Spectrum of stone composition: structural analysis of 1050 upper urinary tract calculi from northern India

Unlocking the Potential of Silver Nanoparticles: From Synthesis to Versatile Bio-Applications

Silver nanoparticles (AgNPs) are leading the way in nanotechnological innovation, combining the captivating properties of silver with the accuracy of nanoscale engineering, thus revolutionizing material science. Three main techniques arise within the alchemical domains of AgNP genesis: chemical, physical, and biological synthesis. Each possesses its distinct form of magic for controlling size, shape, and scalability-key factors necessary for achieving expertise in the practical application of nanoparticles. The story unravels, describing the careful coordination of chemical reduction, the environmentally sensitive charm of green synthesis utilizing plant extracts, and the precise accuracy of physical techniques. AgNPs are highly praised in the field of healthcare for their powerful antibacterial characteristics. These little warriors display a wide-ranging attack against bacteria, fungi, parasites, and viruses. Their critical significance in combating hospital-acquired and surgical site infections is highly praised, serving as a beacon of hope in the fight against the challenging problem of antibiotic resistance. In addition to their ability to kill bacteria, AgNPs are also known to promote tissue regeneration and facilitate wound healing. The field of cancer has also observed the adaptability of AgNPs. The review documents their role as innovative carriers of drugs, specifically designed to target cancer cells with accuracy, minimizing harm to healthy tissues. Additionally, it explores their potential as cancer therapy or anticancer agents capable of disrupting the growth of tumors. In the food business, AgNPs are utilized to enhance the durability of packing materials and coatings by infusing them with their bactericidal properties. This results in improved food safety measures and a significant increase in the duration that products can be stored, thereby tackling the crucial issue of food preservation. This academic analysis recognizes the many difficulties that come with the creation and incorporation of AgNPs. This statement pertains to the evaluation of environmental factors and the effort to enhance synthetic processes. The review predicts future academic pursuits, envisioning progress that will enhance the usefulness of AgNPs and increase their importance from being new to becoming essential within the realms of science and industry. Besides, AgNPs are not only a subject of scholarly interest but also a crucial component in the continuous effort to tackle some of the most urgent health and conservation concerns of contemporary society. This review aims to explore the complex process of AgNP synthesis and highlight their numerous uses, with a special focus on their growing importance in the healthcare and food business sectors. This review invites the scientific community to explore the extensive possibilities of AgNPs in order to fully understand and utilize their potential.

Decoding Urinary Stones: Compositional Insights and Recurrence Patterns from a Tertiary Care Hospital in Eastern India

Background and objective Urinary stones are a prevalent medical condition entailing significant health burdens and substantial financial ramifications. Its global prevalence is expected to rise notably, particularly in low-middle-income nations. Understanding the spectrum of diverse urinary stone types is crucial for effective management and prevention. This study aims to elucidate the demographic profiles, clinical types, and recurrence of urinary stone cases at a tertiary care hospital in Eastern India. Methods and materials The clinical data from the electronic medical record of 1,231 patients with urolithiasis who underwent surgery in a tertiary care center in eastern India from January 2015 to November 2022 were retrospectively analyzed. Patient data, including demographic information, clinical records, dietary habits, water intake, and stone recurrence history, were collected. A thorough statistical analysis was conducted to elucidate the associations between patient characteristics, urinary stone composition, and recurrence. Results Among the 1,231 participants, the majority of cases (343 (27.9%)) were in the 31-40 age group, with a higher prevalence in males (876 (71.2%)) than in females (355 (28.8%)). Flank pain or abdominal pain (593 (48.1%)) was the primary complaint, followed by nausea/vomiting (227 (18.5%)). Most stones (922 (74.9%)) were located in the kidney, and calcium oxalate was the predominant stone component (773 (62.8%)). The highest stone recurrence rates were in patients aged between 21-30 years (21 (36.8%)) and 31-40 years (16 (28.0%)). A low non-vegetarian diet and adequate hydration may reduce the likelihood of stone recurrences. Conclusion This study provides insights into the compositional analysis of urinary stones in the eastern Indian population, addressing the causes of their recurrence and management strategies, which are crucial for prevention and effective management. The findings indicate that the early middle-aged group exhibited the highest incidence of urinary stones. We also observed that strict adherence to a low animal protein, along with proper hydration and lifestyle changes, significantly reduced urinary stone recurrence.

Assessment of Urinary Stone Chemical Compositions and Prevalence of Metabolic Disorders Among Urolithiasis Patients in Northern Sri Lanka: A Prospective Study

Introduction Urolithiasis, a common urological disorder affecting the global population, demonstrates geographical diversity due to factors such as water quality, climate variations, health conditions, and dietary habits. This study, conducted in Northern Sri Lanka, examines urinary stone compositions and assesses the prevalence of metabolic disorders among urolithiasis patients. Methods This prospective cross-sectional study, conducted at Jaffna Teaching Hospital, Jaffna, Sri Lanka, from July 2022 to June 2023, focused on surgically treated urolithiasis patients. Institutional ethical clearance was obtained. Patient details and investigational findings were collected through questionnaires and data extraction forms. Stone analysis utilized Fourier transform infrared spectroscopy, and a detailed metabolic evaluation of a 24-hour urine collection sample was carried out. Results This study followed 153 surgically treated urolithiasis patients, primarily male (64.3%), with a mean age of 48.64. Ureteric colic (48.4%) was common, with kidney stones (45.8%) prevalent; 57.52% had recurrent stones. Diabetes mellitus (DM; 23.5%) was the top comorbidity. Calcium oxalate monohydrate (COM) stones (78.4%) were the most frequent, followed by uric acid (12.4%). COM predominated in the 40-59 age group. There was no significant gender-stone type association. A total of 86.9% had metabolic abnormalities, notably hypocitraturia (60.1%). Moreover, 23% had both hypocitraturia and hypomagnesuria. Some metabolic disorders showed gender differences, with a marginal age-metabolic disorder association (p < 0.061). Urine oxalate levels were normal, with higher variability in males. Conclusion Middle-aged males with urolithiasis commonly presented with ureteric colic and predominantly had COM stones. Recurrent stones were common, often accompanied by metabolic abnormalities such as hypocitraturia and hypomagnesuria, with DM as the primary comorbidity.

High-energy X-ray diffraction experiment employing a compact synchrotron X-ray source based on inverse Compton scattering

X-ray diffraction (XRD) is an important material analysis technique with a widespread use of laboratory systems. These systems typically operate at low X-ray energies (from 5 keV to 22 keV) since they rely on the small bandwidth of K-lines like copper. The narrow bandwidth is essential for precise measurements of the crystal structure in these systems. Inverse Compton X-ray source (ICS) could pave the way to XRD at high X-ray energies in a laboratory setting since these sources provide brilliant energy-tunable and partially coherent X-rays. This study demonstrates high-energy XRD at an ICS with strongly absorbing mineralogical samples embedded in soft tissue. A quantitative comparison of the measured XRD patterns with calculations of their expected shapes validates the performance of ICSs for XRD. This analysis was performed for two types of kidney stones of different materials. Since these stones are not isolated in a human body, the influence of the surrounding soft tissue on the XRD pattern is investigated and a correction for this soft tissue contribution is introduced.

