Clinical value of crystalluria and quantitative morphoconstitutional analysis of urinary calculi

Analysis of metabolic syndrome in bilateral upper urinary tract stones: A retrospective study of 3905 cases

Bilateral upper urinary tract stones are significantly related to renal function damage. However, few studies characterized the risk factors of bilateral upper urinary tract stones. We retrospectively enrolled 3905 patients with urinary tract stones from March 2019 to March 2022 at the Second Hospital of Tianjin Medical University. Patients were divided into two groups according to the location of the stones, and the related data were evaluated. In this study, 2485 unilateral and 1420 bilateral stone patients were included. Multivariate logistic regression analysis showed that BMI, gout, hyperparathyroidism, uric acid stone, urine PH, 24-h urinary calcium, blood uric acid, and metabolic syndrome (Mets) were independent risk factors for bilateral stone formation(P < 0.05). Based on these results, we construct a discrimination model. This model revealed good discrimination with an area under the receiver operating characteristic curves of 0.617, and the sensitivity and specificity were 0.592 and 0.586, respectively. Furthermore, the number of Mets components increased the risk of bilateral upper urinary tract stones. Hypertension, hyperglycemia, and low HDL level were strongly associated with bilateral upper urinary tract stones (P < 0.05). Patients with 5 components Mets had 1.89-fold higher risk of bilateral upper urinary tract stones than those with 1 component Mets (OR 3.381; 95 % CI 1.221-9.360; P = 0.013). Additionally, male patients with Mets had higher risk of bilateral upper urinary tract stones than female patients. Our analysis revealed that eight clinical factors were associated with the formation of bilateral upper urinary tract stones, namely BMI, gout, hyperparathyroidism, uric acid stone, urine PH, 24-h urinary calcium, blood uric acid, and Mets. This study could help clinicians adjust treatment strategies for high-risk patients with bilateral upper urinary tract stones.

Beneficial roles of gastrointestinal and urinary microbiomes in kidney stone prevention via their oxalate-degrading ability and beyond

Formation of calcium oxalate (CaOx) crystal, the most common composition in kidney stones, occurs following supersaturation of calcium and oxalate ions in the urine. In addition to endogenous source, another main source of calcium and oxalate ions is dietary intake. In the intestinal lumen, calcium can bind with oxalate to form precipitates to be eliminated with feces. High intake of oxalate-rich foods, inappropriate amount of daily calcium intake, defective intestinal transporters for oxalate secretion and absorption, and gastrointestinal (GI) malabsorption (i.e., from gastric bypass surgery) can enhance intestinal oxalate absorption, thereby increasing urinary oxalate level and risk of kidney stone disease (KSD). The GI microbiome rich with oxalate-degrading bacteria can reduce intestinal oxalate absorption and urinary oxalate level. In addition to the oxalate-degrading ability, the GI microbiome also affects expression of oxalate transporters and net intestinal oxalate transport, cholesterol level, and short-chain fatty acids (SCFAs) production, leading to lower KSD risk. Recent evidence also shows beneficial effects of urinary microbiome in KSD prevention. This review summarizes the current knowledge on the aforementioned aspects. Potential benefits of the GI and urinary microbiomes as probiotics for KSD prevention are emphasized. Finally, challenges and future perspectives of probiotic treatment in KSD are discussed.

Advancements in stone classification: unveiling the beauty of urolithiasis

PURPOSE

Urolithiasis has become increasingly prevalent, leading to higher disability-adjusted life years and deaths. Various stone classification systems have been developed to enhance the understanding of lithogenesis, aid urologists in treatment decisions, and predict recurrence risk. The aim of this manuscript is to provide an overview of different stone classification criteria.

METHODS

Two authors conducted a review of literature on studies relating to the classification of urolithiasis. A narrative synthesis for analysis of the studies was used.

RESULTS

Stones can be categorized based on anatomical position, size, medical imaging features, risk of recurrence, etiology, composition, and morphoconstitutional analysis. The first three mentioned offer a straightforward approach to stone classification, directly influencing treatment recommendations. With the routine use of CT imaging before treatment, precise details like anatomical location, stone dimensions, and Hounsfield Units can be easily determined, aiding treatment planning. In contrast, classifying stones based on risk of recurrence and etiology is more complex due to dependencies on multiple variables, including stone composition and morphology. A classification system based on morphoconstitutional analysis, which combines morphological stone appearance and chemical composition, has demonstrated its value. It allows for the rapid identification of crystalline phase principles, the detection of crystalline conversion processes, the determination of etiopathogenesis, the recognition of lithogenic processes, the assessment of crystal formation speed, related recurrence rates, and guidance for selecting appropriate treatment modalities.

