Stone Components Research Articles

Compositional analysis of naive and recurrent urinary calculus by infrared spectroscopy

Objective To explore rate of recurrent urinary calculus in patients received infrared spectroscopy and diet intervention. Methods A total of 1136 patients with urolithiasis diagnosed in our hospital from January 2017 to June 2017 were selected as the research subjects. Infrared spectroscopy analysis system was performed to analyze the stone components of all the patients. All of them were divided into two group(observation group and control group). Observation group contained 703 patients who underwent diet intervention based on the analysis results of the stone main components. Other patients were not altered their dietary habit. The probability of disease recurrence, re-operation and main components changing of two groups 12 months after discharge was compared. Results The objective of the present study was to retrospective review 1136 patients with calculus who were divided into two groups. Observation group included 703 patients and control group got the rest. There were 85 patients formed calculus after surgery in observation group, 42 of that needed re-operation. Ninety-six patients recurred urinary calculus in control group, 68 of that came back to hospital for urinary after the first time. The rate of recurrence and re-operation in observation group were lower(12.09 % vs.22.17 %, χ2=9.595, P=0.002; 5.97 % vs.15.07 %, χ2=9.595, P=0.002 ). Changing of main calculus components occurred 14 patients of 42 in observation group. The same variation appeared 7 patients of 68 in control group. The rate of main components changing in observation group was lower(χ2=8.922, P=0.005). Conclusions After the surgery of urolithiasis, appropriate diet plan according to stone composition analysis by infrared spectroscopy will reduce the formation of urinary stones by controlling the intake of calcium-containing foods, so that the recurrence and re-operation rate will drop significantly after discharge. Key words: Urinary Calculi; Infrared Rays; Feeding Behavior

Development of a Humanized Murine Model for the Study of Oxalobacter formigenes Intestinal Colonization.

Oxalobacter formigenes are bacteria that colonize the human gut and degrade oxalate, a component of most kidney stones. Findings of clinical and epidemiological studies suggest that O. formigenes colonization reduces the risk for kidney stones. We sought to develop murine models to allow investigating O. formigenes in the context of its native human microbiome. For humanization, we transplanted pooled feces from healthy, noncolonized human donors supplemented with a human O. formigenes strain into recipient mice. We transplanted microbiota into mice that were treated with broad-spectrum antibiotics to suppress their native microbiome, were germ free, or received humanization without pretreatment or received sham gavage (controls). All humanized mice were stably colonized with O. formigenes through 8 weeks after gavage, whereas mice receiving sham gavage remained uncolonized (P < .001). Humanization significantly changed the murine intestinal microbial community structure (P < .001), with humanized germ-free and antibiotic-treated groups overlapping in β-diversity. Both germ-free and antibiotic-treated mice had significantly increased numbers of human species compared with sham-gavaged mice (P < .001). Transplanting mice with human feces and O. formigenes introduced new microbial populations resembling the human microbiome, with stable O. formigenes colonization; such models can define optimal O. formigenes strains to facilitate clinical trials.

Composition analysis and related risk factors of recurrent upper urinary tract calculi

Objective To analyze the composition and risk factors of recurrent upper urinary tract calculi. Methods From September 2015 to December 2017, 120 cases of recurrent upper urinary calculi in our hospital were selected.The clinical data of all the subjects were analyzed retrospectively.The changes of stone components before and after the recurrence of calculi were analyzed, and the risk factors for the changes of recurrent stones were evaluated. Results Recurrent upper urinary calculi in 120 cases, calcium oxalate stone in 50 cases, calcium phosphate stone in 24 cases, infectious stone in 20 cases, uric acid stone in 10 cases, and cystine stone in 16 cases were found. Eighty patients had unchanged stone composition and 40 patients had changes in stone composition.Patients with recurrent upper urinary tract stones were closely related to stone type, recurrence time and other factors.The difference was statistically significant(P<0.05). Conclusions The main changes of calculus in recurrent urinary calculi are the conversion of calcium oxalate stones and infectious stones.The main risk factors for the change of stone composition are the time of recurrence.Patients with recurrent stone for more than 5 years or less than 1 year need to be rechecked regularly. Key words: Urinary Calculi; Risk Factors