The first epidemiology of urolithiasis in Northern Vietnam: Urinary stone composition, age, gender, season, and clinical features study

OBJECTIVES

The aim of this study is to analyze the compositions of urinary stones and investigate their distributions in different ages, genders, seasons, and clinical features of Northern Vietnamese patients.

METHODS

A total of 231 patients with urinary stones from Northern Vietnam were collected and analyzed composition from 1/2021-12/2022. For all patients, age, sex, stone location, stone side, urine pH, and hospitalized date (month) were collected.

RESULTS

Kidney stones are more frequently found in men than women with the male: female urinary stones ratio in this study being 1.96:1. The highest stone prevalence appeared between 60 and 69 years old. The most common stone composition was calcium oxalate, followed by calcium phosphate, uric acid, struvite, and cysteine. Mix stones of CaOx and CaP were more prevalent than pure stones. Males submitted more CaOx, CaP, and UA stones, whereas females were susceptible to infectious stones. Stones were more frequently found on the left side of the upper urinary tract (51.9%) than on the right side (27.3%) and lower urinary tract (7.8%). Cultural tendency leads to a smaller number of stones during the Lunar new year (February), and Ghost month (August).

Urine pH and Citrate as Predictors of Calcium Phosphate Stone Formation

Key Points

The occurrence of calcium phosphate stones has increased over the past five decades, and this is most notable in female stone formers. High urine pH and hypocitraturia are the most discriminatory urine parameters between calcium phosphate and calcium oxalate stone formers. High urine pH in calcium phosphate stone formers is independent of the effect of dietary alkali and acid.

Background

Urinary parameters, including urine pH and citrate, are recognized as critical in the pathophysiology of calcium-based stones. The factors contributing to variation in these parameters between calcium oxalate (CaOx) and calcium phosphate (CaP) stone formers (SFs) are, however, not well-understood. In this study, using readily available laboratory data, we explore these differences to delineate the odds of forming CaP versus CaOx stones.

Methods

In this single-center retrospective study, we compared serum and urinary parameters between adult CaP SFs, CaOx SFs, and non–stone formers.

Results

Urine pH was higher and urine citrate lower in CaP SFs compared with same-sex CaOx SFs and non–stone formers. In CaP SFs, higher urine pH and lower citrate were independent of markers of dietary acid intake and gastrointestinal alkali absorption, suggesting abnormal renal citrate handling and urinary alkali excretion. In a multivariable model, urine pH and urine citrate were most discriminatory between CaP SFs and CaOx SFs (receiver-operating characteristic area under the curve of 0.73 and 0.65, respectively). An increase in urine pH by 0.35, a decrease in urine citrate by 220 mg/d, a doubling of urine calcium, and female sex all independently doubled the risk of CaP stone formation compared with CaOx stones.

Conclusions

High urine pH and hypocitraturia are two clinical parameters that distinguish the urine phenotype of CaP SFs from CaOx SFs. Alkalinuria is due to intrinsic differences in the kidney independent of intestinal alkali absorption and is accentuated in the female sex.

Spectrum of Bacterial Pathogens from Urinary Infections Associated with Struvite and Metabolic Stones

OBJECTIVE

The purposes of this multi-center study were to evaluate the rate of infection stones and to evaluate the urine cultures of patients with infection stones.

MATERIALS

Charts of adulpatients with urinary stones were reviewed and data on stone analyses and urine cultures were collected.

RESULTS

In total, 1204 renal stone formers (RSFs) from 10 countries were included (776 males, 428 females). Fifty-six patients (4.6%) had struvite stones. The highest frequency of struvite stones was observed in India (23%) and Pakistan (18%). Lower rates were reported in Canada (2%), China (3%), Argentina (3%), Iraq (3%), Italy (3.5%) and Poland (3%), and intermediate rates in Egypt (5.5%) and Bulgaria (5.4%). Urine cultures were retrieved from 508 patients. Patients with struvite stones had a positive culture in 64.3% of the samples and patients with other stones, in 26.7%. In struvite stones, the most common isolates were Escherichia coli (27.7%) and Proteus spp. (27.7%), followed by Klebsiella spp. (16.7%); in other types of stone, it was Escherichia coli (47.6%), followed by Gram-positive bacteria (14.0%) Conclusions: The struvite stone composition was associated with a urinary infection, although an infection was not demonstrable with a conventional midstream urine culture in about 30%.

Application of Radiomics Model of CT Images in the Identification of Ureteral Calculus and Phlebolith

OBJECTIVE

To investigate the clinical application of the three-dimensional (3D) radiomics model of the CT image in the diagnosis and identification of ureteral calculus and phlebolith.

METHOD

Sixty-one cases of ureteral calculus and 61 cases of phlebolith were retrospectively investigated. The enrolled patients were randomly categorized into the training set (n = 86) and the testing set (n = 36) with a ratio of 7 : 3. The plain CT scan images of all samples were manually segmented by the ITK-SNAP software, followed by radiomics analysis through the Analysis Kit software. A total of 1316 texture features were extracted. Then, the maximum correlation minimum redundancy criterion and the least absolute shrinkage and selection operator algorithm were used for texture feature selection. The feature subset with the most predictability was selected to establish the 3D radiomics model. The performance of the model was evaluated by the receiver operating characteristic (ROC) curve, and the area under the ROC curve (AUC) was also calculated. Additionally, the decision curve was used to evaluate the clinical application of the model.

RESULTS

The 10 selected radiomics features were significantly related to the identification and diagnosis of ureteral calculus and phlebolith. The radiomics model showed good identification efficiency for ureteral calculus and phlebolith in the training set (AUC = 0.98; 95%CI: 0.96-1.00) and testing set (AUC = 0.98; 95%CI: 0.95-1.00). The decision curve thus demonstrated the clinical application of the radiomics model.

CONCLUSIONS

The 3D radiomics model based on plain CT scan images indicated good performance in the identification and prediction of ureteral calculus and phlebolith and was expected to provide an effective detection method for clinical diagnosis.

Stone composition of renal stone formers from different global regions

OBJECTIVE

To study urinary stone composition patterns in different populations around the world.

MATERIALS AND METHODS

Data were collected by reviewing charts of 1204 adult patients of 10 countries with renal or ureteral stones (> 18 years) in whom a stone analysis was done and available. Any method of stone analysis was accepted, but the methodology had to be registered.

RESULTS

In total, we observed 710 (59%) patients with calcium oxalate, 31 (1%) with calcium phosphate, 161 (13%) with mixed calcium oxalate/calcium phosphate, 15 (1%) with carbapatite, 110 (9%) with uric acid, 7 (< 1%) with urate (ammonium or sodium), 100 (9%) with mixed with uric acid/ calcium oxalate, 56 (5%) with struvite and 14 (1%) with cystine stones. Calciumcontaining stones were the most common in all countries ranging from 43 to 91%. Oxalate stones were more common than phosphate or mixed phosphate/oxalate stones in most countries except Egypt and India. The rate of uric acid containing stones ranged from 4 to 34%, being higher in Egypt, India, Pakistan, Iraq, Poland and Bulgaria. Struvite stones occurred in less than 5% in all countries except India (23%) and Pakistan (16%). Cystine stones occurred in 1% of cases.

CONCLUSIONS

The frequency of different types of urinary stones varies from country to country. Calcium-containing stones are prevalent in all countries. The frequency of uric acid containing stones seems to depend mainly on climatic factors, being higher in countries with desert or tropical climates. Dietary patterns can also lead to an increase in the frequency of uric acid containing stones in association with high obesity rates. Struvite stones are decreasing in most countries due to improved health conditions.

