Predictor for uric acid stones: Mean stone density, stone heterogeneity index, and variation coefficient of stone density on single-energy NCCT, and urine pH

We analyzed the capacities of pertinent parameters (determined by single-energy non-contrast computed tomography [NCCT]) and urinary pH to predict uric acid stones. We reviewed the medical records of 501 patients whose stones were removed surgically or passed spontaneously between December 2014 and April 2016. Qualifying participants (n = 420) were stratified by the nature of the stone (calcium oxalate, uric acid, or infectious). Based on NCCT, we determined maximal stone length (MSL), mean stone density (MSD), and stone heterogeneity index (SHI) using Hounsfield units (HU) and calculated the variant coefficient of stone density (VCSD = SHI/MSD × 100). Urinary pH was also ascertained. Mean patient age was 55.55 ± 15.46 years. MSD (448.59 ± 173.21 HU), SHI (100.81 ± 77.37 HU), and VCSD (22.58 ± 10.55) proved to be significantly lower in uric acid versus other types of stones, as did urinary pH (5.33 ± 0.56; all p < 0.001). Receiver operating characteristic (ROC) curves depicting predictability of uric acid stones yielded area under ROC curve (AUC) values for MSD, SHI, VCSD, and urinary pH of 0.806 (95% CI: 0.761–0.850), 0.893 (95% CI: 0.855–0.931), 0.782 (95% CI: 0.726–0.839), and 0.797 (95% CI: 0.749–0.846), respectively, with corresponding cutpoints of 572.3 HU, 140.4 HU, 25.79, and 6.0. Among these four parameters, SHI was verifiably (DeLong’s test) the most effective predictor of uric acid stones (all p < 0.001). Compared with MSD, VCSD, and urinary pH, SHI may better predict uric acid stones, using a cutpoint of 140.4 HU.

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A comparison of the metabolic profiles of diabetic and non-diabetic uric acid stone formers

Canadian Urological Association Journal ◽

10.5489/cuaj.820 ◽

2013 ◽

Vol 7 (3-4) ◽

pp. e190-2 ◽

Cited By ~ 3

Author(s):

Alfonso Fernandez ◽

Andrew Fuller ◽

Reem Al-Bareeq ◽

Linda Nott ◽

Hassan Razvi

Keyword(s):

Uric Acid ◽

Dietary Advice ◽

Diabetic Patients ◽

Metabolic Profiles ◽

Uric Acid Stone ◽

Metabolic Evaluation ◽

Urine Ph ◽

Oxalate Excretion ◽

Stone Formers ◽

Uric Acid Stones

Introduction: The aim of this study was to compare the metabolic profiles of diabetic and non-diabetic patients with uric acid stones to understand whether preventive strategies should be tailored to reflect different causative factors.Methods: The results of the metabolic evaluation of patients with uric acid stones identified prospectively from the Metabolic Stone Clinic at St. Joseph’s Hospital, London, Canada were reviewed. Information included patients’ clinical histories, 24 hour urine collections, blood chemistry and stone analysis.Results: Complete data were obtained from 68 patients with uric acid stones. Twenty-two patients had diabetes. There were no statistically significant differences in mean age, body mass index, or history of gout. Among diabetics, pure uric acid stones were identified in 14 patients (63%) and mixed uric acid in 8 (36%). Pure uric acid stones were more common in the diabetic cohort (63% vs. 46%, p = 0.16). Urine pH, serum and urine uric acid levels and 24-hour urine volumes were similar in both groups. The diabetic group had an increased average oxalate excretion (424 μmol/d vs. 324 μmol/d, p = 0.003).Conclusion: The exact etiological basis for the higher oxalate excretion in diabetic uric acid stone formers is unclear. Whether this is a metabolic feature of diabetes, due to dietary indiscretion or the iatrogenic consequence of dietary advice requires further investigation.

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Pathophysiology and Treatment of Uric Acid Stones

10.2310/uro.11044 ◽

2018 ◽

Author(s):

Dustin Whitaker ◽

Ava Saidian ◽

Jacob Britt ◽

Carter Boyd ◽

Kyle Wood ◽

...

Keyword(s):

Diabetes Mellitus ◽

Metabolic Syndrome ◽

Uric Acid ◽

Urine Volume ◽

Potassium Citrate ◽

First Line ◽

Urine Ph ◽

Stone Composition ◽

The Metabolic Syndrome ◽

Uric Acid Stones

Uric acid is the third most common stone composition and comprises 7 to 10% of all kidney stones sent for analysis. These stones are more common with increasing age and in men. Uric acid stone disease is associated with conditions such as the metabolic syndrome and type 2 diabetes mellitus. Uric acid is produced by the enzyme, xanthine oxidase and is the final product of purine metabolism in humans. Three main factors contribute to the formation of uric acid stones: low urine pH (the most important), hyperuricosuria (rare, includes conditions such as myeloproliferative disorders and Lesch-Nyhan syndrome), and low urine volume. Uric acid stones appear radiolucent on plain radiographs and are ultimately diagnosed via stone analysis. These stones may be treated with medical expulsive therapy, dissolution therapy, or surgical intervention depending on the size, location, and clinical presentation. Urine pH manipulation therapy with potassium citrate is the first-line treatment for the prevention of uric acid stones and attempts at dissolution. Allopurinol should not be offered as the first-line therapy for uric acid stones. This review contains 3 figures, 1 table and 38 references Key Words: ammonium, diabetes mellitus, epidemiology, management, metabolic syndrome, nephrolithiasis, pathophysiology, potassium citrate, uric acid, urine pH

