Trends in renal calculus composition and 24-hour urine analyses in patients with neurologically derived musculoskeletal deficiencies

ABSTRACT Purpose: To better characterize metabolic stone risk in patients with neurologically derived musculoskeletal deficiencies (NDMD) by determining how patient characteristics relate to renal calculus composition and 24-hour urine parameters. Materials and Methods: We performed a retrospective cohort study of adult patients with neurologically derived musculoskeletal deficiencies presenting to our multidisciplinary Kidney Stone Clinic. Patients with a diagnosis of NDMD, at least one 24-hour urine collection, and one chemical stone analysis were included in the analysis. Calculi were classified as primarily metabolic or elevated pH. We assessed in clinical factors, demographics, and urine metabolites for differences between patients who formed primarily metabolic or elevated pH stones. Results: Over a 16-year period, 100 patients with NDMD and nephrolithiasis were identified and 41 met inclusion criteria. Thirty percent (12 / 41) of patients had purely metabolic calculi. Patients with metabolic calculi were significantly more likely to be obese (median body mass index 30.3kg / m2 versus 25.9kg / m2), void spontaneously (75% vs. 6.9%), and have low urine volumes (100% vs. 69%). Patients who formed elevated pH stones were more likely to have positive preoperative urine cultures with urease splitting organisms (58.6% vs. 16.7%) and be hyperoxaluric and hypocitraturic on 24-hour urine analysis (37mg / day and 265mg / day versus 29mg / day and 523mg / day). Conclusions: Among patients with NDMD, metabolic factors may play a more significant role in renal calculus formation than previously believed. There is still a high incidence of carbonate apatite calculi, which could be attributed to bacteriuria. However, obesity, low urine volumes, hypocitraturia, and hyperoxaluria suggest an underrecognized metabolic contribution to stone formation in this population.

Reporte de un caso de Cistinuria: Uso de herramientas de diagnóstico a nivel nacional / Report of a case of cystinuria: Use of diagnostic tools at national level

La cistinuria es una enfermedad genética que se engloba dentro de alteraciones congénitas del transporte de aminoácidos con formación de cálculos en las vías urinarias, si bien es poco frecuente se caracteriza por su elevada recurrencia. En este trabajo presentamos el caso de una paciente de 34 años, con antecedentes de haber perdido un riñón por episodios anteriores de litiasis y con múltiples recidivas que es diagnosticada mediante la detección de cistina por espectroscopía infrarroja como componente único de 96 fragmentos de cálculos removidos mediante nefrolitotomía percutánea. La paciente fue evaluada laboratorialmente mediante el perfil metabólico y la cristaluria. Las indicaciones de tratamiento específicas incluyeron la administración de agentes alcalinizantes, régimen nutricional, y entrenamiento para control de pH urinario. Es importante señalar la agresividad de la litiasis de cistina con las consecuencias que puede tener la calidad de vida del paciente, y por tanto la importancia de contar con capacidades instaladas a nivel país para el diagnóstico y seguimiento de litiasis genéticas como la causada por la cistinuria(AU)

Cystinuria is a genetic disease that is included among congenital defects of renal amino acids transport that causes urinary stone formation. Although it is rare, it is characterized by its high recurrence. We present the case of a 34-year-old patient that lost one of her kidney because of recurrent episodes of lithiasis, and that was diagnosed by the detection of cystine with infrared spectroscopy as the sole component of 96 stone fragments removed by percutaneous nephrolithotomy. The patient was evaluated by metabolic profile and crystalluria. The specific treatment indications included the administration of alkalinizing agents, nutritional regimen, and training for personal measurement of urinary pH. This case highlights the aggressiveness of cystine stones with the consequences that may have on the quality of the patient life, and therefore the importance of having installed proper diagnostic capacities at national level to detect and monitor treatment efficacy in genetic lithiasis such as cystinuria(AU)

Influence of nutritional status, laboratory parameters and dietary patterns upon urinary acid excretion in calcium stone formers / Influência do estado nutricional e dos parâmetros laboratoriais e dietéticos sobre a excreção urinária ácida em pacientes portadores de litíase cálcica