A 13 year hospital based study on the Trend of Urinary Stone Disease in Uttarakhand, India

Background

The present retrospective study on urinary stone disease in the Uttarakhand state was necessitated as no study has been done yet.

Methods

A 13 year retrospective study (from 2005 to 2018) was conducted on the urinary stones removed from the patients, admitted at Himalayan Institute of Medical Sciences, Dehradun. The incidence of the disease, site of stones in urinary tract upon diagnosis, composition of removed stones and occurrence of a possible co-relationship between the incidence of the urinary stone disease at different times, age, sex, religion of the patients was investigated.

Results

The frequency of occurrence of urinary stones in males was found to be almost three times more as compared to their female counterparts. The above trend was consistent over the entire period of the study. Interestingly, in the Muslim and Sikh population of the area, females were found to be less prone to the problem as compared to their Hindu counterparts. However, in all religious groups, 21-40 years old subjects were found to be most susceptible to the problem and approximately 90% of the urinary stones were recovered from the kidneys and primarily composed of calcium oxalate.

Conclusion

The co-relationship between the occurrence of urinary stones with age, sex of the patients, their religion & site of stones on diagnosis was found to be statistically significant.

Klotho gene polymorphism in renal stone formers from Northwestern India

Klotho gene is an important gene involved in calcium homeostasis, and polymorphisms of this gene may render the individual prone to renal stone formation. We evaluated G395A single nucleotide polymorphisms (SNPs) of Klotho gene at rs1207568 in renal stone patients of North India. This was a prospective study involving 150 patients of renal stone disease (aged 15-60 years) and 100 age- and sex-matched controls. The DNA was isolated and subjected to polymerase chain reaction (PCR) for identifying the G395A Klotho SNPs at rs1207568. Confronting two pair primers were used, and gel electrophoresis showing two bands at 175,252 bp was considered as GG genotype, three bands at 121,175 and 252 bp as GA and two bands at 121 and 252 bp as AA genotype. The association between genotype and cases was evaluated by using Chi-square test and logistic regression analysis. Cases and controls were well matched for age (40.65 vs 42.06, p = 0.063) and sex (p = 0.420). Significantly high proportion of patients with renal stones had GG genotype as compared to controls (odds ratio (OR) 2.37(1.39,4.03), p = 0.001). None of the participants (cases and controls) had homozygous recessive AA genotype. The risk of stone formation was significantly higher in the population carrying G allele {OR 1.94 (1.225-3.073), p 0.004}. Mean serum calcium was higher in stone formers with GG genotype as compared to those with GA genotype (9.16 mg/dl vs 8.91 mg/dl; p = 0.06). GG genotype of G396A Klotho gene SNPs is associated with renal stone formation. The G allele carrier is twice at risk of renal stone formation. The absence of AA genotype in north-western Indian population remains a curiosity.

Urinary Calculi: A Microbiological and Biochemical Analysis at a Tertiary Care Hospital in Eastern Nepal

Background

The occurrence of urinary tract infection in presence of urolithiasis is frequently noted; however, microbial agents of urolithiasis and their antimicrobial susceptibility patterns remain underinvestigated. This study aimed to identify the microorganisms isolated from urine and stone matrices to determine their antimicrobial susceptibility, to find the association between the pathogens of urine and stone matrices, and to perform the biochemical analysis of stones.

Methods

A total of 88 cases of urolithiasis admitted for elective stone removal at Department of surgery, B.P. Koirala Institute of Health Sciences (BPKIHS), were enrolled. Preoperative urine culture and postoperative stone culture were performed. Isolation, identification, and AST were done by the standard microbiological technique. Further qualitative biochemical analysis of stones was also attempted.

Result

Among 88 stone formers recruited, culture of urine, whole stone, and nidus yielded the growth of bacteria 44, 32, and 30, respectively. Bacteria isolated from urine culture correlated with those from stone matrices with a sensitivity of 90%, specificity of 79.69%, PPV of 63.64%, and NPV of 95.45%. Escherichia coli (46.7%) was the most common bacteria followed by Klebsiella pneumoniae (16.7%) and Proteus mirabilis (13.3%) from urine and stone cultures. Almost all the uropathogens isolated were susceptible to commonly used antibiotics. Calcium oxalate (84.1%) was common biochemical constituent found in stone formers followed by calcium oxalate + phosphate (8%).

Conclusions

The association of microorganism isolated from urine and nidus culture was significant that can predict the source of infective stone; however, in some cases, microorganisms and the antimicrobial susceptibility pattern from urine and nidus were different. This study emphasizes the use of appropriate antimicrobial agents to prevent the regrowth of residual stones and minimize the risk of infectious complications after surgical removal of stones.

The Urological Association of Asia clinical guideline for urinary stone disease

The Urological Association of Asia, consisting of 25 member associations and one affiliated member since its foundation in 1990, has planned to develop Asian guidelines for all urological fields. The field of stone diseases is the third of its guideline projects. Because of the different climates, and social, economic and ethnic environments, the clinical practice for urinary stone diseases widely varies among the Asian countries. The committee members of the Urological Association of Asia on the clinical guidelines for urinary stone disease carried out a surveillance study to better understand the diversity of the treatment strategy among different regions and subsequent systematic literature review through PubMed and MEDLINE database between 1966 and 2017. Levels of evidence and grades of recommendation for each management were decided according to the relevant strategy. Each clinical question and answer were thoroughly reviewed and discussed by all committee members and their colleagues, with suggestions from expert representatives of the American Urological Association and European Association of Urology. However, we focused on the pragmatic care of patients and our own evidence throughout Asia, which included recent surgical trends, such as miniaturized percutaneous nephrolithotomy and endoscopic combined intrarenal surgery. This guideline covers all fields of stone diseases, from etiology to recurrence prevention. Here, we present a short summary of the first version of the guideline - consisting 43 clinical questions - and overview its key practical issues.

Epidemiology of urolithiasis in Asia

In Asia, about 1%-19.1% of the population suffer from urolithiasis. However, due to variations in socio-economic status and geographic locations, the prevalence and incidence have changed in different countries or regions over the years. The research for risk factors of urinary tract stones is of predominant importance. In this review, we find the prevalence of urolithiasis is 5%-19.1% in West Asia, Southeast Asia, South Asia, as well as some developed countries (South Korea and Japan), whereas, it is only 1%-8% in most part of East Asia and North Asia. The recurrence rate ranges from 21% to 53% after 3-5 years. Calcium oxalate (75%-90%) is the most frequent component of calculi, followed by uric acid (5%-20%), calcium phosphate (6%-13%), struvite (2%-15%), apatite (1%) and cystine (0.5%-1%). The incidence of urolithiasis reaches its peak in population aged over 30 years. Males are more likely to suffer from urinary calculi. Because of different dietary habits or genetic background, differences of prevalence among races or nationalities also exist. Genetic mutation of specific locus may contribute to the formation of different kinds of calculi. Dietary habits (westernized dietary habits and less fluid intake), as well as climatic factors (hot temperature and many hours of exposure to sunshine) play a crucial role in the development of stones. Other diseases, especially metabolic syndrome, may also contribute to urinary tract stones.