CONCLUSIONS

Recognizing that no single classification system can comprehensively cover all aspects, the integration of all classification approaches is essential for tailoring urolithiasis patient-specific management.

Crystalluria in adolescent and adult patients with congenital heart disease

INTRODUCTION

Crystalluria is a frequent finding in normal individuals and in patients suffering from urolithiasis. As nephrolithiasis has been associated with cardiovascular risk factors and most congenital heart disease (CHD) patients reach adulthood, the objective of this study is to determine the presence of crystalluria and if it influences their cardiovascular outcome.

METHODS

Case-control and observational prospective study design of patients with CHD older than 14 years with a stable CHD verified with imaging tests and a control population.

RESULTS

214 patients with CHD [median age 21 (17-35) years and 41 (19%) males] and 345 controls were studied and followed up. None of them had symptoms of renal calculi. Nine (4%) patients with CHD and 24 (7%) patients in the control group showed crystalluria (p = 0.180), all of them composed of calcium oxalate. No significant differences were seen in age, sex, body mass index, CHD complexity, cardiovascular risk factors, NYHA functional class, cyanosis, and medical treatment between CHD patients with and without crystalluria. In relation to survival, 18 patients with CHD had a major acute cardiovascular event (MACE) (3 strokes, 2 myocardial infarction, 9 cardiovascular death and 4 non cardiovascular mortality) during the follow up time [7.3 (4.4-8.5) years] without significant differences in the Kaplan-Meier analysis (p = 0.358) between patients with and without crystalluria.

CONCLUSION

No significant differences were found between CHD and control patients in relation to crystalluria and it had no impact on the occurrence of cardiovascular events in the medium term follow up of patients with CHD.

Retrospective analysis of urinary tract stone composition in a Chinese ethnic minority colony based on Fourier transform infrared spectroscopy

To analyze the relationship between the composition of urinary stones and various influencing factors in the Enshi region. We used FT-IR to examine the composition of 1092 stone samples. Combined with the relevant clinical materials, the data were analyzed using both one-dimensional statistical methods and multivariate statistical methods. The study included 1092 stone samples, classified as follows: 457 (41.8%) with a single component, 453 (41.5%) with two components, 149 (13.6%) with three components, and 33 (3.0%) with four components. Stones were categorized into five types: Calcium Oxalate (CaOx) (76.4%), carbapatite (CaP) (9.3%), Struvite (ST) (8.3%), Uric Acid (UA) (4.9%), and Others (1.0%). Age, gender, urinary tract infection (UTI), family history of urinary stones (FH), hyperuricemia (HUA) and stone location were significantly associated with stone type. Logistic regression revealed that females and UTI were relative risk factors for predicting CaP and ST, while FH and HUA were relative risk factors for predicting UA. Our study indicates that the overall composition of urinary tract stones in the Enshi region is consistent with that of the entire China. Additionally, the predisposing factors for stone formation vary in terms of gender, age, FH, UTI, hyperuricemia HUA, and stone location.

Kidney Stone Prevention

Kidney stone disease (KSD) (alternatively nephrolithiasis or urolithiasis) is a global health care problem that affects almost people in developed and developing countries. Its prevalence has been continuously increasing with a high recurrence rate after stone removal. Although effective therapeutic modalities are available, preventive strategies for both new and recurrent stones are required to reduce physical and financial burdens of KSD. To prevent kidney stone formation, its etiology and risk factors should be first considered. Low urine output and dehydration are the common risks of all stone types, whereas hypercalciuria, hyperoxaluria, and hypocitraturia are the major risks of calcium stones. In this article, up-to-date knowledge on strategies (nutrition-based mainly) to prevent KSD is provided. Important roles of fluid intake (2.5-3.0 L/d), diuresis (>2.0-2.5 L/d), lifestyle and habit modifications (for example, maintain normal body mass index, fluid compensation for working in high-temperature environment, and avoid cigarette smoking), and dietary management [for example, sufficient calcium at 1000-1200 mg/d, limit sodium at 2 or 3-5 g/d of sodium chloride (NaCl), limit oxalate-rich foods, avoid vitamin C and vitamin D supplements, limit animal proteins to 0.8-1.0 g/kg body weight/d but increase plant proteins in patients with calcium and uric acid stone and those with hyperuricosuria, increase proportion of citrus fruits, and consider lime powder supplementation] are summarized. Moreover, uses of natural bioactive products (for example, caffeine, epigallocatechin gallate, and diosmin), medications (for example, thiazides, alkaline citrate, other alkalinizing agents, and allopurinol), bacterial eradication, and probiotics are also discussed. Adv Nutr 2023;x:xx-xx.

