Play it safe: renal function after bilateral flexible ureteroscopy for kidney stones.

PURPOSE: We searched for perioperative renal function deterioration risk factors in patients that underwent bilateral flexible ureteroscopy (fURS) for kidney stones. METHODS: From August 2016 to February 2020, symptomatic patients > 18 years old with bilateral kidney stones up to 20 mm in each side were prospectively studied. Serum creatinine samples were collected on admission to surgery, immediate postoperative (IPO), on POD 3, 10, and 30. Estimated glomerular filtration rate (eGFR) was calculated using Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) without a race coefficient. RESULTS: Thirty patients underwent bilateral fURS. Comparing to preoperative eGFR, median IPO and POD3 eGFR (p < 0.001) were significantly lower, and POD10 (p = 0.092) and POD30 (p = 0.648) were similar to preoperative eGFR. During follow-up, 22/30 (73.3%), 14/30 (46.7%), and 7/30 (23.3%) of the patients presented a decrease > 10% eGFR, > 20% eGFR, and > 30% eGFR, respectively. Multivariate analysis demonstrated that lower preoperative eGFR is a risk factor for eGFR < 60 mL/min/1.73 m2, p = 0.019 [1.021-1.263; 1.136]; ASA > 1 is a risk factor for decrease of eGFR > 10%, p = 0.028 [1.25-51.13; 8.00]; longer operative time is a risk factor for decrease of eGFR > 20%, p = 0.042 [1.00-1.05; 1.028]; and operative time ≥ 120 min is a risk factor for decrease of eGFR > 30%, p = 0.026 [0.016-0.773; 0.113]. CONCLUSIONS: Renal function suffers a reversible decrease after bilateral fURS. Our study suggests that adequate selection of patients and maintaining operative time < 120 min are relevant factors in preventing acute renal function deterioration following bilateral fURS.

Kidney stone matrix proteins: Role in stone formation.

Stone formation is induced by an increased level of urine crystallization promoters and reduced levels of its inhibitors. Crystallization inhibitors include citrate, magnesium, zinc, and organic compounds such as glycosaminoglycans. In the urine, there are various proteins, such as uromodulin (Tamm-Horsfall protein), calgranulin, osteopontin, bikunin, and nephrocalcin, that are present in the stone matrix. The presence of several carboxyl groups in these macromolecules reduces calcium oxalate monohydrate crystal adhesion to the urinary epithelium and could potentially protect against lithiasis. Proteins are the most abundant component of kidney stone matrix, and their presence may reflect the process of stone formation. Many recent studies have explored the proteomics of urinary stones. Among the stone matrix proteins, the most frequently identified were uromodulin, S100 proteins (calgranulins A and B), osteopontin, and several other proteins typically engaged in inflammation and immune response. The normal level and structure of these macromolecules may constitute protection against calcium salt formation. Paradoxically, most of them may act as both promoters and inhibitors depending on circumstances. Many of these proteins have other functions in modulating oxidative stress, immune function, and inflammation that could also influence stone formation. Yet, the role of these kidney stone matrix proteins needs to be established through more studies comparing urinary stone proteomics between stone formers and non-stone formers.

A simple assessment of the effect of strontium on the urinary excretion of calcium in Sprague Dawley rats.

This study was aimed at investigating the impact of varying concentrations of strontium (Sr) on calcium (Ca) excretion via the urine and determine its impact on kidney stone formation. Twenty adult male Sprague Dawley rats weighing between 200 and 300 g were selected. The rats were randomly divided into four groups of five. One group was used as a control group while the other three groups were experimental. The diet of the rats was modulated over a 12 week period to investigate the impact of Sr on the urinary excretion of Ca. Urinary samples were collected every 2 weeks from the rats. The rats were fed water ad libitum. After the study the rats were euthanised and their kidneys harvested. Urine and kidney samples from the rats were analysed using Total Reflection X-Ray Fluorescence (TXRF). In the urine excretion of Ca increased with increased intake of Sr in the diet. Sr excretion via the urine also increased with increased dietary intake. There was a correlation of 0.835 at the significance level of 0.01 between Ca and Sr in the urine. However, for the kidneys, the varying concentration of Sr did not impact the retention of Ca in the kidneys. There was increased retention of Sr in the kidneys with increased dietary intake. In this study an increase of Sr in the diet resulted in an increase in urinary excretion of Ca.