Effects of physical properties of nano-sized hydroxyapatite crystals on cellular toxicity in renal epithelial cells

Hydroxyapatite (HAP) is not only a common component of most idiopathic CaOx stones, but also the core of Randall's plaque. HAP is a nest that can induce the formation of Randall's plaques and even kidney stones. We studied the toxic effects and mechanisms of four different types of nano-HAP crystals (H-Sphere, 72.5 nm × 72.5 nm; H-Needle, 37.2 nm × 162.7 nm; H-Rod, 42.3 nm × 115.3 nm; and H-Plate, 145.5 nm × 272.9 nm) on human renal proximal tubular epithelial cells (HK-2). HAP crystals could cause oxidative stress that triggered a series of cell dysfunction problems, resulting in decreased cell viability, loss of cell membrane integrity, cell swelling, and cell necrosis. The toxic effect of HAP was mainly attributed to its entry into cell by endocytosis and its accumulation in the lysosomes, causing the level of intracellular reactive oxygen species (ROS) to rise, the mitochondrial membrane potential (Δψm) to decrease, the lysosomal integrity to be destroyed, and the cell cycle blocked during the G0/G1 phase. The cytotoxicity of the four kinds of HAP crystals was ranked as follows: H-Sphere > H-Needle > H-Rod > H-Plate. The cytotoxicity of each crystal was positively correlated with low absolute zeta potential, conduciveness to internalized morphology, large specific surface area and aspect ratio, and small particle size. These results indicated that nano-HAP could damage HK-2 cells, and the physical properties of HAP crystals play a vital effect in their cytotoxicity.

The observation of the effect of sodium potassium citrate on prolonging the retention time of double J tube in vivo

Objective To explore the effect and mechanism of the extension of double-J tube in vivo retention time with sodium potassium citrate. Methods From March 2015 to July 2017, a total of 86 cases who underwent postoperative indwelling double-J tube for long time were selected. All patients were randomly divided into experimental and control groups, the experimental group with oral sodium potassium citrate postoperatively and the control group without special treatment. The differences of urinary scale and calculus of double-J tube were observed in 2, 4 and 6 months after catheterization, and the difficulty of tube extraction was determined. Results Indwelling double-J tube for 2 months, the double-J tube incidence rate of pulling out hard in the experimental group was 2.5%, the incidence rate in the control group was 2.2%, there was no statistical significant difference (P>0.05). Indwelling tube for 4 months, the incidence rate was 5.0% in the experimental group, and 9.1% for the control group.Indwelling tubes for six months, the incidence rate was 10.0% in the experimental group and 15.9% for the control group.The difference had statistical significance (P<0.01). The incidence rate of double-J tube wall stones was 80% in the experimental group, and 89.1% in the control group. The difference was statistically significant. Calcium oxalate and phosphate stones were the main components of the wall stones. Conclusions The difficulty to pull out of the double-J tube is positively correlated with the retention time in the body. Potassium sodium hydrogen citrate can significantly reduce the formation of calcium oxalate and phosphate stones in double-J tube wall, thus prolonging the retention time of double-J tube in vivo and reducing the difficulty of extubation. Key words: Catheters, Indwelling; Sildenafil Citrate