Quantitative analysis of calcium oxalate monohydrate and dihydrate for elucidating the formation mechanism of calcium oxalate kidney stones

We sought to identify and quantitatively analyze calcium oxalate (CaOx) kidney stones on the order of micrometers, with a focus on the quantitative identification of calcium oxalate monohydrate (COM) and dihydrate (COD). We performed Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and microfocus X-ray computed tomography measurements (microfocus X-ray CT) and compared their results. An extended analysis of the FTIR spectrum focusing on the 780 cm-1 peak made it possible to achieve a reliable analysis of the COM/COD ratio. We succeeded in the quantitative analysis of COM/COD in 50-μm2 areas by applying microscopic FTIR for thin sections of kidney stones, and by applying microfocus X-ray CT system for bulk samples. The analysis results based on the PXRD measurements with micro-sampling, the microscopic FTIR analysis of thin sections, and the microfocus X-ray CT system observation of a bulk kidney stone sample showed roughly consistent results, indicating that all three methods can be used complementarily. This quantitative analysis method evaluates the detailed CaOx composition on the preserved stone surface and provides information on the stone formation processes. This information clarifies where and which crystal phase nucleates, how the crystals grow, and how the transition from the metastable phase to the stable phase proceeds. The phase transition affects the growth rate and hardness of kidney stones and thus provides crucial clues to the kidney stone formation process.

Crystallurical profile in sheep after ammonium chloride supplementation

ABSTRACT Although urinary crystals are habitual components, urolithiasis formation is always preceded by these concretions. We aimed to identify the change in the crystalline profile in sheep supplemented with ammonium chloride. Twenty-five male sheep aged three months, feedlot and randomly distributed into three groups were used: Control Group (CG) n = 5 did not receive Ammonium Chloride; G200 Group (n=10) (200mg/kg) of Ammonium Chloride for 56 consecutive days; G500 Group (n=10) (500mg/kg) of Ammonium Chloride for 56 consecutive days, administered daily orally. Sampling times and clinical evaluation were performed at seven days, with M0 (immediately before Ammonium Chloride), M1 (seven days after) until M8, totaling 70 days of feedlot. Urine samples were performed to identify the presence, type, and quantity of crystals. There was an increase in crystalluria in all groups in relation to time due to dietary influence, mainly in the CG, which presented more crystals of amorphous calcium phosphate and calcium oxalate. In addition, the G500 Group presented a higher presence of urate/uric acid crystals after urinary acidification, which are closely related to urinary pH.

Differential identification of urine crystals with morphologic characteristics and solubility test

BACKGROUND

Urinary crystals are the most diverse forms of urine sediments. Reference images for typical urinary crystals are common, however, but images for interpreting atypical urinary crystals are very rare. The authors reviewed various forms and solubility tests of urine crystals to interpret atypical crystals found in clinical specimens.

METHODS

We reviewed textbooks on urinary crystals and articles published in PubMed. Some atypical crystals were confirmed using a solubility test.

RESULTS

The classification, shape, chemical structure, and solubility of the crystals were summarized. In the solubility test, some crystals showed different results; therefore, a new solubility test was proposed based on the literature review. We presented various types of calcium oxalates.

CONCLUSIONS

These review articles will be helpful in the examination of atypical crystals found in clinical specimens. The solubility test requires additional studies to discriminate the inconsistent results between the authors.

Thulium fiber laser's dust for stone composition analysis: Is it enough?

Introduction: We aimed to evaluate if the biochemical composition of urinary stones can be determined by analyzing the stone dust only, and whether a photo taken during the surgery could be useful for completing the morpho-constitutional analysis. Materials and methods: 20 patients went through a retrograde intrarenal surgery (RIRS) for renal stone treatment with TFL (Fiber Dust, Quanta, 2020) using 150 µm silica core laser fibers. After laser lithotripsy, residual fragments (RF) were removed with a basket (ZeroTip, Boston Scientific) and spontaneously floating stones particles were considered stone dust and were aspirated through the working channel. Pairs of RF and stone dust were labelled and sent to analysis by scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR). Photos of the stone (surface and section) were taken from videos recorded during the surgery. Results: A total of 20 patients were included in the study. Mean age was 49,8 years old with metabolic and genetic disorders. Mean stone volume was 750 mm3 for ureteral stones and 2334 mm3 for renal stones. Mean stone density was 1187 HU. Positive urine culture was found in 25% patients. In 2/20 (10%) the biochemistry differed only in the relative proportions of each constituent, whilst 5/20 (25%) only one component was missing. Laser crystalline conversion was found in 3/20 (15%). Whewellite and weddellite layers were found in photos thus adding missing information from dust stone analysis. Conclusion: Analyzing aspirated dust through the ureteroscope's working channel by physical techniques, we can understand the lithogenic process of the urinary stone, without needing to analyze the stone fragment. Morphological analysis, given by a proper stone picture, adds missing information in specific cases.