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Oral chemolysis is an effective, non-invasive therapy for urinary stones suspected of uric acid content

Urolithiasis ◽

10.1007/s00240-020-01204-8 ◽

2020 ◽

Vol 48 (6) ◽

pp. 501-507

Author(s):

Arman Tsaturyan ◽

Elizaveta Bokova ◽

Piet Bosshard ◽

Olivier Bonny ◽

Daniel G. Fuster ◽

...

Keyword(s):

Uric Acid ◽

Acid Content ◽

Multivariate Logistic Regression Analysis ◽

Potassium Citrate ◽

Quality Data ◽

Urinary Stones ◽

Ureteral Stones ◽

Urine Ph ◽

Stone Size ◽

Stone Density

AbstractDespite the possible benefit from avoiding stone surgery with all its possible complications, oral chemolysis is rarely performed in patients with urinary stones suspected of uric acid content. Among the reasons for its limited use is the sparse and low-quality data on its efficacy and the lack of reliable factors predicting its outcome. We thus performed a retrospective single-center cohort study of 216 patients (median patient age 63 years) with 272 renal (48%) and/or ureteral (52%) stones treated with oral chemolysis from 01/2010 to 12/2019. Patients with low urine pH (< 6), low stone density upon non-contrast enhanced computed tomography (NCCT), radiolucent urinary stones on plain radiography, and/or a history of uric acid urolithiasis were included. Potassium citrate and/or sodium/magnesium bicarbonate were used for alkalization (target urine pH 6.5–7.2). Median stone size was 9 mm, median stone density 430 Hounsfield Units. Patients with ureteral stones < 6 mm were excluded since stones this small are very likely to pass spontaneously. The stone-free status of each patient was evaluated after 3 months using NCCT. Oral chemolysis was effective with a complete and partial response rate of stones at 3 months of 61% and 14%, respectively; 25% of stones could not be dissolved. Lower stone density (OR = 0.997 [CI 0.994–0.999]; p = 0.008) and smaller stone size (OR = 0.959 [CI 0.924–0.995]; p = 0.025) significantly increased the success rate of oral chemolysis in multivariate logistic regression analysis. More precise stone diagnostics to exclude non-uric-acid stones could further improve outcome.

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Studies on the pathophysiology of the low urine pH in patients with uric acid stones

Kidney International ◽

10.1046/j.1523-1755.2002.00197.x ◽

2002 ◽

Vol 61 (3) ◽

pp. 988-994 ◽

Cited By ~ 36

Author(s):

Kamel S. Kamel ◽

Surinder Cheema-Dhadli ◽

Mitchell L. Halperin

Keyword(s):

Uric Acid ◽

Urine Ph ◽

Uric Acid Stones

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Alkalinization of the Urine and Lowering of Urine Uric Acid Content in Diabetic Patients with a Low Urine PH Results in Prevention and Dissolution of Uric Acid Stones - A Case Report and A Retrospective Outcome Study

10.47746/fmcr.2021.2501 ◽

2021 ◽

Vol 02 (05) ◽

Author(s):

David S. H. Bell ◽

Edison Goncalves

Keyword(s):

Uric Acid ◽

Case Report ◽

Acid Content ◽

Diabetic Patients ◽

Outcome Study ◽

Urine Ph ◽

Uric Acid Stones

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Prediction of Uric Acid Component in Nephrolithiasis Using Simple Clinical Information: A Machine Learning-Based model

10.21203/rs.3.rs-1012298/v1 ◽

2021 ◽

Author(s):

Hao-Wei Chen ◽

Yu-Chen Chen ◽

Jung-Ting Lee ◽

Chung-Yao Kao ◽

Yii-Her Chou ◽

...