Comparison of the outcomes of flexible ureteroscopy and mini-percutaneous nephrolithotomy for the treatment of kidney stones: a matched-pair analysis

SUMMARY OBJECTIVE: Mini-percutaneous nephrolithotomy is a recent advancement in the field of kidney stone treatment; however, its role has not been completely established. We aimed to compare the outcomes of initial Mini-percutaneous nephrolithotomy and flexible ureteroscopy. METHODS: A retrospective review of consecutive mini-percutaneous procedures was performed. Inclusion criteria were as follows: all percutaneous nephrolithotomy procedures performed with an access sheath up to 24Fr, kidney stone burdens up to 1550 mm3; and the presence of postoperative computed tomography (for control). The data collected for Mini-percutaneous nephrolithotomy procedures were paired 1:2 with patients treated with flexible ureteroscopy for stones between 100 and 1550 mm3, and with postoperative computed tomography for control. A 14Fr Mini-percutaneous nephrolithotomy set was used. The stone-free rate was defined as the absence of fragments on the control computed tomography, whereas success was limited to 2-mm residual fragments. Statistical analysis was performed using SPSS version 19. RESULTS: A total of 63 patients met the inclusion criteria (42 with flexible ureteroscopy and 21 with mini-percutaneous nephrolithotomy). Demographic data were comparable. The stone-free rate and success were similar between the groups (76.2 vs. 66.7%, p=0.42 and 90.5 vs. 85.7%, p=0.57). The complication rate was also similar (26.1 vs. 9.6%, p=0.188), but Mini-percutaneous nephrolithotomy had longer hospitalization and fluoroscopy time (p=0.001 in both). CONCLUSIONS: Our initial study of Mini-percutaneous nephrolithotomy showed that it is a promising procedure, with outcomes similar to flexible ureteroscopy, but with higher inpatient numbers and fluoroscopy times. A larger study population size and better equipment may improve the outcomes of mini-percutaneous nephrolithotomy.

Predictive factors for success after supine percutaneous nephrolithotomy: an analysis of 961 patients

SUMMARY OBJECTIVE: The aim of this study was to evaluate the predictive factors for success following percutaneous nephrolithotomy in the supine position. METHODS: Patients who underwent percutaneous nephrolithotomy in the supine position from June 2011 to October 2018 were evaluated. Age, sex, body mass index, the American Society of Anesthesiologists physical status classification, hemoglobin level, number of previous surgeries, stone size, and the Guy's Stone Score were analyzed. Success was considered if no fragments were observed on the computed tomography scan on the first postoperative day. Univariate and multivariate analyses were performed to determine significant parameters. RESULTS: We evaluated 961 patients; of them, 483 (50.2%) underwent previous stone-related surgery, and 499 (51.9%) had Guy's Stone Score 3 or 4. The overall success rate in a single procedure was 40.7%, and complication rate was 13.7%. The univariate analysis showed that the maximum diameter of the stone (25.10±10 mm; p<0.001), previous percutaneous nephrolithotomy (OR 0.52; p<0.001), number of previous percutaneous nephrolithotomy (OR 0.15; p<0.001), the Guy's Stone Score (OR 0.28; p<0.001), and the number of tracts (OR 0.32; p<0.001) were significant. In the multivariate analysis, the number of previous percutaneous nephrolithotomy (OR 0.54; p<0.001) and the Guy's Stone Score (OR 0.25; p<0.001) were statically significant. CONCLUSIONS: Guy's Stone Score and the number of previous percutaneous nephrolithotomy are predictors of success with the supine position. Complex cases and with previous percutaneous interventions may require technical improvements to achieve higher stone-free rates.

Efficacy of ultra-mini percutaneous nephrolithotomy and retrograde intrarenal surgery in the treatment of 2-3 cm lower calyceal stones / Eficacia de la nefrolitotomía percutánea ultramini y la cirugía intrarrenal retrógrada en el tratamiento de cálculos caliceales inferiores de 2-3 cm

Abstract We aimed to compare the efficacy and safety of ultra-mini percutaneous nephrolithotomy (UMP) and retrograde intrarenal surgery (RIRS) for the management of lower calyceal stones. A group of 136 patients with a single lower calyceal stone (2-3 cm in diameter) was divided into the UMP or RIRS groups. The average operation time in the RIRS group was significantly longer than that in the UMP group, and the intraoperative blood loss in the former was markedly less than that in the latter. Besides, in the RIRS group, the decreased value of postoperative Hb was obviously lower, the postoperative hospital stay was evidently shorter, and the total hospitalization expenses were markedly less than those in UMP group were. Moreover, the success rate of the first-stage lithotripsy in the UMP group was notably higher than that in RIRS group. The RIRS group had an obviously lower VAS score but a markedly higher BCS score than the UMP group six hours after surgery. At 24 h after operation, the levels of serum CRP, TNF-α and IL -6 in patients in both groups were remarkably increased, and they were evidently lower in the RIRS group than those in the UMP group were. Three days after surgery, the levels of serum CRP, TNF-α and IL -6 were notably lower in the UMP group than those in RIRS group were. RIRS and UMP are safe and effective in the treatment of 2-3 cm lower calyceal stones. The first-stage UMP is characterized by a high stone-free rate (SFR), short operation time and low postoperative infection risk, while RIRS is associated with less blood loss and low total expenses.