ABSTRACT Introduction: Obesity and Metabolic Syndrome (MS) are associated with low urinary pH and represent risk factors for nephrolithiasis, especially composed by uric acid. Acidogenic diets may also contribute to a reduction of urinary pH. Propensity for calcium oxalate precipitation has been shown to be higher with increasing features of the MS. Objective: A retrospective evaluation of anthropometric and body composition parameters, MS criteria and the dietary patterns of overweight and obese calcium stone formers and their impact upon urinary pH and other lithogenic parameters was performed. Methods: Data regarding anthropometry, body composition, serum and urinary parameters and 3-days dietary records were obtained from medical records of 102(34M/68F) calcium stone formers. Results: A negative correlation was found between urinary pH, waist circumference and serum uric acid levels (males). The endogenous production of organic acids (OA) was positively correlated with triglycerides levels and number of features of MS (males), and with glucose, uric acid and triglycerides serum levels, and number of features of MS (females). No significant correlations were detected between Net Acid Excretion (NAE) or Potential Renal Acid Load of the diet with any of the assessed parameters. A multivariate analysis showed a negative association between OA and urinary pH. Conclusion: The endogenous production of OA and not an acidogenic diet were found to be independently predictive factors for lower urinary pH levels in calcium stone formers. Hypercalciuric and/or hyperuricosuric patients presented higher OA levels and lower levels of urinary pH.

RESUMO Introdução: A obesidade e a Síndrome Metabólica (SM) se associam a pH urinário ácido e representam fatores de risco para litíase renal, especialmente a úrica. Dietas acidogênicas também podem contribuir para a redução do pH urinário. Já foi demonstrado maior risco de precipitação de oxalato de cálcio em proporção aos critérios de SM. Objetivo: Avaliar retrospectivamente o impacto de parâmetros antropométricos, composição corporal, critérios de SM e padrão alimentar sobre o pH urinário e outros parâmetros litogênicos em pacientes com sobrepeso e obesos com litíase cálcica. Métodos: Foram coletados dados de antropometria, composição corporal, exames séricos e urinários, e registros alimentares (3 dias) de 102 (34M/68F) pacientes com litíase cálcica. Resultados: O pH urinário se correlacionou negativamente com a circunferência da cintura e ácido úrico sérico (homens). A produção endógena de ácidos orgânicos (AO) se correlacionou positivamente com os triglicérides séricos e o número de critérios de SM (homens), e com glicemia, ácido úrico, triglicérides e número de critérios para SM (mulheres). Não se observaram correlações significantes entre a excreção renal líquida de ácidos (NAE) e o potencial de carga ácida renal (PRAL) da dieta com nenhum dos parâmetros avaliados. Na análise de regressão multivariada, os AO apresentaram associação negativa significante com o pH urinário. Conclusão: A produção endógena de AO, e não um padrão de dieta acidogênica, foi o fator determinante independente para menores níveis de pH urinário em pacientes com litíase cálcica. Pacientes com hipercalciúria e/ou hiperuricosúria apresentaram maiores valores de AO e menores de pH urinário.

Kidney stones: composition, frequency and relation to metabolic diagnosis

Nephrolithiasis is one of the most frequent urologic diseases. The aim of this paper is to study the composition and frequency of 8854 patient kidney stones and in a subset of them their metabolic risk factors to be related to their type of calculi. Physicochemical and crystallographic methods were used to assess kidney stone composition. In a subset of 715 patients, we performed an ambulatory metabolic protocol with diagnostic purposes. From the total sample 79% of stones were made of calcium salts (oxalate and phosphate), followed by uric acid stones in 16.5%, calcium salts and uric acid in 2%, other salts in 1.9% and cystine in 0.6%. Male to female ratio was almost three times higher in calcium salts and other types of stones, reaching a marked male predominance in uric acid stones, M/F 18.8 /1.0. The major risk factors for calcium stones are idiopathic hypercalciuria, followed by unduly acidic urine pH and hyperuricosuria. In uric acid stones unduly acidic urine pH and less commonly hyperuricosuria are the most frequent biochemical diagnosis. Our results show that analysis of kidney stones composition and the corresponding metabolic diagnosis may provide a scientific basis for the best management and prevention of kidney stone formation, as well as it may help us to study the mechanisms of urine stone formation.