Variation in Kidney Stone Composition Within the United States

INTRODUCTION AND OBJECTIVES

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Role of computed tomography morphodensitometry in predicting the outcome of shock wave lithotripsy

Objectives:

The objective of this study was to predict the outcome of shock wave lithotripsy (SWL) on the basis of computed tomography (CT) morphodensitometry for ureteral and renal stones. We also assessed the possibility that Hounsfield unit (HU) values and the location of the stones could be used to predict the outcome of SWL.

Material and methods:

A prospective study was performed to measure stone size, location, composition, surface area, surface volume, stone burden, the skin-to-stone distance and the HU for solitary renal and ureteral stones by non-contrast CT studies (NCCT) from August 2013 to September 2015. Success of SWL was defined as: (1) being stone-free or (2) residual stone fragments < 4 mm by radiography/NCCT.

Results:

Of the 100 assessed patients, 68 patients (68%) were stone-free, 12 (12%) had residual stone fragments < 4 mm (clinically insignificant residual fragments) and 20 (20%) had residual stone fragments ≥ 4 mm/ancillary procedures. Multivariate analysis revealed that stone location and mean HU were significant predictors of SWL success. Receiver operating characteristic curves defined cut-off values for predicting treatment outcome. Treatment success rates were significantly higher for stones < 800 HU than with stones > 800 HU ( p = 0.160).

Conclusion:

Evaluation of stone HU values and stone location prior to SWL can predict treatment outcome and aid in the development of treatment strategies.

Level of evidence

2 & 4

Phase composition and morphological characterization of human kidney stones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis

Pathological calcification in human urinary tract (kidney stones) is a common problem affecting an increasing number of people around the world. Analysis of such minerals or compounds is of fundamental importance for understanding their etiology and for the development of prophylactic measures. In the present study, structural characterization, phase quantification and morphological behaviour of thirty three (33) human kidney stones from eastern India have been carried out using IR spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). Quantitative phase composition of kidney stones has been analyzed following the Rietveld method. Based on the quantitative estimates of constituent phases, the calculi samples have been classified into oxalate (OX), uric acid (UA), phosphate (PH) and mixed (MX) groups. Rietveld analysis of PXRD patterns showed that twelve (36%) of the renal calculi were composed exclusively of whewellite (calcium oxalate monohydrate, COM). The remaining twenty one (64%) stones were mixture of phases with oxalate as the major constituent in fourteen (67%) of these stones. The average crystallite size of whewellite in oxalate stones, as determined from the PXRD analysis, varies between 93 (1) nm and 202 (3) nm, whereas the corresponding sizes for the uric acid and struvite crystallites in UA and PH stones are 79 (1)-155 (4) nm and 69 (1)-123(1) nm, respectively. The size of hydroxyapatite crystallites, 10 (1)-21 (1) nm, is smaller by about one order of magnitude compared to other minerals in the kidney stones. A statistical analysis using fifty (50) kidney stones (33 calculi from the present study and 17 calculi reported earlier from our laboratory) revealed that the oxalate group (whewellite, weddellite or mixture of whewellite and weddellite as the major constituent) is the most prevalent (82%) kidney stone type in eastern India.

Spectrum of urinary stone composition in Northwestern Rajasthan using Fourier transform infrared spectroscopy

Introduction:

The aim of this study was to evaluate the chemical composition of urinary stones and pattern of changes according to the patient's age in Northwestern Rajasthan using Fourier transform infrared (FTIR) spectroscopy.

Materials and Methods:

A prospective study of 1005 urolithiasis patients was carried out in two tertiary care centers from September 2012 to September 2016. Chemical composition of urinary stones was analyzed using FTIR spectroscopy, and a subgroup study based on the patient's age was done (8–12 years – Group A, 13–18 years – Group B, and >18 years – Group C).

Results:

Out of 1005 patients, 59 were in Group A, 104 in Group B, and 842 in Group C. Male predominance was found in all age groups. Mixed composition stones were much more common than pure one (74.83% vs. 25.17%). Overall, combination of calcium oxalate monohydrate with dihydrate was the most common composition (58.0%). Calcium oxalate was the predominant chemical composition in 91.54% of stones, followed by uric acid in 4.28%, struvite in 2.29%, calcium phosphate in 1.49%, and cystine in 0.4%. The proportion of calcium oxalate stone was increasing while that of struvite, uric acid, and cystine stone was decreasing with age. Most of the vesical calculi in pediatric age group (Group A; 8–12 years) patients were made up of combination of struvite, calcium phosphate, and uric acid. A total of 85.11% of staghorn calculi were of oxalates.

Conclusion:

In Northwestern Rajasthan, calcium oxalate is the most common composition of urinary stones in all age groups. Mixed stones are more common than pure ones. The incidence of calcium oxalate stone increases while that of struvite, uric acid, and cystine stone decreases with age.

Compositional analysis of various layers of upper urinary tract stones by infrared spectroscopy

The objective of the present study was to determine the composition of various layers of upper urinary stones and assess the mechanisms of stone nucleation and aggregation. A total of 40 integrated urinary tract stones with a diameter of >0.8 cm were removed from the patients. All of the stones were cut in half perpendicularly to the longitudinal axis. Samples were selected from nuclear, internal and external layers of each stone. Fourier transform infrared spectroscopy (FT-IR) was adopted for qualitative and quantitative analysis of all of the fragments and compositional differences among nuclear, internal and external layers of various types of stone were subsequently investigated. A total of 25 cases of calcium oxalate (CaOx) stones and 10 cases of calcium phosphate (CaP) stones were identified to be mixed stones, while 5 uric acid (UA) calculi were pure stones (purity, >95%). In addition, the contents of CaOx and carbapatite (CA.AP) crystals in various layers of the mixed stones were found to be variable. In CaOx stones, the content of CA.AP in nuclear layers was significantly higher than that of the outer layers (32.0 vs. 6.8%; P<0.05), while the content of CaOx was lower in the inner than in the outer layers (57.6 vs. 86.6%; P<0.05). In CaP stones, the content of CA.AP in the nuclear layers was higher than that in the outer layers (74.0 vs. 47.3%; P<0.05), while the content of CaOx was lower in the inner than in the outer layers (7.0 vs. 40.0%; P<0.05). The UA stones showed no significant differences in their composition among different layers. In conclusion, FT-IR analysis of various layers of human upper urinary tract stones revealed that CaOx and CaP stones showed differences in composition between their core and surface, while all of the UA calculi were pure stones. The composition showed a marked variation among different layers of the stones, indicating that metabolism has an important role in different phases of the evolution of stones. The present study provided novel insight into the pathogenesis of urinary tract stones and may contribute to their prevention and treatment.

Epidemiology, pathophysiology, and management of uric acid urolithiasis: A narrative review

An in-depth comprehension of the epidemiology as well as pathophysiology of uric acid urolithiasis is important for the identification, treatment, and prophylaxis of calculi in these patients. Persistently low urinary pH, hyperuricosuria, and low urinary volume are the most important factors in pathogenesis of uric acid urolithiasis. Other various causes of calculus formation comprises of chronic diarrhea, renal hyperuricosuria, insulin resistance, primary gout, extra purine in the diet, neoplastic syndromes, and congenital hyperuricemia. Non-contrast-enhanced computed tomography is the radiologic modality of choice for early assessment of patients with renal colic. Excluding situations where there is acute obstruction, rising blood chemistry, severe infection, or unresolved pain, the initial management ought to be medical dissolution by oral chemolysis since this method has proved to be effective in most of the cases.