Resumen Nuestro objetivo fue comparar la eficacia y seguridad de la nefrolitotomía percutánea ultramini (UMP) y la cirugía intrarrenal retrógrada (CRIR) en el manejo quirúrgico de los cálculos caliceales inferiores. Un grupo de 136 pacientes con un solo cálculo calicial inferior (2-3 cm de diámetro) se dividió en un grupo UMP o un grupo CRIR. El tiempo de operación promedio en el grupo CRIR fue significativamente más largo que en el grupo UMP, y la pérdida de sangre intraoperatoria en el primero fue marcadamente menor que en el segundo. Además, en el grupo CRIR, el valor disminuido de la Hb postoperatoria fue obviamente menor, la estancia hospitalaria postoperatoria fue evidentemente más corta y los gastos totales de hospitalización fueron notablemente menores que los del grupo UMP. Además, la tasa de éxito de la litotricia de primera etapa en el grupo UMP fue notablemente más alta que en el grupo CRIR. El grupo CRIR tuvo una puntuación VAS obviamente más baja pero una puntuación BCS marcadamente más alta que el grupo UMP a seos horas después de la operación. A las 24 h después de la operación, los niveles séricos de PCR, TNF-α e IL -6 en los pacientes de ambos grupos aumentaron notablemente y fueron evidentemente más bajos en el grupo CRIR que en el grupo UMP. Tres días después de la operación, los niveles séricos de PCR, TNF-α e IL -6 fueron notablemente más bajos en el grupo UMP que en el grupo CRIR. Los procedimientos CRIR y el UMP son seguros y eficaces en el tratamiento de cálculos caliciales inferiores de 2-3 cm. El UMP de primera etapa se caracteriza por tener una tasa libre de cálculo (SFR) alta, un tiempo de operación corto y un riesgo de infección posoperatorio bajo, y el RIRS se caracteriza por una menor pérdida de sangre y gastos totales bajos.

Beyond kidney stones: Why pediatricians should worry about hypercalciuria.

The incidence of urolithiasis (UL) is increasing, and it has become more common in children and adolescents over the past few decades. Hypercalciuria is the leading metabolic risk factor of pediatric UL, and it has high morbidity, with or without lithiasis as hematuria and impairment of bone mass. The reduction in bone mineral density has already been described in pediatric idiopathic hypercalciuria (IH), and the precise mechanisms of bone loss or failure to achieve adequate bone mass gain remain unknown. A current understanding is that hypercalciuria throughout life can be considered a risk of change in bone structure and low bone mass throughout life. However, it is still not entirely known whether hypercalciuria throughout life can compromise the quality of the mass. The peak bone mass is achieved by late adolescence, peaking at the end of the second decade of life. This accumulation should occur without interference in order to achieve the peak of optimal bone mass. The bone mass acquired during childhood and adolescence is a major determinant of adult bone health, and its accumulation should occur without interference. This raises the critical question of whether adult osteoporosis and the risk of fractures are initiated during childhood. Pediatricians should be aware of this pediatric problem and investigate their patients. They should have the knowledge and ability to diagnose and initially manage patients with IH, with or without UL.

In vitro effects of two bioactive compounds, gallic acid and methyl gallate, on urolithiasis.

INTRODUCTION AND OBJECTIVES: This study aimed to evaluate the role of two widely distributed natural phenolic compounds, gallic acid (GA) and methyl gallate (MG), in an in vitro model of urolithiasis, by using the methodology of calcium oxalate (CaOx) crystals formation, which is the most common type of urinary or kidney stones. MATERIAL AND METHODS: The compounds GA and MG were subjected to anti-crystallization activities in different concentrations (0.003-0.03 mg/mL), and the quantity and morphology of crystals were determined by microscopy after 60 min. RESULTS: GA inhibited about 44-57% of the total CaOx crystals formation, while MG inhibited about 48.35%, when compared to vehicle-exposed samples (distilled water; negative control group). GA and MG exposure inhibited monohydrate type calculi formation, which is considered the most common and harmful crystal category. The compounds also decreased absorbance, which in turn is related to reduced CaOx aggregation and precipitation. CONCLUSIONS: Altogether, this study shows, for the first time, that GA and MG are promising compounds with antiurolithiatic properties, opening new perspectives for future in vivo evaluations of the potential of these compounds in the treatment and/or prevention of urinary or kidney stones.