Kidney stone compositions and frequencies in a Norwegian population

Objectives: The aim of this study was to investigate frequencies of kidney stone constituents in a Norwegian population and examine trends over time by comparing with an earlier study of this population.Materials and methods: Upper urinary tract calculi consecutively collected from patients who underwent stone surgery at Akershus University Hospital from July 2014 to December 2017, in total 1252 calculi, were analysed by infrared spectroscopy. The results were compared with a study of 500 calculi collected from June 1975 to September 1980 at the same hospital.Results: The male:female ratio was 1.83:1. Single-component stones constituted 39%, 35% were binary, and 25% ternary. Main stone component frequencies were oxalate 71.3%, calcium oxalate monohydrate 53.7% with higher occurrence in males, calcium oxalate dihydrate 17.6%, carbonate apatite 10.8% and struvite 5.7%, both with higher occurrence in females, uric acid 8.9% with a non-significant male predominance, brushite 1.6% and cystine about 1%. Over four decades the frequency of UA stones increased by 4.6-times, whereas struvite and pure carbonate apatite stones decreased and no change was observed for brushite stones.Conclusion: Frequencies of kidney stone types in this Norwegian population are mainly in accordance with other studies, except a large increase in UA stones over four decades, partly caused by a particularly low frequency of UA stones in the old study, a decreased carbonate apatite frequency over four decades, and an unaltered brushite frequency. Also, in contrast to other studies, a relatively small and non-significant male UA stone predominance was found.

Morphological characteristics and microstructure of kidney stones using synchrotron radiation μCT reveal the mechanism of crystal growth and aggregation in mixed stones.

Understanding the mechanisms of kidney stone formation, development patterns and associated pathological features are gaining importance due to an increase in the prevalence of the disease and diversity in the presentation of the stone composition. Based on the microstructural characteristics of kidney stones, it may be possible to explain the differences in the pathogenesis of pure and mixed types of stones. In this study, the microstructure and distribution of mineral components of kidney stones of different mineralogy (pure and mixed types) were analyzed. The intact stones removed from patients were investigated using synchrotron radiation X-ray computed microtomography (SR-μCT) and the tomography slice images were reconstructed representing the density and structure distribution at various elevation planes. Infrared (IR) spectroscopes, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to confirm the bulk mineral composition in the thin section stones. Observations revealed differences in the micro-morphology of the kidney stones with similar composition in the internal 3-D structure. Calcium oxalate monohydrate stones showed well-organised layering patterns, while uric acid stones showed lower absorption signals with homogenous inner structure. Distinct mineral phases in the mixed types were identified based on the differential absorption rates. The 3-D quantitative analysis of internal porosity and spatial variation between nine different types of stones were compared. The diversity among the microstructure of similar and different types of stones shows that the stone formation is complex and may be governed by both physiological and micro-environmental factors. These factors may predispose a few towards crystal aggregation and stone growth, while, in others the crystals may not establish stable attachment and/or growth.

The relationship between visceral fat area and uric acid stone formation

Objective To investigate the relationship between uric acid stone formation and visceral fat area based on computed tomography. Methods As many as 247 patients admitted to our hospital were retrospectively reviewed from January 2017 to January 2018. There were 161 males (65.2%) and 86 females (34.8%). The average age was 51 (20-88 years). According to the results of stone analysis after surgery, the patients were divided into uric acid stone group and non-uric acid stone group. According to the abdominal CT scan, Image J software was used to measure the anthropometric measurements like waist circumference, total fat area (TFA), and visceral fat area (VFA), and subcutaneous fat area (SFA). The clinical characteristics of different stone components were compared. An univariate and multivariate logistic regression analysis was used to identify the independent factors associated with uric acid stone formation. Different anthropometric measurements were compared by using the area under receiver operating characteristic curve. Results The uric acid stones in high VFA group (28/110; 25.5%) were obviously more frequent than that in the low VFA group (7/137; 5.1%) (P<0.05). The results of the univariate logistic regression analysis showed that age, diabetes, hyperlipidemia, TFA, waist circumference, body mass index (BMI), VFA, uric acid, and urine pH were statistically significant (P<0.05). Multivariate logistic regression analysis revealed that diabetes (OR=3.408, 95%CI 1.123-10.340, P=0.030), VFA (OR=6.740, 95%CI 1.951-23.279, P=0.003), uric acid (OR=3.182, 95%CI 1.120-9.040, P=0.030) and urine pH (OR=4.052, 95%CI 1.095-14.989, P=0.036) were independent factors associated with uric acid stone formation. The area under the curve of TFA, waist circumference, BMI, VFA, and SFA were 0.659, 0.665, 0.632, 0.723 and 0.544, respectively. Conclusions Diabetes, VFA, uric acid and urine pH are independent factors influencing the formation of uric acid stones. Compared with other anthropometric measurements such as TFA, waist circumference, BMI, and SFA, VFA can better assess abdominal obesity and predict the formation of uric acid stones. Key words: Visceral fat area; Uric acid stone; Metabolic syndrome; Abdominal obesity