La litiasis renal es una de las enfermedades urológicas más frecuentes. El objetivo de este trabajo fue estudiar la composición y frecuencia de 8854 cálculos renales y evaluar en un subgrupo de ellos la relación de los factores de riesgo metabólicos con el tipo de cálculo hallado. Se utilizaron métodos fisicoquímicos y cristalográficos para evaluar la composición de los cálculos renales. En un subgrupo de 715 pacientes, se pudo realizar un protocolo metabólico ambulatorio con fines diagnóstico. De la muestra total, 79.0% de los cálculos fueron de sales de calcio (oxalato y fosfato), seguido por cálculos de ácido úrico en 16.5%, sales de calcio y ácido úrico en 2.0%, otras sales en 1.9% y cistina en 0.6%. La relación hombre/mujer fue casi tres veces mayor en las sales de calcio y otros tipos de cálculos, alcanzando un marcado predominio en varones con cálculos de ácido úrico, M/F 18.8/1.0. Los principales factores de riesgo para los cálculos de calcio fueron la hipercalciuria idiopática, seguida del pH urinario excesivamente ácido y la hiperuricosuria. En los cálculos de ácido úrico el pH urinario excesivamente ácido y con menor frecuencia la hiperuricosuria fueron los diagnósticos más frecuentes. Nuestros resultados muestran que el análisis de la composición de los cálculos renales y el correspondiente diagnóstico metabólico pueden proporcionar una base científica para el mejor manejo y prevención en la formación de cálculos renales, así como que nos puede ayudar a estudiar los mecanismos de formación de los mismos.

Can a dual-energy computed tomography predict unsuitable stone components for extracorporeal shock wave lithotripsy?

PURPOSE: To assess the potential of dual-energy computed tomography (DECT) to identify urinary stone components, particularly uric acid and calcium oxalate monohydrate, which are unsuitable for extracorporeal shock wave lithotripsy (ESWL). MATERIALS AND METHODS: This clinical study included 246 patients who underwent removal of urinary stones and an analysis of stone components between November 2009 and August 2013. All patients received preoperative DECT using two energy values (80 kVp and 140 kVp). Hounsfield units (HU) were measured and matched to the stone component. RESULTS: Significant differences in HU values were observed between uric acid and nonuric acid stones at the 80 and 140 kVp energy values (p or =90%, calcium oxalate dihydrate group: monohydrate<90%). Significant differences in HU values were detected between the two groups at both energy values (p<0.001). CONCLUSIONS: DECT improved the characterization of urinary stone components and was a useful method for identifying uric acid and calcium oxalate monohydrate stones, which are unsuitable for ESWL.

Evaluation of low-dose dual energy computed tomography for in vivo assessment of renal/ureteric calculus composition

PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. RESULTS: A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.

Multimodal Treatments of Cystine Stones: An Observational, Retrospective Single-Center Analysis of 14 Cases

PURPOSE: To document the experiences of a single institution in evaluating the clinical courses and treatment outcomes of patients with cystine stones. MATERIALS AND METHODS: The clinical data of 14 patients with cystine stones who were treated at our institution from March 1994 to July 2012 were reviewed. These data included age at first visit, gender, family history, body mass index, presence of a single kidney, stone locations, stone burden, routine urinalysis, and culture. In addition, we also analyzed data on surgery, shock wave lithotripsy, medical treatment, stone recurrence or regrowth, and overall treatment success rates. RESULTS: The mean age of our patients at their first visit was 19.6+/-5.0 years, and eight patients were males. The median stone burden and mean urine pH before each surgery were 6.5 cm2 and 6.5+/-0.9, respectively. Two patients had a family history of cystine stones. Patients underwent surgery an average of 2.7 times. The median interval between surgeries was 27.3 months, and 1 open surgery, 12 percutaneous nephrolithotomies, and 25 ureterorenoscopies were performed. Potassium citrate or sodium bicarbonate was used in nine cases. D-Penicillamine was continuously used in three patients. Patients had an average incidence of 3.2 recurrences or regrowth of stones during the median follow-up period of 60.5 months. CONCLUSIONS: Patients with cystine stones have high recurrence or regrowth rates and relatively large stone burdens. Adequate treatment schedules must therefore be established in these cases to prevent possible deterioration of renal function.