Tumor Lysis Syndrome and AKI: Beyond Crystal Mechanisms

BACKGROUND

The pathophysiology of AKI during tumor lysis syndrome (TLS) is not well understood due to the paucity of data. We aimed to decipher crystal-dependent and crystal-independent mechanisms of TLS-induced AKI.

METHODS

Crystalluria, plasma cytokine levels, and extracellular histones levels were measured in two cohorts of patients with TLS. We developed a model of TLS in syngeneic mice with acute myeloid leukemia, and analyzed ultrastructural changes in kidneys and endothelial permeability using intravital confocal microscopy. In parallel, we studied the endothelial toxicity of extracellular histones in vitro. RESULTS: The study provides the first evidence that previously described crystal-dependent mechanisms are insufficient to explain TLS-induced AKI. Extracellular histones that are released in huge amounts during TLS caused profound endothelial alterations in the mouse model. The mechanisms of histone-mediated damage implicates endothelial cell activation mediated by Toll-like receptor 4. Heparin inhibits extracellular histones and mitigates endothelial dysfunction during TLS.

CONCLUSION

This study sheds new light on the pathophysiology of TLS-induced AKI and suggests that extracellular histones may constitute a novel target for therapeutic intervention in TLS when endothelial dysfunction occurs.

Primary hyperoxaluria: the adult nephrologist's point of view

In adults, primary hyperoxaluria (PH) does not always present as obviously as in children, leading to delayed or even missed diagnosis. When diagnosed in adulthood, PH usually progresses at a slower rate and the focus is on the prevention of recurrent kidney stones as much as it is on the preservation of renal function. The most tragic presentation is when the diagnosis is made after primary non-function of a renal graft for treating previously unknown renal disease. Recurrent stones, nephrocalcinosis and features of systemic oxalosis can all be presenting features. For these reasons, consideration should be given to screening for this rare condition, using biochemical and/or genetic means, but being careful to exclude common differential diagnoses. Such efforts should be synchronized with diagnostic methods for other rare kidney diseases.

Neural Network Analysis of Crystalluria Content to Predict Urinary Stone Type

Purpose

To investigate the relationship between urinary stone type and the type of crystals in the urine.

Patients and Methods

This retrospective study involved 485 patients with urinary stones treated at King Saud University Medical City from May 2015 to June 2017. Clinical data were obtained from medical records. Different statistical analysis methods were applied, including basic contingency analysis, analysis of variance, logistic regression, discriminant analysis, partition modeling, and neural network evaluations.

Results

Of 485 patients, 47 had crystals detected by urinalysis. The most common type of crystal was calcium oxalate (n = 31), which had the highest association with calcium oxalate stones. Uric acid crystals (n = 8) were associated with uric acid stones. The neural network model used for determining the sensitivity and specificity showed an R-square value of 0.88, with an area under the curve of 0.94 for calcium oxalate, 0.94 for carbonate apatite, and 1.0 for uric acid.

Conclusion

The predictive algorithm developed in the present study may be used with a patient's clinical parameters to predict the stone type. This approach predicts the stone types associated with certain patient characteristics with a high sensitivity and specificity, indicating that the models may be a valuable clinical tool in the diagnosis, management, and monitoring of stone diseases.

Kidney stone proteomics: an update and perspectives

INTRODUCTION

Main problems of kidney stone disease are its increasing prevalence and high recurrence rate after calculi removal in almost all areas around the globe. Despite enormous efforts in the past, its pathogenic mechanisms remain unclear and need further elucidations. Proteomics has thus become an essential tool to unravel such sophisticated disease mechanisms at cellular, subcellular, molecular, tissue, and whole organism levels.

AREAS COVERED

This review provides abrief overview of kidney stone disease followed by updates on proteomics for investigating urinary stone modulators, matrix proteins, cellular responses to different types/doses of calcium oxalate (CaOx) crystals, sex hormones and other stimuli, crystal-cell interactions, crystal receptors, secretome, and extracellular vesicles (EVs), all of which lead to better understanding of the disease mechanisms. Finally, the future challenges and translation of these obtained data to the clinic are discussed.

EXPERT OPINION

Knowledge from urinary proteomics for exploring the important stone modulators (either inhibitors or promoters) will be helpful for early detection of asymptomatic cases for prompt prevention of symptoms, complications, and new stone formation. Moreover, these modulators may serve as the new therapeutic targets in the future for successful treatment and prevention of kidney stone disease by medications or other means of intervention.

Urinary tract infections in culled sows from Greek herds: prevalence and associations between findings of histopathology, bacteriology and urinalysis

Background

Urinary tract infections (UTI) of sows characterized by cystitis, which may progress to ureteritis and pyelonephritis, can affect their productivity, longevity and welfare. In this study, we determined the prevalence of UTI by histopathology and bacteriology. Furthermore, we investigated possible associations between histologically confirmed cystitis and the results of urinalysis and urine cultures in culled sows from three farrow-to-finish herds in Greece.