The Potential Use of Oyster Shell Waste in New Value-Added By-Product

Calcium carbonate is one of the most used raw materials in various industries, such as construction materials, food supplement, pharmaceutics, animal feed, plastic production, and others. Calcium carbonate can derive from marine wastes, like crustaceans and bivalve’s shells. The worldwide demand for new sources of food has increased exponentially, and following that tendency, the mariculture—especially the oyster culture—has been increasingly resorting to farming techniques. In 2016, 438 billion tons of oysters were produced. The majority of the shells were unduly discarded, presenting a public health problem. This article offers a solution based on the reuse and recycling of oyster shell residues in the production region of Florianópolis, SC, Brazil. The presented solution is an oyster shell by-product developed by a local company which produces artificial stone. The main component of the artificial stone is a composite material made of oyster shells incorporated in a polymeric resin. The mechanical properties, such as its flexural strength, hardness, Weibull modulus, and fracture analysis, were held in the artificial stone. The mechanical results of the new artificial stone were compared with other natural stones, such as granite and marble, and other commercial artificial stones. This material owns suitable mechanical properties for table tops and workbenches. Using this product as an artificial stone represents an innovation in the development of a new product and adds commercial value to local waste. This product is an excellent example of a circular economy for local producers who care about the environment, and it encourages the reduction of extraction of natural stone, such as granite and marble.

Formation of Poorly Crystalline and Amorphous Precipitate, a Component of Infectious Urinary Stones: Role of Tetrasodium Pyrophosphate

The present study concerns an important topic regarding the search for new, improved, and effective methods of preventing the development of infectious urinary stones. In this article, the effect of tetrasodium pyrophosphate (TSPP) on the formation of a poorly crystalline and amorphous precipitate in artificial urine in the context of infectious urinary stone formation is studied. The spectrophotometric results suggest that TSPP presence shifts the formation of the poorly crystalline and amorphous precipitate (PCaAP) toward lower pH, which means that PCaAP is formed earlier. In other words, TSPP promotes the formation of PCaAP. Additionally, TSPP causes the formation of calcium pyrophosphate. These results are confirmed by X-ray diffraction and energy dispersive X-ray studies. The experimental results obtained are explained on the basis of theoretical chemical speciation analysis of chemical complexes formed in artificial urine.

Structure and cleavage of monosodium urate monohydrate crystals.

The structural study of monosodium urate monohydrate, as the principal component in gout stones, reveals that a simple and biocompatible way to break down the crystals into polymerised molecules at pH 7.4 (the acidity of normal human blood) is to peel them off along the [001] direction by sonication.

Obesity and stones.

The incidence of urolithiasis has shown a prominent increase in the last two to three decades and evidence-based data have clearly indicated the certain role of obesity and overweight in both children and adults. As a certain component of metabolic syndrome, 'obesity' has been found to have a significant impact on the urinary metabolic risk factors which may be important in stone formation. In this present review article, we aimed to evaluate the possible association between obesity and urolithiasis and related risk factors. The epidemiology, pathophysiology, and management of stone disease in obese cases will be discussed in detail. The possible influence of overweight/obesity on the metabolic stone-forming risk factors has been subjected to several studies which in turn well demonstrated the increased risk of stone formation in this population. Although the exact underlying mechanisms are still to be outlined, some certain pathogenetic factors, namely, changes in urinary pH and increased excretion of some urinary stone components have been well demonstrated. Given this increased risk status, these cases require a more comprehensive workup for urolithiasis. Appropriate metabolic evaluation-based medical therapy alongside dietary recommendations will be effective in preventing stone formation. Patients suffering from obesity problem have particular risk factors for urolithiasis when compared with their normal-weight counterparts. All efforts should be taken to increase the awareness of this problem and necessary precautions with well-planned treatment plan are the main tasks for urologists.