Medical and Dietary Therapy for Kidney Stone Prevention

The prevalence of kidney stone disease is increasing, and newer research is finding that stones are associated with several serious morbidities. These facts suggest that emphasis needs to be placed not only on stone treatment but also stone prevention. However, there is a relative dearth of information on dietary and medical therapies to treat and avoid nephrolithiasis. In addition, studies have shown that there are many misconceptions among both the general community and physicians about how stones should be managed. This article is meant to serve as a review of the current literature on dietary and drug therapies for stone prevention.

Calcium renal lithiasis: metabolic diagnosis and medical treatment / Litiase renal cálcica: diagnóstico metabólico e tratamento médico

Calcium renal lithiasis is a frequent condition that affects the worldwide population and has a high recurrence rate. Different metabolic changes may trigger the onset of calcium stone disorders, such as hypercalciuria, hyperoxaluria, hyperuricosuria, hypocitraturia and others. There are also other very prevalent disorders that are associated with calcium calculi, such as arterial hypertension, obesity and loss of bone mineral density. A correct diagnosis needs to be obtained through examining the serum and urinary parameters of mineral metabolism in order to carry out adequate prevention and treatment of this condition. Once the metabolic diagnosis is known, it is possible to establish dietary and pharmacological treatment that may enable monitoring of the disease and prevent recurrence of stone formation. Some advances in treating this pathological condition have been made, and these include use of sodium alendronate in patients with calcium renal lithiasis and osteopenia/osteoporosis, or use of a combination of a thiazide with a bisphosphonate. In summary, calcium renal lithiasis often requires multidrug treatment with strict control and follow-up of patients.

Litíase renal cálcica é uma doença comum que afeta a população no mundo todo e tem alta taxa de recorrência. Diferentes alterações metabólicas podem desencadear o aparecimento de distúrbios de pedras de cálcio, como hipercalciúria, hiperoxalúria, hiperuricosúria, hipocitratúria e outros. Existem também doenças altamente prevalentes associadas à doença de cálculo de cálcio, como hipertensão, obesidade e perda de densidade óssea mineral. Para realizar prevenção e tratamento adequados, é necessário diagnóstico correto, examinando o metabolismo mineral sérico e urinário. Depois de conhecer o diagnóstico metabólico, é possível estabelecer um tratamento dietético e farmacológico que permita controlar a doença e prevenir a recorrência de cálculos biliares. Há alguns avanços no tratamento dessa doença e incluem o uso de alendronato de sódio em pacientes com nefrolitíase de cálcio e osteopenia/osteoporose, ou a combinação de um tiazídico com um bifosfonato. Em resumo, litíase renal cálcica exige, muitas vezes, um tratamento multidroga com rigorosos controle e acompanhamento de pacientes.

2D map of proteins from human renal stone matrix and evaluation of their effect on oxalate induced renal tubular epithelial cell injury

Purpose Proteins constitute a major portion of the organic matrix of human calcium oxalate (CaOx) renal stones and the matrix is considered to be important in stone formation and growth. The present study evaluates the effect of these proteins on oxalate injured renal epithelial cells accompanied by a 2D map of these proteins. Materials and Methods Proteins were isolated from the matrix of kidney stones containing CaOx as the major constituent using EGTA as a demineralizing agent. The effect of more than 3kDa proteins from matrix of human renal (calcium oxalate) CaOx stones was investigated on oxalate induced cell injury of MDCK renal tubular epithelial cells. A 2D map of >3kDa proteins was also generated followed by protein identification using MALDI-TOF MS. Results The >3kDa proteins enhanced the injury caused by oxalate on MDCK cells. Also, the 2D map of proteins having MW more than 3kDa suggested the abundance of proteins in the matrix of renal stone. Conclusion Studies indicate that the mixture of >3kDa proteins in the matrix of human renal stones acts as promoter of calcium oxalate crystal nucleation and growth as it augments the renal epithelial cell injury induced by oxalate. The effect of promoters masks the inhibitors in the protein mixture thereby leading to enhanced renal cell injury. 2D map throws light on the nature of proteins present in the kidney stones. .