Materials and methods

One hundred eighty-five routinely culled sows were included in the study. Their urinary bladder was collected from abattoirs and subjected to histopathology. Furthermore, urinalysis and urine cultures were performed on urine samples aseptically collected from the bladders.

Results

Histologically confirmed cystitis was evident in 85/185 (45.94%) culled sows. Among those, 44 (51.76%) suffered from acute and 41 (48.24%) from chronic inflammation. The majority of positive urine cultures were due to colonization of the urinary tract with E.coli, which accounted for 55.81% of the total cases, followed by Staphylococcus spp. which accounted for 18.60% of detected infections. Evidence of cystitis was associated with bacteriuria and sows with bacteriuria were 2.30 (P = 0.03, 95% CI: 1.10–4.83) times more likely to have histologically confirmed cystitis compared to sows with negative urine cultures. Bacteriuria was associated with proteinuria (P < 0.01, OR = 9.72, 2.63–35.88), increased urine pH (P < 0.01, 3.40, 1.10–10.56) and presence of sediment (P < 0.01, 6.00, 1.50–23.76) in urine. Sows with proteinuria had 9.72 (P < 0.01, 2.63–35.88) times higher odds of bacteriuria than those without. Histologically defined cystitis was associated with proteinuria (P < 0.01, 2.03–13.20) and decreased urine pH (P < 0.01, 0.13–0.72). Sows with proteinuria were 5.18 (P < 0.01, 2.03–13.2) times more likely to have histological lesions consistent with cystitis, than those without. For one unit increase in pH, it was 3.20 (P = 0.006, 1.39–7.69) times less likely for a sow to have chronic or acute cystitis compared to absence of cystitis.

Conclusion

In the studied population, UTI affected almost one out of two culled sows. Bacteriuria, which was more common among sows with UTI than those without, was mainly ascribed to members of the intestinal and environmental bacteria. Proteinuria and the existence of urine sediment which were associated with UTI, could be used as proxy traits for UTI in live sows.

Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) detection as a rapid and convenient screening test for cystinuria

BACKGROUND

Cystinuria is an inborn congenital disorder characterised by a defective cystine metabolism resulting in the formation of cystine stones. The Brand's test, used for diagnosis, requires dangerous substances, so has been replaced with high-performance liquid chromatography with fluorimetric detection (HPLC-FL). However, this technique requires the use of complex equipment. Infrared spectroscopy, universally used for stone analysis, recently was employed to detect insoluble cystine in urine. The aim of this study is to evaluate Infrared Spectroscopy combined with chemometric analysis as screening method to identify those patients requiring confirmation by HPLC-FL analysis.

METHODS

We examined 24 h urine specimens from 57 patients. The quantitative analysis was performed by HPLC-FL. The infrared spectroscopic urine sediment analysis was performed with an ATR accessory (ATR-FTIR). Urine is centrifuged, the supernatant is discarded, and the sediment is dried on to the ATR prism surface. Statistical analysis was performed using a custom-made software developed in MATLAB environment.

RESULTS

The HPLC-FL determination showed a normal excretion of cystine in 49 samples and an abnormal excretion in the remaining 8 samples. The ATR-FTIR analysis combined with a statistical approach gives a sensitivity of 1.0 and a specificity of 0.82 were obtained.

CONCLUSIONS

The introduction of the ATR-FTIR technique in our clinical laboratory setting may reduce time and cost analysis for diagnosis of cystinuria.

A study of crystalluria: effectiveness of including hygienic-dietary recommendations in laboratory reports

Objectives

To assess the effectiveness of incorporating hygienic-dietary recommendations in laboratory reports in reducing the incidence of renal colic (RC). A study was performed to compare the incidence of RC in two groups of patients who had suffered at least a crystalluria event associated with the risk of urolithiasis. Recommendations were only incorporated in the laboratory reports of one group.

Methods

A retrospective observational study. The study sample was composed of patients who had at least an episode of crystalluria associated with a higher risk of urolithiasis. The laboratory reports of patients in Group A (n=1,115), treated in 2017, did not include any hygienic-dietary recommendations, whereas patients in Group B (n=1,692), treated in 2018, received hygienic-dietary recommendations through their laboratory reports. χ² and Mann-Whitney U test were used to assess differences based on sex, age, and type of urinary crystals.

Results

The incidence of RC was 2.02 times higher in group A (2.24%) than in group B (1.12%). No significant differences were observed in the incidence of RC based on the type of urinary crystal. The incidence of RC was substantially higher in patients who suffered at least an event of crystalluria associated with a higher risk for urolithiasis as compared to the general population during the same period (0.46%, consistently with the incidence rates reported in the literature).