Prevalence of renal uric acid stones in the adult

The aim of this study was to estimate uric acid renal stone prevalence rates of adults in different countries of the world. PubMed was searched for papers dealing with "urinary calculi and prevalence or composition" for the period from January 1996 to June 2016. Alternative searches were made to collect further information on specific topics. The prevalence rate of uric acid stones was computed by the general renal stone prevalence rate and the frequency of uric acid stones in each country. After the initial search, 2180 papers were extracted. Out of them, 79 papers were selected after the reading of the titles and of the abstracts. For ten countries, papers relating to both the renal stone prevalence in the general population and the frequency of uric stones were available. Additional search produced 13 papers that completed information on 11 more countries in 5 continents. Estimated prevalence rate of uric acid stones was >0.75% in Thailand, Pakistan, Saudi Arabia, Iran, South Africa (white population), United States and Australia; ranged 0.50-0.75% in Turkey, Israel, Italy, India (Southern), Spain, Taiwan, Germany, Brazil; and <0.50% in Tunisia, China, Korea, Japan, Caribe, South Africa (blacks), India (Northern). Climate and diet are major determinants of uric acid stone formation. A hot and dry climate increases fluid losses reducing urinary volume and urinary pH. A diet rich in meat protein causes low urinary pH and increased uric acid excretion. On the other hand, uric acid stone formation is frequently associated with obesity, metabolic syndrome and diabetes type 2 that are linked to dietary energy excess mainly from carbohydrate and saturated fat and also present with low urine pH values. An epidemic of uric acid stone formation could be if current nutritional trends will be maintained both in developed countries and in developing countries and the areas of greater climatic risk for the formation of uric acid stones will enlarge as result of the "global warming".

An Increase Incidence in Uric Acid Nephrolithiasis: Changing Patterns

INTRODUCTION

Nephrolithiasis is a complex disease affecting all age groups globally. As the causative factors for nephrolithiasis rises significantly, its incidence, prevalence and recurrence continues to baffle clinicians and patients.

AIM

To study the prevalence of different types of renal stones extracted by Percutaneous Nephrolithotomy (PCNL) and open surgical procedures.

MATERIALS AND METHODS

Renal stones from 50 patients were retrieved by Percutaneous Nephrolithotomy (PCNL), Ureterorenoscopy (URS) and open surgical techniques for qualitative tests for detection of calcium, oxalate, uric acid, phosphate, ammonium ion, carbonate, cystine and xanthine.

RESULTS

Three patients had stone removed by open surgery and rest had undergone PCNL. Nine of the stones were pure of calcium oxalate, 9 were of pure uric acid and 32 were mixed stones. Forty one stones had calcium. Among the mixed stones, oxalate was present in 25 samples (39 of total), uric acid was seen in 17 (25 of total stones), phosphate was present in 23 (23 of total) and carbonate was present in 4 stones (4 of total). Only 1 patient had triple phosphate stone. 12 were of staghorn appearance of which 6 were of struvite type, 6 were pure uric acid and remaining were mixed oxalate-phosphate stones.

CONCLUSION

Our study, though in a small number of hospital based patients, found much higher prevalence of uric acid stones and mixed stones than reported by previous hospital based studies in north India (oxalate stones~90%, uric acid~1% and mixed stones~3%). Biochemical analysis of renal stones is warranted in all cases.

Dual energy can accurately differentiate uric acid-containing urinary calculi from calcium stones

PURPOSE

To retrospectively evaluate the accuracy of dual-energy CT (DECT) in the detection of the chemical composition of urinary calculi in correlation with infrared spectroscopic stone analysis.

METHODS

We reviewed the CT scans of 255 patients who underwent DECT due to a clinical suspicion of urolithiasis. Out of this group, we included 64 patients with clinically symptomatic urolithiasis requiring stone removal. After surgical removal of the stone by ureterorenoscopy, chemical composition was analyzed with infrared spectroscopy. We correlated DECT stone characterization results with chemical stone composition based on dual-energy indices (DEI). A total of 213 renal and ureteral stones could be removed and chemically analyzed.

RESULTS

A total of 213 calculi were evaluated. Thirty eight out of sixty four (59 %) patients had >1 stone. DECT was used to differentiate stones by using DEI. Stones harboring calcium (CA) were color-coded in blue, while stones containing uric acid (UA) were colored red. Median DEI in UA-containing stones were 0.001. Non-UA-containing stones had a DEI between 0.073 for pure CA stones and 0.077 containing CA and other substances (p = 0.001; p = 0.03, respectively). Sensitivity of DECT was 98.4 % for differentiation of UA from non-UA-containing calculi. Specificity was 98.1 %. Mean effective radiation dose of DECT was 4.18 mSv (0.44-14.27 mSv), thus comparable to conventional CT scans of the abdomen. Conventional measurement of Hounsfield units did not correlate with stone composition.

CONCLUSION

DECT with image post-processing reliably discriminates UA-containing calculi from all other stones, but the study offered limitations. Discrimination within the non-UA stones cannot be reliably achieved but is clinically insignificant.

HPLC method for urinary theobromine determination: Effect of consumption of cocoa products on theobromine urinary excretion in children

OBJECTIVE

To validate a simple method of urinary theobromine determination, to assess urinary theobromine levels in 80 healthy children and to relate these levels to consumption of cocoa products.

DESIGN AND METHODS

Urine samples were diluted, directly injected into an HPLC system, separated by gradient elution on a C18 column, and detected by UV spectrometry. The method was validated for linearity, limits of detection and quantification, imprecision, accuracy, recovery and interferences. The proposed method was used to assess 12-h day and 12-h night urinary theobromine excretion by 80 healthy children, divided into four groups based on consumption of cocoa products. In addition, urinary excretion of magnesium and oxalate, also present in cocoa, was measured in these four groups.

RESULTS

The method was linear to a theobromine concentration of 278μmol/L (50mg/L). LOD and LOQ for urine samples, diluted 1:5 (vol/vol) with water, were 1.1 and 3.6μmol/L respectively. Within-run and between-run imprecisions (CV) were each <2%. Average recovery was 99%, and analysis of a certified reference sample showed an error <2.5%. Theobromine excretion levels were significantly higher in healthy children with higher consumption of cocoa products (p<0.001), but oxalate (p=0.098) and magnesium (p=0.068) excretion levels did not differ significantly.

CONCLUSION

This validated method resulted in urinary theobromine determination with 100% recovery, without sample pretreatment. Urinary theobromine levels in healthy children were directly related to their consumption of cocoa products.

In vivo characterization of urinary calculi on dual-energy CT: going a step ahead with sub-differentiation of calcium stones

BACKGROUND

The role of dual-energy computed tomography (DECT) in characterization of urinary calculi is evolving and literature regarding differentiation of calcium calculi is sparse and confounding.

PURPOSE

To evaluate the capability of DECT in assessing the urinary calculi composition in vivo, especially in differentiating various types of calcium calculi.

MATERIAL AND METHODS

One hundred and twenty patients underwent DECT for characterization of urinary calculi. Seventy patients with 114 calculi, including 93 calcium stones, were retrospectively analyzed. DE ratios and attenuation differences were compared using ANOVA and receiver-operating-characteristic (ROC) analysis was done to predict cut-off values, in particular for detecting calcium-oxalate-monohydrate (COM) stones.