Quantification and differentiation of composition of mixed pancreatic duct stones using single-source dual-energy CT: an ex vivo study

PurposeTo evaluate the feasibility of using single-source dual-energy CT (SS DECT) to quantify and differentiate calcium carbonate (CA) and non-calcium carbonate (NCA) components of pancreatic duct stones (PDS) with mixed composition.Materials and methodsA total of 12 PDS harvested from general surgery department in our hospital were analyzed with micro-CT as a reference standard for CA and NCA composition. These stones were placed in a TOS water phantom of 35 cm diameter to simulate standard adult body size. High- and low-energy image sets were acquired from SS DECT scans with high/low tube potential pairs of 80 kVp/140 kVp. All the image sets were imported into an in-house software for further post-processing. CT number ratio (CTR), defined as the ratio of the CT number at 80 kVp to 140 kVp was calculated for each pixel of the images. Threshold was preset between 1.00 and 1.25 to classify CA and NCA components. Pixels in PDS with CTR higher than the threshold were classified as CA, and those with CTR lower than the threshold were classified as NCA. The percentages of CA and NCA for each stone were determined by calculating the number of CA and NCA pixels. Finally, the minimal, maximal and root-mean-square errors (RMSE) of composition measured by SS DECT under each threshold were calculated by referring to the composition data from micro-CT. The optimal threshold was determined with the minimal RMSE. A paired t test was used to compare the stone composition determined by DECT with micro-CT.ResultsThe optimal CTR threshold was 1.16, with RMSE of 6.0%. The minimum and maximum absolute errors were 0.22% and 11.35%, respectively. Paired t test showed no significant difference between DECT and micro-CT for characterizing CA and NCA composition (p = 0.414).ConclusionSS DECT is a potential approach for quantifying and differentiating CA and NCA components in PDS with mixed composition.

Impact of bacteria on aggregation of crystalline and amorphous components of infectious urinary stones

Infectious urinary stones consist of an agglomerate of bacteria, highly crystalline struvite, and poorly crystalline and amorphous precipitate (PCaAP). The paper describes an experimental study on the agglomeration of PCaAP in the presence and absence of bacteria of the Proteus mirabilis species, in which blind studies are done with bacterial macromolecules with and without lipopolysaccharide. The formation of struvite is avoided by using Mg-free artificial urine. Optical microscopy methods and zeta potential measurements both confirm that the bacterial lipopolysaccharides are the key factors promoting agglomeration, besides the bacterially induced pH change which leads to precipitation in the first place.

Variation in Kidney Stone Composition Within the United States

Kidney stone incidence has been known to vary with temperature and climate. However, little is known about any variation in the composition of kidney stones across different regions of the United States. We attempted to evaluate whether stone composition changes depending on region. We were given access to de-identified data from LABCORPs database of kidney stone composition from August 1, 2016, to October 24, 2016, for states in seven representative areas of the country: Virginia, Minnesota, Florida, Arizona, Colorado, California, and Texas. We analyzed each component of kidney stones with optical microscopy supplemented with Fourier-transform infrared spectroscopy (FT-IR) spectrometry using both the percentage of the stone that was composed of that component as well as a binary variable coded none vs any. Univariate associations between component and state were examined using chi-square or Fisher's exact test for the binary indicator, and analysis of variance for the continuous percentage. The same set of analyses was used for decade of age vs each component. The association between age and state was examined using analysis of variance. Data were available for 4335 kidney stones, from patients in the 7 states mentioned. The most common components across all stones were calcium oxalate monohydrate and calcium phosphate (both present in 93% of stones), calcium oxalate dihydrate (in 57% of stones), and uric acid (in 12% of stones). Stone composition did not vary widely across regions, except for uric acid stones, which were more prevalent in Florida compared to other states, with an odds ratio of 1.43 (95% confidence interval 1.12, 1.83). Kidney stone composition does not vary widely by region within the United States. Although temperature and humidity play a role in stone incidence, there does not appear to be a large variation between different climates, with the exception of uric acid stone formation in Florida.