Conclusions

The incorporation of messages alerting on the risk of urolithiasis and the inclusion of hygienic-dietary recommendations in laboratory reports may be useful for reducing the incidence of RC.

Estimation of Urinary Nanocrystals in Humans using Calcium Fluorophore Labeling and Nanoparticle Tracking Analysis

Kidney stones are becoming more prevalent worldwide in adults and children. The most common type of kidney stone is comprised of calcium oxalate (CaOx) crystals. Crystalluria occurs when urine becomes supersaturated with minerals (e.g., calcium, oxalate, phosphate) and precedes kidney stone formation. Standard methods to assess crystalluria in stone formers include microscopy, filtration, and centrifugation. However, these methods primarily detect microcrystals and not nanocrystals. Nanocrystals have been suggested to be more harmful to kidney epithelial cells than microcrystals in vitro. Here, we describe the ability of Nanoparticle Tracking analysis (NTA) to detect human urinary nanocrystals. Healthy adults were fed a controlled oxalate diet prior to drinking an oxalate load to stimulate urinary nanocrystals. Urine was collected for 24 hours before and after the oxalate load. Samples were processed and washed with ethanol to purify samples. Urinary nanocrystals were stained with the calcium binding fluorophore, Fluo-4 AM. After staining, the size and count of nanocrystals were determined using NTA. The findings from this study show NTA can efficiently detect nanocrystalluria in healthy adults. These findings suggest NTA could be a valuable early detection method of nanocrystalluria in patients with kidney stone disease.

An Update on Evaluation and Management in Cystinuria

Cystinuria is the most common cause of inherited stone disease and is caused by the failure of absorption of filtered dibasic amino acids including cystine in the proximal tubules. It is associated with a very high recurrence rate in affected patients, with the potential for significant morbidity in such patients due to the need for repeated surgical interventions. A multimodal and multispecialty approach in a dedicated centre is the key to improving treatment outcomes and patient adherence to the treatment. This article reviews the latest knowledge on the clinical and diagnostic features and summarises key developments to aid clinicians in diagnosis and management options, together with future directions for the care of these patients.

Advances in the identification of calcium carbonate urinary crystals

The examination of the urinary sediment of a 64-year-old woman showed the presence of three different types of crystals, all with unusual morphology, which could not be identified with bright field microscopy, polarized light, and the knowledge of urine pH (7.5). The use of microscopic infrared spectroscopy, Raman spectroscopy and energy dispersive X-ray spectroscopy led to the identification of the three types of crystals as calcite, vaterite and aragonite, which are all variants of calcium carbonate crystals. This paper confirms the complex morphology and nature that urinary crystals may at times have and the utility of advanced infrared spectroscopy techniques for their identification.

Classification of Stones According to Michel Daudon: A Narrative Review

CONTEXT

Morphoconstitutional analysis of urinary stones is perhaps the most important examination in the evaluation of a patient with urolithiasis.

OBJECTIVE

A comprehensive stone classification system was developed in the early 1990s by Michel Daudon, which included the main types of stones and their possible physiopathogenic origin.

EVIDENCE ACQUISITION

A narrative review of the articles published about this classification was conducted, without time limit.

EVIDENCE SYNTHESIS

Two analytical steps are needed for the classification process: the microscopic examination, which gives the stone morphology, and the physical analysis, which provides the stone constitution. Upon completion of a full analysis, knowledge of the principal crystal species of the stone is acquired. In addition, this analysis highlights the possible causes of the lithogenic process, taking in account less frequent, but severe, pathologies.

CONCLUSIONS

The aim of this report is to summarize the principal etiological causes for urinary stone formation thanks to the morphoconstitutional analysis and to present its contribution in the field of urinary stones.

PATIENT SUMMARY

We looked at all types of stones and found that their origin varies according to the underlying pathology of the patient.

Urine and stone analysis for the investigation of the renal stone former: a consensus conference

The Consensus Group deliberated on a number of questions concerning urine and stone analysis over a period of months, and then met to develop consensus. The Group concluded that analyses of urine and stones should be routine in the diagnosis and treatment of urinary stone diseases. At present, the 24-h urine is the most useful type of urine collection, and accepted methods for analysis are described. Patient education is also important for obtaining a proper urine sample. Graphical methods for reporting urine analysis results can be helpful both for the physician and for educating the patient as to proper dietary changes that could be beneficial. Proper analysis of stones is also essential for diagnosis and management of patients. The Consensus Group also agreed that research has shown that evaluation of urinary crystals could be very valuable, but the Group also recognizes that existing methods for assessment of crystalluria do not allow this to be part of stone treatment in many places.