RESULTS

DE ratio ≤1.14 accurately detected uric acid calculi, ≥1.29 was definitive for calcium and intermediate values were characteristic of cystine stones. DE ratios were significantly different between group 1 (COM [n = 32]; mean 1.376 ± 0.041), group 2 ([calcium oxalate dihydrate (COD) + COM] [n = 51]; 1.416 ± 0.048), and group 3 ([carbonate apatite (CaP) + COD + COM] [n = 10]; 1.468 ± 0.038) (group 1 vs. 2, P = 0.001; 1 vs. 3, P = 0.000; 2 vs. 3, P = 0.004). More importantly, pure COM calculi (group 1) had significantly lower DE ratio compared with mixed calcium calculi (groups 2 and 3) (P = 0.000). Attenuation differences (between low and high kV images) could not distinguish between COM and mixed calculi. ROC analysis for detection of COM calculi yielded AUC of 0.770 with cut-off DE ratio 1.385 (sensitivity 65.6%, specificity 82%) and value <1.335 was seen only with COM calculi (100% specificity).

CONCLUSION

DECT can be employed for in vivo differentiation of various types of calculi and for detection of relatively lithotripsy-resistant COM calculi.

FT-IR spectroscopic, thermal analysis of human urinary stones and their characterization

In the present study, FT-IR, XRD, TGA-DTA spectral methods have been used to investigate the chemical compositions of urinary calculi. Multi-components of urinary calculi such as calcium oxalate, hydroxyl apatite, struvite and uric acid have been studied. The chemical compounds are identified by FT-IR spectroscopic technique. The mineral identification was confirmed by powder X-ray diffraction patterns as compared with JCPDS reported values. Thermal analysis techniques are considered the best techniques for the characterization and detection of endothermic and exothermic behaviors of the urinary stones. The percentages of each hydrate (COM and COD) are present together, in the presences of MAPH or UA. Finally, the present study suggests that the Urolithiasis is significant health problem in children, and is very common in some parts of the world, especially in India. So that present study is so useful and helpful to the scientific community for identification of latest human health problems and their remedies using spectroscopic techniques.

Theobromine inhibits uric acid crystallization. A potential application in the treatment of uric acid nephrolithiasis

PURPOSE

To assess the capacity of methylxanthines (caffeine, theophylline, theobromine and paraxanthine) to inhibit uric acid crystallization, and to evaluate their potential application in the treatment of uric acid nephrolithiasis.

MATERIALS AND METHODS

The ability of methylxathines to inhibit uric acid nucleation was assayed turbidimetrically. Crystal morphology and its modification due to the effect of theobromine were evaluated by scanning electron microscopy (SEM). The ability of theobromine to inhibit uric acid crystal growth on calculi fragments resulting from extracorporeal shock wave lithotripsy (ESWL) was evaluated using a flow system.

RESULTS

The turbidimetric assay showed that among the studied methylxanthines, theobromine could markedly inhibit uric acid nucleation. SEM images showed that the presence of theobromine resulted in thinner uric acid crystals. Furthermore, in a flow system theobromine blocked the regrowth of post-ESWL uric acid calculi fragments.

CONCLUSIONS

Theobromine, a natural dimethylxanthine present in high amounts in cocoa, acts as an inhibitor of nucleation and crystal growth of uric acid. Therefore, theobromine may be clinically useful in the treatment of uric acid nephrolithiasis.

Analysis of urinary stone composition in Eastern India by X-ray diffraction crystallography

Background:

Stones in the urinary system are common in our country. This study was done to assess the composition of the urinary stones in eastern part of India.

Materials and Methods:

A prospective study was done over a period of thirty months. A total of 90 stones were analyzed in this time period by using X-ray diffraction crystallography.

Results:

Of the 90 stones analyzed, 77 were renal stones, 12 were ureteric stones and one was a bladder stone. Six stones (all renal) did not have properties to be represented by X-ray diffraction crystallography. The overall prevalence of the oxalate containing stones was 85.7% with calcium oxalate monohydrate (COM) being the major constituent. Calcium oxalate dihydrate (COD) was the next most common constituent. Struvite stones constituted 9.5% of the stones analyzed. Pure calcium phosphate stones were found in 4.7% of the cases.

Conclusion:

Our study reveals that the stone composition in the eastern part of India is different from that in other parts of the country. We have a comparatively lower prevalence of oxalate stones while a higher prevalence of phosphate and struvite stones.

Variation in urinary stone composition between adult Uyghur and Han patients with urolithiasis in Xinjiang, China

OBJECTIVE

To analyze variations in urinary stone composition between Uyghur and Han patients with urolithiasis in Xinjiang, China, and to explore the possible factors associated with urinary stone composition in Uyghur and Han patients.

MATERIALS AND METHODS

We analyzed the components of urinary stones in 317 adults (152 Uyghur and 165 Han) with urolithiasis admitted to our hospital from March 2009 to June 2011. Urinary stones were collected by endoscopic or open surgical procedures and analyzed by infrared spectroscopy. Also analyzed were clinical data, including patient's age, sex, geographic distribution, blood tests, and urine tests. Logistic regression was performed to analyze the association between stone components and the clinical characteristics of the patients.

RESULTS

There were significant differences between Uyghur and Han patients in age, geographic distribution, serum concentrations of uric acid, potassium, and phosphorus, urine magnesium concentrations, 24-hour volumes of urine, and in stone components of calcium oxalate monohydrate, calcium oxalate dihydrate plus carbapatite, and uric acid. Differences in sex, family history, complications, sites of calculi, or other blood and urine test results were not significant. Logistic regression analysis revealed that geographic location, ethnicity, blood potassium concentration, and urine volume were significantly correlated with the calcium oxalate dihydrate plus carbapatite component of urinary stones.

CONCLUSION

Urinary stone composition differs between Uyghur and Han patients with urolithiasis, possibly as a result of geographic distribution.

Randall's plaque as the origin of calcium oxalate kidney stones

Eight decades ago, Alexander Randall identified calcium phosphate deposits at the tip of renal papillae as the origin of renal calculi. The awareness that these "Randall's plaque" promote renal stone formation has been amplified during the past years by the development of endoscopic procedures allowing the in situ visualization of these plaques. Recent studies based upon kidney biopsies evidenced that apatite deposits at the origin of these plaque originate from the basement membranes of thin loops of Henle and then spread in the surrounding interstitium. In addition, scanning electron microscopy examination of calcium oxalate stones developed on Randall's plaque evidenced that plaque may also be made of tubules obstructed by calcium phosphate plugs. Hypercalciuria has been associated to Randall's plaque formation. However, several additional mechanisms may be involved resulting in increased tissular calcium phosphate supersaturation and the role of macromolecules in plaque formation remains elusive. At last, apatite crystals are the main mineral phase identified in plaques, but other calcium phosphates and various chemical species such as purines have been evidenced, revealing thereby that several mechanisms may be responsible for plaque formation.

High incidence of urinary stones in Uyghur children may be related to local environmental factors

OBJECTIVE

To analyze the causes of urolithiasis in Uyghur children from Xinjiang.