Endothelium corneum gigeriae galli extract inhibits calcium oxalate formation and exerts anti-urolithic effects

Ethnopharmacological relevanceTraditional Chinese Medicine is preferred because of its safety and minimal/reduced side effects. Endothelium Corneum Gigeriae Galli (ECGG) extract, a traditional Chinese drug consisting of the dried gizzard membrane of Gallus gallus domesticus Brisson, was assessed for its effects and mechanism on urolithiasis. Aims of studyTo evaluate the effects of ECGG extract on calcium oxalate (CaOx) crystal formation in vitro, and assess the anti-urolithic effects of ECGG extract in vivo and explore the underlying mechanism. Materials and methodsIn vitro, CaOx crystals were treated with ECGG extract (0.05, 0.2, and 0.8 g/mL), and assessed by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction and electrical conductivity. Then, a rat model of renal calculi was established by ethylene glycol and ammonium chloride treatment, and ECGG extract (5.0, 10.0 and 20.0 g/kg) was administered orally. After treatment, urine, serum and kidney bioindicators were analyzed, as well as kidney's pathological features. ResultsIn the presence of ECGG extract, calcium oxalate dihydrate (COD) crystals with typical tetragonal bipyramidal morphology were obtained; meanwhile, the formation of calcium oxalate monohydrate (COM), a major urinary stone component, was inhibited; in addition, the equilibration time of the chemical reaction of Ca2+ and C2O42− ions was delayed in a concentration dependent manner. ECGG extract actually showed anti-urolithic effects; the incidence rates of crystal formation in the kidney in the model, low, middle and high dose groups were 100%, 90%, 70% and 60%, respectively, with a dose-dependent alleviation of kidney stone amounts and kidney damage. Treatment with middle and high ECGG extract doses significantly decreased urine uric acid and oxalic acid amounts, serum creatinine, urea nitrogen and uric acid contents, and kidney tissue oxalic acid and calcium levels, while increasing kidney and urinary magnesium and superoxide dismutase levels (P < 0.05). ConclusionECGG extract has outstanding anti-urolithic effects, potentially with included bioorganic molecules inducing COD crystal nucleation and growth. Therefore, ECGG extract is a promising drug for preventing and treating urolithiasis.

Water Structure, Dynamics and Ion Adsorption at the Aqueous {010} Brushite Surface

Understanding the growth processes of calcium phosphate minerals in aqueous environments has implications for both health and geology. Brushite, in particular, is a component of certain kidney stones and is used as a bone implant coating. Understanding the water–brushite interface at the molecular scale will help inform the control of its growth. Liquid-ordering and the rates of water exchange at the brushite–solution interface have been examined through the use of molecular dynamics simulation and the results compared to surface X-ray diffraction data. This comparison highlights discrepancies between the two sets of results, regardless of whether force field or first principles methods are used in the simulations, or the extent of water coverage. In order to probe other possible reasons for this difference, the free energies for the adsorption of several ions on brushite were computed. Given the exothermic nature found in some cases, it is possible that the discrepancy in the surface electron density may be caused by adsorption of excess ions.