Anti-urolithiatic and anti-inflammatory activities through a different mechanism of actions of Cissus gongylodes corroborated its ethnopharmacological historic

ETHNOPHARMACOLOGICAL RELEVANCE

Species Cissus gongylodes has been used in the traditional medicine in South America and India for the treatment of urolithiasis, biliary and inflammatory problems without any scientific evidence.

AIM OF THE STUDY

This work was developed to investigate for the first time the anti-inflammatory and anti-urolithiatic activities of leaf decoction of C. gongylodes.

MATERIALS AND METHODS

Decoction was subjected to anti-inflammatory evaluation by the in vivo assay of ear oedema and quantification of the main mediators of inflammation PGE₂ and LTB₄, and the cytokine TNF-α. The decoction's anti-urolithiatic activity was determined by different in vitro assays to evaluate the inhibition and dissolution of the most prevalent types of kidney stones: calcium oxalate (CaOx) and struvite. Diffusion in gel technique and fresh urine of a patient with renal stone were used to investigate the inhibition and dissolution of CaOx, respectively, and the single diffusion gel growth technique was used to evaluate the inhibition and dissolution of struvite crystals. The decoction was chemically characterized by UHPLC-ESI-HRMS analysis.

RESULTS

Decoction showed in vivo anti-inflammatory activity by potent decreasing the level of both the main mediators of inflammation and dose-dependent in vitro anti-urolithiatic action by inhibition and dissolution of both type of crystals, CaOx and struvite.

CONCLUSIONS

Results obtained corroborate the reports of the traditional use of the decoction of Cissus gongylodes. Besides, it showed multi-target mechanisms actions, inhibition of the main inflammatory pathways, and inhibition/dissolution of the most prevalent types of crystals on urolithiasis. These actions make the decoction a promissory source to the development of new and more efficient drugs.

Dietary Oxalate Induces Urinary Nanocrystals in Humans

Introduction

Crystalluria is thought to be associated with kidney stone formation and can occur when urine becomes supersaturated with calcium, oxalate, and phosphate. The principal method used to identify urinary crystals is microscopy, with or without a polarized light source. This method can detect crystals above 1 μm in diameter (microcrystals). However, analyses of calcium oxalate kidney stones have indicated that crystallite components in these calculi are 50–100 nm in diameter. Recent studies have suggested that nanocrystals (<200 nm) elicit more injury to renal cells compared to microcrystals. The purpose of this study was to determine whether (i) urinary nanocrystals can be detected and quantified by nanoparticle tracking analysis (NTA, a high-resolution imaging technology), (ii) early-void urine samples from healthy subjects contain calcium nanocrystals, and (iii) a dietary oxalate load increases urinary nanocrystal formation.

Methods

Healthy subjects consumed a controlled low-oxalate diet for 3 days before a dietary oxalate load. Urinary crystals were isolated by centrifugation and assessed using NTA before and 5 hours after the oxalate load. The morphology and chemical composition of crystals was assessed using electron microscopy, Fourier-transform infrared spectroscopy (FTIR), and ion chromatography-mass spectrometry (IC–MS).

Results

Urinary calcium oxalate nanocrystals were detected in pre-load samples and increased substantially following the oxalate load.

Conclusion

These findings indicate that NTA can quantify urinary nanocrystals and that meals rich in oxalate can promote nanocrystalluria. NTA should provide valuable insight about the role of nanocrystals in kidney stone formation.

Laboratory changes during adrenocorticotropic hormone therapy associated with renal calcified lesions

BACKGROUND

Renal calcified lesions are known as one of the complications during adrenocorticotropic hormone (ACTH) therapy for intractable epilepsy. However, laboratory changes during the therapy or laboratory features of high-risk cases with renal calcified lesions are yet to be clarified.

METHODS

In this study, 43 patients with West syndrome aged ≤2 years were included. We retrospectively reviewed age and body mass index at the beginning of ACTH therapy, as well as the amount of fluid intake, daily urinary volume, and laboratory data during therapy. In addition, we studied the urinary sediment of the cases with renal calcified lesions diagnosed by computed tomography.

RESULTS

After initiating ACTH treatment, urinary calcium (Ca)/creatinine ratio and urinary pH increased within 2 weeks. Urinary crystals and renal tubular epithelial cells (RTECs) in urinary sediment were frequently found in most cases. Urinary Ca levels, proteinuria or frequency of urinary crystals, and number of RTECs in the urinary sediment were significantly higher in patients with epithelial casts (ECs) or hematuria than in patients without these findings. Among the seven patients who underwent abdominal CT, ECs or hematuria were found only in those with renal calcified lesions. These findings suggested that patients with ECs or hematuria were more likely to have calcified lesions.