In vitro effects of 2 bioactive compounds, gallic acid and methyl gallate, on urolithiasis. / Efecto in vitro de 2 compuestos bioactivos, el ácido gálico y el galato de metilo, sobre la urolitiasis.

INTRODUCTION AND OBJECTIVES: This study aimed to evaluate the role of 2 widely distributed natural phenolic compounds, gallic acid (GA) and methyl gallate (MG), in an in vitro model of urolithiasis, by using the methodology of calcium oxalate crystals formation, which is the most common type of urinary or kidney stones. MATERIAL AND METHODS: The compounds GA and MG were subjected to anti-crystallization activities in different concentrations (0.003-0.03mg/mL), and the quantity and morphology of crystals were determined by microscopy after 60min. RESULTS: GA inhibited about 44-57% of the total calcium oxalate crystals formation, while MG inhibited about 48.35%, when compared to vehicle-exposed samples (distilled water; negative control group). GA and MG exposure inhibited monohydrate type calculi formation, which is considered the most common and harmful crystal category. The compounds also decreased absorbance, which in turn is related to reduced calcium oxalate crystals aggregation and precipitation. CONCLUSIONS: Altogether, this study shows, for the first time, that GA and MG are promising compounds with antiurolithiatic properties, opening new perspectives for future in vivo evaluations of the potential of these compounds in the treatment and/or prevention of urinary or kidney stones.

Gallic Acid-Chitosan Conjugate Inhibits the Formation of Calcium Oxalate Crystals.

It has recently been shown that chitosan (Chit) induces the formation of calcium oxalate (CaOx) crystals, which are mainly responsible for the appearance of kidney stones, and this might limit the use of Chit in vivo. Here, Chit was conjugated with gallic acid (Chit-Gal) to decrease the formation of CaOx crystal. This conjugation was confirmed by FTIR and NMR analyses. Chit-Gal contains 10.2 ± 1.5 mg GA per g of Chit. Compared to the control group, Chit increased the number of crystals by six-fold, mainly in the number of monohydrated CaOx crystals, which are the most harmful CaOx crystals. In addition, Chit increased the zeta potential (ζ) of CaOx crystals by three-fold, indicating that Chit was associated with the crystals. These alterations were abolished when Chit-gal was used in these tests. As oxidative stress is related to renal calculus formation, Chit and Chit-Gal were also evaluated as antioxidants using total antioxidant Capacity (TAC), reducing power, ferrous chelation, and copper chelation tests. Chit-gal was more efficient antioxidant agent in TAC (2 times), in ferrous chelation (90 times), and in reducing Power (5 times) than Chit. Overall, Chit-gal has higher antioxidant activity than Chit, does not induce the formation of CaOx crystals. Thus, Chit-Gal has potential to be used as a chit substitute.

Rearrangement of the Guy's stone score improves prediction of stone-free rate after percutaneous nephrolithotomy.

OBJECTIVE: We propose a modification of the original Guy's Stone Score (GSS) to hold on 20 % of prognostic discrimination among groups which makes this score a more reliable resource for risk assessment in patients undergoing percutaneous nephrolithotomy (PCNL). MATERIAL AND METHODS: Historical cohort of 126 patients undergoing PCNL from December 2010 to November 2014 was included in the survey. Every patient was classified according to the original GSS. For the new classification of Guy Stone Score (GSS-M) all of the subgroups included in the scale were analyzed individually and then ranked from better to worst according to the postoperative stone- free rates (SFRs). This ranking led us to reclassify all the original subgroups, clustering them in three new categories according to their SFRs as subgroups of good, intermediate and poor prognosis, trying to achieve at least 20% of prognostic discrimination among the groups. RESULTS: Hundred and twenty-six PCNL procedures were evaluated, but only 124 were included for statistical analysis and classified based on SFR according to the GSS as follows: 76% for grade 1, 71% for grade 2, 55% for grade 3 and 20% for grade 4. The SFRs were also assessed for the GSS-M obtaining the following predictive values as 93%, 67% and 44% for the good, intermediate and poor prognostic groups, respectively. The prognostic difference among the GSS-M groups was always >20% (p<0.05). CONCLUSION: The original GSS has limitations to predict SFR because of its poor discrimination power among prognostic groups. This rearrangement improves prediction of SFR and better discriminates risk groups in PCNL.

Is a safety guidewire needed for retrograde ureteroscopy? / Fio guia de segurança é necessário na ureteroscopia?