Changes in Urinary Stone Composition in the Tunisian Population: A Retrospective Study of 1,301 Cases

BACKGROUND: Studies that evaluate the effect of age on stone composition are scarce. The aim of this study was to highlight the changes in epidemiological characteristics (stone composition and location) of urolithiasis according to patients' age. METHODS: We studied 1,301 urolithiasis patients with age ranging from 6 months to 92 yr (781 males and 520 females). Stone analysis was performed using a stereomicroscope and infrared spectroscopy to determine the morphological type and molecular composition of each stone. RESULTS: The annual average incidence of new stone formation was 31.7 per 100,000 persons. In 71.8% of cases, calculi were located in the upper urinary tract. Compared to other age groups, children and old men were more affected by bladder stones. Calcium oxalate monohydrate was the most frequent stone component, even though its frequency decreased with age (59.5% in young adults and 43.7% in the elderly, P<0.05) in favor of an increase in uric acid stones (11.5% in young adults and 36.4% in the elderly, P<0.05). Struvite stones were rare (3.8%) and more frequent in children than in adults. CONCLUSIONS: The analysis of these data showed that urinary stones in Tunisian patients are tending to evolve in the same direction as the stones in patients from industrialized countries.

Alkaline citrate reduces stone recurrence and regrowth after shockwave lithotripsy and percutaneous nephrolithotomy

OBJECTIVE: To evaluate the preventive effects of alkaline citrate on stone recurrence as well as stone growth post-ESWL or PCNL in patients with calcium-containing stones. MATERIALS AND METHODS: A total of 76 patients with calcium calculi who were stone-free or had residual stones less than 4 mm following ESWL and PCNL were enrolled. All patients were independently randomized into two groups. The treated group (N = 39) was given 81 mEq per day of oral potassium-sodium citrate (27 mEq three times a day), and the untreated group (N = 37) serving as controls. Blood, twenty-four hour urine analysis, and plain KUB were measured and compared at the baseline and after 12 months. RESULTS: At baseline, hypocitraturia was found in 20 of 39 patients (46.05 percent) of Group I and 15 of 37 patients (40.5 percent) of Group II. At 12 months, hypocitraturia was found in 3 of 39 (7.69 percent) and 14 of 37 (37.83 percent) of Group I and Group II, respectively (p = 0.007). At the 12 month follow-up, of the stone-free group, 92.3 percent of the treated group and 57.7 percent of the control group were still stone free. Of the residual stone group, 30.8 percent and 9.1 percent of treated and control group were stone-free, respectively. The increased stone size found in 7.7 percent and 54.5 percent of treated and control groups, respectively. CONCLUSION: Sodium-potassium citrate provides positive effects on stone-forming activities in calcium stone patients suffering from urolithiasis following treatment with ESWL and PCNL procedures at the 12-month follow-up.

Effect of biomolecules from human renal matrix of calcium oxalate monohydrate (CaOx) stones on in vitro calcium phosphate crystallization