Investigation of the long-term stability of quartzite and basalt for a potential use as filler materials for a molten-salt based thermocline storage concept

Solar thermal power plants with integrated thermal storage are candidates for renewable energy production concepts. For cost reduction of thermal energy storage a single tank concept, the so called thermocline storage concept, instead of the two-tank molten salt thermal storage is as promising cost reduction option. Further cost reductions in the thermocline storage are expected by replacing a significant amount of Solar Salt by a low cost filler material. Such filler materials have to be stable in molten salt at temperatures up to 560 °C. In this work degradation studies on quartzite and basalt types in molten salt are carried out after a preselection has been published elsewhere recently. The investigations are focused on the compatibility of natural stones with Solar Salt, a mixture of sodium nitrate and potassium nitrate, as common heat storage material.This work addresses changes of the molten salt properties and in the microstructure of the natural stones depending on the exposure time in molten salt at temperatures of approximately 560 °C. In the first step of the material investigation the natural stones were isothermally stored in Solar Salt at a maximum temperature of 560 °C for up to 10.000 h. After the thermal treatment the microstructure of the stones was investigated by QEMSCAN (Quantitative Evaluation of Minerals by Scanning electron microscopy). By means of this analysis method the changes in the microstructure of quartzite and basalt was detected and arising stone components are identified. The melting temperature und enthalpy of Solar Salt was measured and compared with the salt properties before the thermal treatment. Additionally, the specific heat capacities of basalt and quartzite depending on the temperature were determined. The results are essential to verify the suitability of quartzite and basalt as potential filler materials in modern thermocline storage concepts.

Composition of urinary tract stones formed by children in two populations in the Uyghur region of China

BackgroundTo retrospectively compare the composition of urinary tract stones formed by Uyghur children from the southern (Kashgar) and northern (Urumchi) parts of the Xinjiang region. MethodsThe chemical composition of urinary tract calculi formed by 855 Uyghur children from the two regions in Xinjiang (366 Kashgar and 489 Urumchi) was compared retrospectively. Stone composition was determined by infrared spectroscopy. Factors that might have been of relevance for the findings such as age, gender, stone location and geographic region were also considered. ResultsKashgar children were younger than Urumchi children (2.8 ± 2.7 vs. 4.3 ± 3.7 years, p < 0.001). Although ammonium urate was the dominant stone component in the whole population, calcium oxalate was most common in children from Urumchi. The mean occurrence of ammonium urate, calcium oxalate and uric acid differed significantly between stones formed by Kashgar and Urumchi children (52.5% vs. 29.2%, 18.9% vs. 29.4%, 12.3% vs. 20.9%; respectively, p < 0.001). Renal stones were less frequently recorded in Kashgar children than in Urumchi children (65.8% vs. 91.6%, p < 0.001). Interestingly, bladder stones were more common in children from Kashgar (28.4% vs. 3.7%; p < 0.001). ConclusionUyghur children from the southern part of Xinjiang apparently had a more serious form of stone disease than children from the northern part and the occurrence of stones dominated by ammonium urate stones was extremely high in children from the southern part of the region.

High prevalence of pediatric urinary tract stones in Xinjiang Uyghur.

The aim of the study was to report the characteristics of urolithiasis in Uyghur patients from Xinjiang, China. The composition of stones collected from 1863 patients in the Uyghur region of Xinjiang was analyzed. The median age of patients was 17years [25th and 75th percentiles: 2, 36]. The stones were delivered by 1299 males (69.7%) and 564 females (30.3%). Calcium oxalate was the predominant stone component in 42.1% of the patients, followed by ammonium urate in 20.6%. Females had formed more stones of magnesium ammonium phosphate 8.9 vs. 5.6% (p = 0.010) and carbonate apatite 6.2 vs. 3.3% (p = 0.004). In contrast uric acid was more common in males than in females; 21.6 vs. 15.1% (p = 0.001). In this series, pediatric patients (age range 0-18) were more likely to present with a stone (51.5%, p < 0.001). Moreover, the largest number of pediatric stones was recorded in children 1-2years old (37.9%, p < 0.001). The occurrence of ammonium urate stones was extremely high (52.4%) in children with an age below 1year. There was a downward trend for ammonium urate with age in both children and adults (p for trend < 0.001, respectively). In contrast the frequency of uric acid declined with age in pediatric patients, but increased in adults (p for trend < 0.001, respectively). This study provides a basis for further considerations on the management of Xinjiang Uyghur patients and emphasize the severity of pediatric stone problems.