PATIENTS AND METHODS

We retrospectively evaluated the clinical features and characteristics of urinary stone composition of 220 Uyghur pediatric patients with urolithiasis between March 2009 and June 2011. The data were compared with that of 100 Uyghur children without urolithiasis who visited the Child Care Clinic for regular health check-ups. The stones were collected by endoscopy or open surgery, and analyzed using infrared spectroscopy.

RESULTS

The mean age of the 220 Uyghur children was 7.48 ± 4.73 years (range, 0.8-17.0 years). The overall sex ratio (male:female) was 2.23:1. The predominant pure stone was ammonium urate (58.9%), whereas the predominant mixed stone was calcium oxalate mixture (91.1%). Uric acid stones comprised 54% of all stones. Urinary tract infections were observed in 42.3% and 4.0% of the patient and control groups, respectively. The mean urinary pH values were 5.77 ± 0.67 and 6.42 ± 0.67, respectively (p < 0.001). pH values were <5.5 in 52.7% and 6% of the patient and control groups, respectively. On 24-h urine analysis, we found metabolic disturbances in these patients: hypercalciuria in 6.8% cases, hyperphosphaturia in 16.8% cases, hyperuricosuria in 21.4% cases, and hypomagnesiuria in 34.1% cases.

CONCLUSIONS

Urolithiasis in Uyghur children may be primarily related to local environmental factors.

Growth and Characterization of Agar Gel Grown Brushite Crystals

Brushite [CaHPO4·2H2O] or calcium hydrogen phosphate dihydrate (CHPD) also known as urinary crystal is a stable form of calcium phosphate. The brushite crystals were grown by single and double diffusion techniques in agar-agar gel at room temperature. Effects of different growth parameters were discussed in single diffusion and double diffusion techniques. Good quality star, needle, platy, rectangular, and prismatic shaped crystals in single diffusion and nuclei with dendritic growth were obtained in double diffusion. These grown nuclei were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). SEM has shown the different morphologies of crystals; FTIR has confirmed the presence of functional groups; crystalline nature was supported by XRD, whereas the TGA indicates total 24.68% loss in weight and formation of stable calcium pyrophosphate (Ca2P2O7) at 500°C.

Assessment of mineral intake by kidney stone patients of Kangra District, Himachal Pradesh with respect to their gender, age and income

OBJECTIVES

To assess the family history of stones and association of mineral intake with gender, age and income of kidney stone patients.

METHODS

A total of 130 kidney stone patients were selected randomly from Kangra district of Himachal Pradesh and family history of stones and mineral intake was assessed.

RESULTS

Out of selected patients, majority (80.77 %) were first time stone sufferers. There was significant (at 1 % level) association between family history of kidney stone patients with respect to gender of patients. Further study revealed that the intake of sodium, calcium, magnesium and phosphorous was higher than recommended dietary allowances (RDA). Among male patients, the intake of sodium, calcium and magnesium was higher for age group III (above 45 y) and intake of potassium and phosphorous was higher for age group I. In female kidney stone patients, intake of sodium, calcium and phosphorous was high for age group II, intake of potassium was high in case of age group I and intake of magnesium was high for age group III. Regression studies revealed that there was significantly higher intake of calcium and phosphorous by male kidney stone patients than female kidney stone patients. With the increase in age, the intake of calcium and phosphorous decreased.

CONCLUSIONS

Assessment of mineral intake is necessary to enable the health care providers, to give advice and suggestions to the patients to carry out preventive measures in reducing the risk of prevalence of kidney stones in this area and further advice to the suffering patients to prevent the recurrence of stone formation.

Current role of microperc in the management of small renal calculi

'Microperc' is a recently described technique in which percutaneous renal access and lithotripsy are performed in a single step using a 16 G micropuncture needle. 'Mini-microperc' is a further technical modification in which an 8 Fr sheath is used to allow insertion of ultrasonic or pneumatic lithoclast probe with suction. The available evidence indicates that microperc is safe and efficient in the management of small renal calculi in adult and pediatric population. It can also be used for renal calculi in ectopic kidneys and bladder calculi. The high stone clearance rate and lower complication rate associated with microperc make it a viable alternative to retrograde intrarenal surgery.

Risk factors for urolithiasis in gastrostomy tube fed children: a case-control study

BACKGROUND AND OBJECTIVE

Pediatric patients who are fed primarily via gastrostomy tube (G-tube) may be at increased risk for urolithiasis, but no studies have specifically examined risk factors for stones in this population. We aimed to determine clinical differences between G-tube fed (GTF) patients with and without stones, in hopes of identifying modifiable factors associated with increased risk of urolithiasis.

METHODS

We conducted a retrospective case-control study, matching GTF patients with urolithiasis (cases) to GTF children without urolithiasis (controls) based on age (±1 year) and gender. Bivariate comparisons and matched logistic regression modeling were used to determine the unadjusted and adjusted associations between relevant clinical factors and urolithiasis.

RESULTS

Forty-one cases and 80 matched controls (mean age 12.0 ± 6.5 years) were included. On bivariate analysis, factors associated with stone formation included: white race, urinary tract infection (UTI), topiramate administration, vitamin D use, malabsorption, dehydration, 2-year duration with G-tube, and whether goal free water intake was documented in the patient chart. On regression analysis, the following factors remained significant: topiramate administration (odds ratio [OR]: 6.58 [95% confidence interval (CI): 1.76-24.59]), UTI (OR: 7.70 [95% CI: 1.59-37.17]), and <2 years with a G-tube (OR: 8.78 [95% CI: 1.27-52.50]).

CONCLUSIONS

Our findings provide a preliminary risk profile for the development of urolithiasis in GTF children. Important associations identified include UTI, topiramate administration, and shorter G-tube duration, which may reflect subclinical chronic dehydration. Of these, topiramate use represents the most promising target for risk reduction.

Crystallite size--is it a new predictor for renal stone burden?

OBJECTIVE

To evaluate the importance of stone composition and crystallite size in the formation of ultimate stone burden. Crystallite is the smallest building block, which is unique in size and architecture for each type of stone component. Currently, the knowledge about the clinical importance of crystallite size is very limited.

METHODS

The results of quantitative X-ray diffraction phase analysis performed on 286 kidney stones extracted during endourological surgery or expelled spontaneously were retrospectively analyzed. Stone composition and crystallite size were determined and were compared to the burden occupying the pelvicalyceal system.

RESULTS

A total of 286 renal stones were analyzed. Stones were low burden and high burden in 242 and 44 of cases, respectively. We observed statistically significant association of phosphates and urates with high-burden stones in contrast to oxalates, which formed mainly low-burden stones. Crystallite sizes were available for 179 stones. Large-sized crystallites of calcium oxalate monohydrate and hydroxyl apatite formed low-burden stones, whereas small-sized crystallites formed staghorn stones. Struvite and urates had a uniform average size of crystallites.

CONCLUSION

Oxalate stones have statistically significant association with smaller stones, whereas high-burden calculi are significantly associated with urates and phosphates, especially the struvite type. The smaller the crystallite size is to start with, the larger will be the ultimate stone burden. This rule is followed by calcium oxalate monohydrate and Apatite minerals.