Keyword(s):

Machine Learning ◽

Uric Acid ◽

Filtration Rate ◽

Reliable Method ◽

Estimated Glomerular Filtration Rate ◽

Clinical Information ◽

Urine Ph ◽

Uric Acid Stones ◽

Area Under Roc Curve ◽

Model Training

Abstract There is a great need for a diagnostic tool using simple clinical information collected from patients to diagnose uric acid (UA) stones in nephrolithiasis. We built a predictive model making use of machine learning (ML) methodologies entering simple parameters easily obtained at the initial clinical visit. Socio-demographic, health, and clinical data from two cohorts (A and B), both diagnosed with nephrolithiasis, one between 2012 and 2016 and the other between June and December 2020, were collected before nephrolithiasis treatment. A ML-based model for predicting UA stones in nephrolithiasis was developed using eight simple parameters - sex, age, gout, diabetes mellitus, body mass index, estimated glomerular filtration rate, bacteriuria, and urine pH. Data from Cohort A were used for model training and validation (ratio 3:2), while data from Cohort B were used only for validation. One hundred forty-six (13.3%) of 1098 patients Cohort A and three (4.23%) of 71 patients in Cohort B had pure UA stones. For Cohort A, our model achieved validation AUC (area under ROC curve) of 0.842, with 0.8475 sensitivity and 0.748 specificity. For Cohort B, our model achieved 0.936 AUC, with 1.0 sensitivity, and 0.912 specificity. This ML-based model provides a convenient and reliable method for diagnosing urolithiasis. Using only eight readily available clinical parameters, it distinguished pure uric acid stones from other stones before treatment.

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Phytotherapy and Herbal Medicines for Kidney Stones

Current Drug Targets ◽

10.2174/1389450121666200929115555 ◽

2020 ◽

Vol 22 (1) ◽

pp. 22-30

Author(s):

Esteban Emiliani ◽

Adrian Jara ◽

Andres Koey Kanashiro

Keyword(s):

Uric Acid ◽

Calcium Oxalate ◽

Kidney Stones ◽

Animal Studies ◽

Randomized Clinical Trials ◽

Herbal Medicines ◽

Phyllanthus Niruri ◽

Treatment And Prevention ◽

Number Of Patients ◽

Uric Acid Stones

Background: Kidney stones are one of the oldest known and common diseases in the urinary tract with a prevalence that varies from 1% to 20%. Many phytotherapic and herbal medicines for kidney stones have been described for their treatment and prevention. Objective: The objective of this study is to perform a comprehensive review of several phytotherapic and herbal medicines published including clinical and animal studies. Results: Phytotherapy may influence the risk of recurrence in calcium oxalate and uric acid stones. The most solid evidence suggest that Phyllanthus niruri is one of the most studied components that appear to interfere with the calcium oxalate crystallization, reduced hyperoxaluria and hiperuricosuria and increased shock wave lithotripsy efficacy due to reduced crystallization without significant adverse effects, also Theobromine have shown to reduce the crystallization of uric acid in patients and appears to be a promising supplement to treat such stones. Conclusion: Many phytoterapic and herbal agents have been studies to treat and present urolithiasis, most of them only with studies of small number of patients or in animal models. Further randomized clinical trials are needed to evaluate the effect of these agents in kidney stones.

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Incidence and Characteristics of Kidney Stones in Patients on Ketogenic Diet: A Systematic Review and Meta-Analysis

Diseases ◽

10.3390/diseases9020039 ◽

2021 ◽

Vol 9 (2) ◽

pp. 39

Author(s):

Prakrati Acharya ◽

Chirag Acharya ◽

Charat Thongprayoon ◽

Panupong Hansrivijit ◽

Swetha R. Kanduri ◽

...

Keyword(s):

Uric Acid ◽

Kidney Stones ◽

Observational Studies ◽

Meta Analysis ◽

Random Effects Model ◽

Ketogenic Diets ◽

Cochrane Database ◽

Uric Acid Stones ◽

Low Carbohydrate

Very-low-carbohydrate diets or ketogenic diets are frequently used for weight loss in adults and as a therapy for epilepsy in children. The incidence and characteristics of kidney stones in patients on ketogenic diets are not well studied. Methods: A systematic literature search was performed, using MEDLINE, EMBASE, and Cochrane Database of Systematic Reviews from the databases’ inception through April 2020. Observational studies or clinical trials that provide data on the incidence and/or types of kidney stones in patients on ketogenic diets were included. We applied a random-effects model to estimate the incidence of kidney stones. Results: A total of 36 studies with 2795 patients on ketogenic diets were enrolled. The estimated pooled incidence of kidney stones was 5.9% (95% CI, 4.6–7.6%, I2 = 47%) in patients on ketogenic diets at a mean follow-up time of 3.7 +/− 2.9 years. Subgroup analyses demonstrated the estimated pooled incidence of kidney stones of 5.8% (95% CI, 4.4–7.5%, I2 = 49%) in children and 7.9% (95% CI, 2.8–20.1%, I2 = 29%) in adults, respectively. Within reported studies, 48.7% (95% CI, 33.2–64.6%) of kidney stones were uric stones, 36.5% (95% CI, 10.6–73.6%) were calcium-based (CaOx/CaP) stones, and 27.8% (95% CI, 12.1–51.9%) were mixed uric acid and calcium-based stones, respectively. Conclusions: The estimated incidence of kidney stones in patients on ketogenic diets is 5.9%. Its incidence is approximately 5.8% in children and 7.9% in adults. Uric acid stones are the most prevalent kidney stones in patients on ketogenic diets followed by calcium-based stones. These findings may impact the prevention and clinical management of kidney stones in patients on ketogenic diets.

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