PURPOSE: Investigate the activity of high and low molecular weight biomolecules present in the matrix of human calcium oxalate (CaOx) stones not only on the initial mineral phase formation of calcium and phosphate (CaP) but also on its growth and demineralization of the preformed mineral phase. MATERIALS AND METHODS: Surgically removed renal stones were analyzed by Fourier Transform Infra Red (FTIR) spectroscopy and only CaOx stones were extracted with 0.05M EGTA, 1 mM PMSF and 1 percent ß-mercaptoethanol. Renal CaOx stone extract was separated into > 10 kDa and < 10 kDa fractions by dialysis. Activity of both the fractions along with whole extract was studied on the three mineral phases of CaP assay system. RESULTS: It was interesting to observe that both high and low molecular weight biomolecules extracted from human renal matrix of calcium oxalate (CaOx) stones exhibited different roles in the three mineral phases of CaP. Whole extract exhibited inhibitory activity in all the three assay systems; however, mixed (stimulatory and inhibitory) activity was exhibited by the > 10 kDa and < 10 kDa fractions. SDS-PAGE analysis showed bands of 66 kDa, 80 kDa, 42 kDa in whole EGTA extract lane and > 10 kDa fraction lane. CONCLUSION: Both high and low molecular weight biomolecules extracted from human renal matrix of calcium oxalate (CaOx) stones have a significant influence on calcium and phosphate (CaP) crystallization.

Chemical and morphological analysis of kidney stones: a double-blind comparative study / Análise química e morfológica de cálculos renais: estudo comparativo duplo-cego

PURPOSE: To compare chemical to morphological kidney stone composition analysis based on a sample of 50 stones retrieved from patients at a nephrology service. METHODS: The chemical analysis was performed with a Bioclin® kit, while a 10-mm magnifying glass (10x; Prolabo, Paris, France) was employed in the morphological analysis. Findings obtained with the two methods were compared and classified as concordant (100 percent agreement), partly concordant (concordant for major components, discordant for minor components) or discordant (discordant for major components). RESULTS: In the chemical analysis, the most commonly observed major component was calcium (70 percent), followed by oxalate (66 percent), ammonium (56 percent), urate (28 percent) and carbonate (24 percent). In the morphological analysis, the most commonly observed major components were calcium phosphate and magnesium (32 percent each), followed by calcium oxalate monohydrate (24 percent), uric acid and urates (20 percent each), calcium oxalate dihydrate (18 percent) and cystine (6 percent). Infectious kidney stones were identified in 34 percent and 24 percent of cases by morphological and chemical analysis, respectively. Thirty-eight percent of the samples were classified as concordant, 52 percent were partly concordant and 10 percent were discordant. CONCLUSION: We suggest kidney stones be routinely submitted to both types of analysis for a better understanding of the mechanisms involved in lithogenesis.

OBJETIVO: Comparar a análise química com a análise morfológica de 50 cálculos urinários provenientes de pacientes em um serviço de nefrologia. MÉTODOS: A análise química foi realizada utilizando o kit da Bioclin®, enquanto que a morfológica foi realizada com auxílio de uma lupa de 10mm (Prolabo, Paris, France). A comparação entre as técnicas foi classificada em concordante (100 por cento de concordância), parcialmente concordante (componentes majoritários concordantes e minoritários discordantes) e discordante (discordância nos componentes majoritários). RESULTADOS: Na análise química os principais componentes majoritários foram cálcio (70 por cento), oxalato (66 por cento), amônio (56 por cento), urato (28 por cento) e carbonato (24 por cento). Na análise morfológica os principais componentes majoritários foram fosfato cálcico (PCa) e magnesiano-PCa (32 por cento), oxalato de cálcio monohidratado (24 por cento), ácido úrico e uratos (20 por cento), oxalato de cálcio dihidratado (18 por cento) e cistina (6 por cento). Cálculos de infecção foram identificados em 34 por cento e 24 por cento casos pela análise morfológica e química, respectivamente. Concordância total foi observada em 38 por cento, concordância parcial em 52 por cento e discordância em 10 por cento. CONCLUSÃO: Sugere-se a utilização simultânea das duas técnicas para melhor compreensão dos mecanismos litogênicos.