CONCLUSIONS

The risk of renal calcified lesions increased after 2 weeks of ACTH treatment. Abnormal findings in urinary sediments might be an early sign of renal calcification during ACTH therapy.

Protective Effects of Epigallocatechin-3-Gallate from Green Tea in Various Kidney Diseases

Kidney diseases are common health problems worldwide. Various etiologies (e.g., diabetes, hypertension, drug-induced nephrotoxicity, infection, cancers) can affect renal function and ultimately lead to development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). The global rise in number of CKD/ESRD patients during recent years has led to tremendous concern to look for effective strategies to prevent or slow progression of CKD and ESRD. Natural compounds derived from herbs or medicinal plants have gained wide attention for scientific scrutiny to achieve such goals. One of such natural compounds that has been extensively investigated is epigallocatechin-3-gallate (EGCG), a major polyphenol found in the tea plant (Camellia sinensis). A growing body of recent evidence has shown that EGCG may be a promising therapeutic or protective agent in various kidney diseases. This article thus highlights recent progress in medical research on beneficial effects of EGCG against a broad spectrum of kidney diseases, including acute kidney injury, cisplatin-induced nephrotoxicity, kidney stone disease, glomerulonephritis, lupus nephritis, renal cell carcinoma, diabetic nephropathy, CKD, and renal fibrosis. The renoprotective mechanisms are also detailed. Finally, future perspectives of medical research on EGCG and its potential use in clinical practice for treatment and prevention of kidney diseases are discussed.

Development of a two-stage model system to investigate the mineralization mechanisms involved in idiopathic stone formation: stage 2 in vivo studies of stone growth on biomimetic Randall's plaque

Idiopathic stone formers often form calcium oxalate (CaOx) stones that are attached to calcium phosphate (CaP) deposits in the renal tissue, known as Randall's plaques (RP). Plaques are suggested to originate in the renal tubular basement membrane and spread into the interstitial regions where collagen fibrils and vesicles become mineralized; if the epithelium is breached, the RP becomes overgrown with CaOx upon exposure to urine. We have developed a two-stage model system of CaP-CaOx composite stones, consisting of Stage (1) CaP mineralized plaque, followed by Stage (2) CaOx overgrowth into a stone. In our first paper in this series (Stage 1), osteopontin (and polyaspartate) were found to induce a non-classical mineralization of porcine kidney tissues, producing features that resemble RP. For the Stage 2 studies presented here, biomimetic RPs from Stage 1 were implanted into the bladders of rats. Hyperoxaluria was induced with ethylene glycol for comparison to controls (water). After 4 weeks, rats were sacrificed and the implants were analyzed using electron microscopy and X-ray microanalyses. Differences in crystal phase and morphologies based upon the macromolecules present in the biomimetic plaques suggest that the plaques have the capacity to modulate the crystallization reactions. As expected, mineral overgrowths on the implants switched from CaP (water) to CaOx (hyperoxaluric). The CaOx crystals were aggregated and mixed with organic material from the biomimetic RP, along with some amorphous and spherulitic CaOx near the "stone" surfaces, which seemed to have become compact and organized towards the periphery. This system was successful at inducing "stones" more similar to human idiopathic kidney stones than other published models.

Performance evaluation of the new fully automated urine particle analyser UF-5000 compared to the reference method of the Fuchs-Rosenthal chamber

BACKGROUND

UF-5000 is the new fully automated urine particle analyser. We validated its performance.

METHODS

736 urines were analysed and results were compared by two pathologists on uncentrifuged samples, using Fuchs-Rosenthal chamber.

RESULTS

AUC of ROC curve ranged between 0.86 and 0.99. Sensitivity was >0.90 for all the elements and similar for RBC and yeasts. Specificity ranged between 0.74 and 0.89 for total cast, epithelial/non-squamous/renal-tubular cells and RBC. For all the other parameters specificity was >0.90. Comparison with Fuchs-Rosenthal chamber was very good for all the parameters; r ranged between 0.52 and 0.99 except for pathological cast because of the lack of the pathological samples in medium and higher ranges. Linearity performance (R²) was 1.00, 1.00 and 0.99 respectively for RBC, WBC and epithelial cells (EC). No carry-over was observed. The within-run imprecision was 25.42%,13.81%,1.36% for RBC; 37.50%,10.16%,1.41% for WBC and 35.25%, 17.85%,6.30% for EC at low, near the cut off level and high concentrations, respectively. The between-run imprecision was 6.90%,1.60% for RBC, 4.10%,1.90% for WBC and 7.60%,7.30% for EC, using low and high positive quality controls, respectively.

CONCLUSION

UF-5000 is an analyser of great interest to detect urine particle related to pathological process of kidney and urinary tract.