution. The present study investigated the effect of black tea consumption on urinary risk factors for kidney stone formation. Ten healthy men received a standardized diet for a period of ten days. Subjects consumed 1.5 L/day of fruit tea (0 mg/day oxalate) during the 5-day control phase, which was replaced by 1.5 L/day of black tea (86 mg/day oxalate) during the 5-day test phase. Fractional and 24-h urines were obtained. The intake of black tea did not significantly alter 24-h urinary oxalate excretion. Urinary citrate, an important inhibitor of calcium stone formation, increased significantly, while the relative supersaturation of calcium oxalate, uric acid, and struvite remained unchanged. No significantly increased risk for kidney stone formation could be derived from the ingestion of black tea in normal subjects. Further research is needed to evaluate the impact of black tea consumption in kidney stone patients with intestinal hyperabsorption of oxalate.