A nefrocalcina é uma proteína ligada à membrana?: uma hipótese bioquímica / Is nephrocalcin a membrane-bound protein?: a biochemical generate hypothesis

Introdução: A nefrocalcina (NC) é uma glicoproteína urinária que desempenha papel importante na inibição da cristalização do oxalato de cálcio (OxCa). A NC ocorre em pelo menos quatro isoformas (NC-A, B, C e D). As isoformas da NC são fosfoproteínas, mas a quantidade anormalmente elevada de resíduos de fosfato, em especial nas NC-C e D é intrigante. A NC poderia revestir a superfície de células epiteliais renais para evitar adesão de cristais de OxCa e conjugar fosfolípides da membrana em sua molécula. Objetivo: O objetivo deste trabalho foi identificar e caracterizar os fosfolipídios presentes na molécula de NC. Material e Métodos: A NC e suas isoformas foram isoladas da urina de indivíduo não portador de nefrolitíase. O conteúdo de fosfato foi determinado em cada isoforma. A taxa de inibição de crescimento de cristais de OxCa causada pela NC foi medida pelo consumo do ácido oxálico. A separação de lipídios, fosfolípides e proteínas foi realizada utilizando-se o método de separação Triton X-114. Resultados: Foram identificados os seguintes compostos: fosfatidilcolina, fosfoeta-nolamina, fosfatidilinositol, triglicérides e lipídios neutros. A composição de aminoácidos das isoformas da NC não se alterou. Após a extração com Triton X-114, os resíduos de fosfato das isoformas B, C e D diminuíram quase 1/10 do valor original e os da isoforma A não se alteraram. A constante de dissociação em direção ao oxalato de cálcio não foi alterada. Conclusão: Estes dados indicam a presença de fosfolípides típicos de membrana celular presentes na molécula de NC. A NC, incluindo-se todas as suas isoformas, pode ser uma proteína ligada à membrana, ao conjugar fosfolípides e revestir a superfície de células epiteliais tubulares.

Introduction: Nephrocalcin (NC) is a urinary glycoprotein that plays an important role in the inhibition of calcium oxalate crystallization. NC occurs in at least four isoforms (NC-A, -B, -C, and -D). NC isoforms are phosphoproteins, but the abnormally high phosphate residues, particularly in NC-C and NC-D, are intriguing. It is possible that NC molecules could coat the surface of renal epithelial cells for preventing attachment of calcium oxalate crystals, and could conjugate membrane phospholipids (PL). Our objective was to identify and characterize PL in NC. Material and Methods: NC and its four isoforms were isolated from non-stone forming urine. Phosphate contents were determined. Crystal growth inhibition rate of NC toward calcium oxalate monohydrate crystals (COM) was measured by decrease of oxalic acid. Phase separation of lipids and PL from proteins was carried out by a phase separation method using Triton X-114. Results: The following compounds were identified: phosphatidylcholine, phosphoethanolamine, phosphatidylinositol, triglycerides, and neutral lipids. Amino acid composition of the four NC isoforms before and after extraction did not change. After Triton X-114 extraction, phosphate residues in isoforms B, C, and D were decreased nearly 1/10 of the original value. However, isoform A phosphate residues showed no change. Dissociation constant toward calcium oxalate was not significantly altered. Conclusions: These data indicate the presence of typical membrane PL in NC molecule. NC, including all its isoforms, could be a membrane bound protein, conjugating membrane PL and coating the surface of the epithelial renal cells.

Study of calcium regulating hormones in calcium stone formers

The present study demonstrated that calcium stone formers possesses significant decrease in 1.25 [OH]2 Vit D; 24, 25 [OH]2 Vit D and Vit. D binding protein as compared to control. This finding is accompanied with high activity of alkaline phosphatase due to bone fraction elevation, and serum hypocalcaemia as well as hypophosphataemia. The interesting finding was the inactivation of superoxide dismutase [SOD] couple with hypercalciuria, and elevation of urine citric acid content

Shock wave lithotripsy treatment of radiolucent renal stones: a simple alternative

Objective: To evaluate a simple procedure for dealing with radiolucent renal pelvic stones larger than 2cm using combined ureteric catheter [for stone localization] and double-J stent [for prophylaxis of stein-strasse] prior to shock wave lithotripsy [SWL]