Preventive fluid and dietary therapy for urolithiasis: An appraisal of strength, controversies and lacunae of current literature

Regulation of fluid and dietary intake habits is essential in comprehensive preventive management of urolithiasis. However, despite large body of epidemiological database, there is dearth of good quality prospective interventional studies in this regard. Often there is conflict in pathophysiological basis and actual clinical outcome. We describe conflicts, controversies and lacunae in current literature in fluid and dietary modifications in prevention of urolithiasis. Adequate fluid intake is the most important conservative strategy in urolithiasis-prevention; its positive effects are seen even at low volumes. Of the citrus, orange provides the most favorable pH changes in the urine, equivalent to therapeutic alkaline citrates. Despite being richest source of citrate, lemon does not increase pH significant due to its acidic nature. Fructose, animal proteins and fats are implicated in contributing to obesity, which is an established risk factor for urolithiasis. Fructose and proteins also contribute to lithogenecity of urine directly. Sodium restriction is commonly advised since natriuresis is associated with calciuresis. Calcium restriction is not advisable for urolithiasis prevention. Adequate calcium intake is beneficial if taken with food since it reduces absorption of dietary oxalate. Increasing dietary fiber does not protect against urolithiasis. Evidence for pyridoxine and magnesium is not robust. There is no prospective interventional study evaluating effect of many dietary elements, including citrus juices, carbohydrate, fat, dietary fiber, sodium, etc. Due to lack of good-quality prospective interventional trials it is essential to test the findings of pathophysiological understanding and epidemiological evidence. Role of probiotics and phytoceuticals needs special attention for future research.

Changing composition of staghorn calculi

PURPOSE

The 2005 American Urological Association Guideline on the Management of Staghorn Calculi suggests that metabolic stones are uncommon in the composition of staghorn calculi. We determined the incidence and treatment outcomes of metabolic stones in patients with complete staghorn calculi compared to infection stones in those undergoing percutaneous nephrolithotomy.

MATERIALS AND METHODS

We retrospectively analyzed all patients who underwent percutaneous nephrolithotomy for complete staghorn calculi between April 2005 and April 2010. Stone analysis was reviewed to classify stone type as infectious or metabolic. Perioperative characteristics and patient outcomes were compared in relation to stone composition.

RESULTS

Of 52 kidneys (48 patients) with complete staghorn calculi 29 (56%) were metabolic and 23 (44%) were infection stones. Stone compositions in the metabolic group were calcium phosphate (55%), uric acid (21%), calcium oxalate (14%) and cystine (10%). Patients with metabolic stones were more likely male (55% vs 17%, p = 0.005) and more likely to have a negative preoperative urinary culture (62% vs 35%, p = 0.05). Patients with metabolic stones had a lower complication rate (p = 0.02), while those with infection stones tended to require additional access and secondary treatment, and to have higher recurrence rates. Multiple urinary metabolic abnormalities were noted in all 13 (48%) patients with metabolic stones who completed evaluation.

CONCLUSIONS

In a contemporary cohort of patients, metabolic stones comprised a large proportion of complete staghorn calculi. In our series calcium phosphate was the most common stone composition noted. Metabolic stones should be considered during the evaluation of staghorn calculi, and our results underscore the importance of stone analysis and subsequent metabolic evaluation in these patients.

Uric Acid Nephrolithiasis: A Systemic Metabolic Disorder

Uric acid nephrolithiasis is characteristically a manifestation of a systemic metabolic disorder. It has a prevalence of about 10% among all stone formers, the third most common type of kidney stone in the industrialized world. Uric acid stones form primarily due to an unduly acid urine; less deciding factors are hyperuricosuria and a low urine volume. The vast majority of uric acid stone formers have the metabolic syndrome, and not infrequently, clinical gout is present as well. A universal finding is a low baseline urine pH plus insufficient production of urinary ammonium buffer. Persons with gastrointestinal disorders, in particular chronic diarrhea or ostomies, and patients with malignancies with a large tumor mass and high cell turnover comprise a less common but nevertheless important subset. Pure uric acid stones are radiolucent but well visualized on renal ultrasound. A 24 h urine collection for stone risk analysis provides essential insight into the pathophysiology of stone formation and may guide therapy. Management includes a liberal fluid intake and dietary modification. Potassium citrate to alkalinize the urine to a goal pH between 6 and 6.5 is essential, as undissociated uric acid deprotonates into its much more soluble urate form.

Infrared spectroscopic analysis of 5,248 urinary stones from Chinese patients presenting with the first stone episode

A series of 5,248 urinary stones was analyzed by Fourier transform infrared spectroscopy between 1999 and 2008. This study evaluated the percentage of each stone type and the association with sex and age in Chinese stone formers presenting with the first stone episode. The overall sex ratio (male:female) was 2.34:1. Results showed that the preponderant type of stone was calcium oxalate, followed by carbapatite, anhydrous uric acid, struvite and cystine. Struvite stones in this study accounted for a relatively low rate compared to that reported by others. Of 5,248 stones, only 38.1% had one component, 42.5% consisted of two components, and 20.4% consisted of three components. Our results also showed the higher percentage of carbapatite stones in females than in males and the increment of anhydrous uric acid stones with age. In addition, the percentage of calcium oxalate stones decreased with increase in the percentage of carbapatite stones over the period.

Assessment of stone composition in the management of urinary stones

Several explanations have been suggested to account for the failure of extracorporeal shockwave lithotripsy (ESWL) treatment in patients with urinary stones, including large stone volume, unfavorable stone location or composition and the type of lithotriptor used. Unfavorable stone composition is considered a major cause of failure of ESWL treatment, and consequently knowledge of the stone composition before treatment is initiated is desirable. Plain abdominal radiographs cannot accurately determine either stone composition or fragility, and although the CT attenuation value in Hounsfield units (HU) (that is, normalized to the attenuation characteristics of water) is useful, this parameter has limited value as a predictor of stone composition or the response to ESWL treatment. By contrast, stone morphology as visualized by CT correlates well with both fragility and susceptibility to fragmentation by ESWL. For patients prone to recurrent calculi, analyses of stone composition are especially important, as they may reveal an underlying metabolic abnormality. The development of advanced imaging technologies that can predict stone fragility is essential, as they could provide extra information for physicians, enabling them to select the most appropriate treatment option for patients with urinary stones.

Nutritional aspect of nephrolithiasis

Nephrolithiasis is associated with a variety of abnormalities in urinary composition. These abnormal urinary risk factors are due to dietary indiscretions, physiological-metabolic disturbances or both. Stone disease is morbid and costly, and the recurrence rates may be as high as 30-50% after 5 years. Efforts to prevent stone formation are, therefore, essential. Dietary factors play an important role in kidney stone formation. Tailored dietary recommendations based on metabolic evaluation should be offered to patients for the prevention of recurrence of stone formation. Dietary intervention and subsequent evaluations of therapeutic efficacy should be based on results from multiple 24-h urine collections. Urine flow of >1 ml/kg/h almost eliminates the risk of supersaturation for calcium oxalate, calcium phosphate and uric acid, thus protecting from the formation of corresponding kidney stones. In patients with cystenuria, the required urine flow may even be higher and, in cases such as primary xanthinuria, high fluid intake is required. Milk intake in these patients should be within the RDA of calcium and protein. In children, recommendation of a high fluid intake has only limited success. Nevertheless, each patient should be advised about adequate fluid intake to increase urine volume in accordance with body size. Although children with hypocitraturia may benefit from therapeutic agents that raise the urine citrate concentration, all children bearing residual fragments should be counseled on adequate fluid intake along with potassium citrate treatment to prevent stone regrowth or formation.