Methods: Thirty-five patients [21 males and 4 females] with single radiolucent stone in the renal pelvis were entered in this study in the period from Feb. 2003 to March 2007. The average stone size was 25mm [range from 20 to 30 mm]. Patients underwent initial ureteric catheter insertion followed by double-J stent and referred to SWL unit. The stone localized by contrast medium injected in the catheter throughout the lithotripsy session then the catheter was removed leaving the stent. Patients were followed up 10 days post lithotripsy by ultrasonography and I.V.P or non contrast spiral C.T scanning to detect the residual stones

Results: The success rate was 91% [32 patients] 10 days after lithotripsy. Three patients [9%] showed significant residual fragments. Those patients required oral chemolysis for stone dissolution. There was no adverse reactions of contrast medium and there was no significant complications intra or post-operatively

Conclusion: Shock wave lithotripsy for radiolucent renal pelvic stones with help of contrast medium injected through a ureteric catheter is a minimally invasive technique with a high success rate. It can be considered as a simple alternative to traditional treatment modalities for radiolucent stones

Predection of extracorporeal shock wave lithotrepsy outcome based on non-contrast helical computed tomography quantitative predictors

Objective: To assess the pretreatment non contrast helical computed tomography [NCCT] measurements, in the form of, stones Hounsfield unite [HU] and skin to stone distance [SSD] to define the effect of each on extracorporeal shock wave lithotripsy [ESWL] results

Patients and Methods: Twenty eight patients with single renal pelvic [10-20mm] or proximal ureteric stone [5-10mm] had pre-extracorporeal shock wave lithotripsy [ESWL] evaluation by non-contrast computed tomography [NCCT]. Stone attenuation value measured in Hounsfield Unit [HU] as well as skin to stone distance[SSD] was measured on selected NCCT image of interest for each patient, these measures were evaluated as predictors of ESWL outcome. Patients with renal pelvic stones received 3000 shocks per ESWL session while those with proximal ureteric stones received 4000 shocks per session, the maximum ESWL session number allowed were 3 .Patients were evaluated by plain X- ray of the kidney, ureter and bladder [KUB] after each ESWL session. Six weeks after ESWL treatment patients with stones greater than 3mm considered residual stone patients [10 out of 28 patients], while those with complete stone clearance or fragment 3mm or less considered stone- free patients [18 out of 28 patients].The stone attenuation value [HU] and skin to stone distance [SSD] in the stone-free and residual- stone patients group were compared

Results: The overall mean HU value for stone-free and residual-stone patients was significantly different 669 +/- 14.9 HU versus 962 +/- 11.5 HU respectively. The body mass index [BMI] as indicator of overweight or obesity status, go hand in hand with SSD and correlated well with each other, the mean SSD for stone free and residual stone patients were 9.3 +/- 2.7 and 11.4 +/- 3.01 cm respectively, which were statistically significantly different. Analysis of the data revealed that stones of greater than 900 HU were less likely to fragment and ESWL failure is probable[5 patients out of 8, 62.5%]. Furthermore, patients with SSD 10 cm or less had 91.6% stone free rate [11 out of 12 patients], while those with SSD greater than 10 cm had only 43.7% stone free rate [7 patients out of 16]

Conclusion: We concluded that, stone HU and the patients obesity status as expressed by the SSD are powerful predictors of NCCT for ESWL results, so we can save; unnecessary exposure to shock waves, time, effort and costs

Spectrum of stones composition: a chemical analysis of renal stones of patients visiting NMCTH.

A general observation of clinicians suggests that the prevalence ofurolithiasis is fairly high in Kathmandu but so far no systematic study has been undertaken here to explore the etiopathogenesis of disease in this region. In this preliminary communication, we present herewith the qualitative composition of 47 renal stones collected from surgical patients admitted to NMCTH over a period of 13 months (July 2005 to July 2006). All stones were of mixed type. Calcium was present in all stones. Oxalate, phosphate and uric acid were present in 95.7%, 87.2% and 34.0% patients respectively. The probable composition, as construed from analysis, suggests that calcium oxalate stones are predominant. Strikingly, the prevalence was very high in e"20 yrs age group.