Summary Introduction: It is generally advised to have a safety guidewire (SGW) present during ureteroscopy (URS) to manage possible complications. However, it increases the strenght needed to insert and retract the endoscope during the procedure, and, currently, there is a lack of solid data supporting the need for SGW in all procedures. We reviewed the literature about SGW utilization during URS. Method: A review of the literature was conducted through April 2017 using PubMed, Ovid, and The Cochrane Library databases to identify relevant studies. The primary outcome was to report stone-free rates, feasibility, contraindications to and complications of performing intrarenal retrograde flexible and semi-rigid URS without the use of a SGW. Results: Six studies were identified and selected for this review, and overall they included 1,886 patients where either semi-rigid or flexible URS was performed without the use of a SGW for the treatment of urinary calculi disease. Only one study reported stone-free rates with or without SGW at 77.1 and 85.9%, respectively (p=0.001). None of the studies showed increased rates of complications in the absence of SGW and one of them showed more post-endoscopic ureteral stenosis whenever SGW was routinely used. All studies recommended utilization of SGW in complicated cases, such as ureteral stones associated with significant edema, ureteral stricture, abnormal anatomy or difficult visualization. Conclusion: Our review showed a lack of relevant data supporting the use of SGW during retrograde URS. A well-designed prospective randomized trial is in order.

Resumo Introdução: O uso de fio guia de segurança (FGS) costuma ser recomendado para a realização de ureteroscopia para prevenir e solucionar complicações durante o procedimento. Seu uso, porém, aumenta a força necessária para manipular o aparelho endoscópico dentro da luz ureteral e, atualmente, existe uma carência de dados consistentes que indiquem o uso do FGS em todos os procedimentos. Método: Uma revisão da literatura foi realizada em abril de 2017 utilizando as ferramentas PubMed, Ovid e The Cochrane Library para identificar estudos relevantes. O desfecho primário da análise foi reportar taxas de resolução dos cálculos, viabilidade, contraindicações e complicações relacionadas ao não uso do FGS. Resultados: Seis estudos foram incluídos na análise, totalizando 1.886 pacientes, nos quais foi realizada ureteroscopia semirrígida ou flexível sem o uso do FGS no tratamento de cálculos renais ou ureterais. Somente um estudo relatou taxa livre de cálculos com ou sem FGS, sendo 77,1 e 85,9%, respectivamente (p=0.001). Todos os estudos mostraram não haver aumento da taxa de complicação na ausência do FGS e um deles relatou aumento de estenose ureteral pós-endoscopia no grupo que utilizou o FGS. Todos os estudos recomendam o uso do FGS em casos complicados, como cálculos ureterais associados a edema de mucosa, estenose ureteral, anomalias anatômicas ou dificuldade de visualização do cálculo. Conclusão: Nossa revisão mostrou que faltam dados relevantes para justificar o uso do FGS durante a ureteroscopia.

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.

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.

Litíase urinária / Urinary lithiasis

A litíase urinária pode ser considerada uma doença crônica pela sua taxa de recorrência de 50% dos casos em até 10 anos de seguimento clínico. Como uma urgência médica, a ocorrência da cólica renoureteral manifestada pela súbita obstrução do trato urinário leva muitos pacientes ao pronto atendimento hospitalar e em determinadas situações com elevado risco quando associado à infecção do trato urinário e insuficiência renal.Elaboramos uma completa revisão sobre o assunto abordando desde a sua fisiopatologia até como realizar o tratamento atual da doença litiásica e sua prevenção.

Review on renal recovery after anatrophic nephrolithotomy: Are we really healing our patients?

The main goals for urinary stone treatment are to preserve renal function, reduce or avoid complications related to calculi, and to render the patient free of calculi as soon as possible. Anatrophic nephrolithotomy (ANL) is a valid and useful alternative for conventional staghorn calculi excision. Although excellent stone free rates can be achieved with ANL there are some drawbacks that may be of concern. Morbidity related to intraoperative and postoperative complications is one of them. Another, great concern is the possibility of reduction on renal function related to the procedure itself. This may be related to nephron injury during nephrotomy and parenchymal closure or to ischemic injury. In this review we assess functional results after anatrophic nephrolithotomy.

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.

Percutaneous nephrolithotomy: Current concepts.

Percutaneous nephrolithotomy (PNL) is the procedure of choice for large renal stones. Since its introduction in 1976, many aspects of the operative technique and the endoscopic equipments have had constant evolution, increasing the success rates of the procedure. We performed a literature search using Entrez Pubmed from January 2000 to July 2007 concerning PNL and many aspects related to all steps of the procedure.We could verify that PNL in supine position has been proved as an acceptable option, but more worldwide experience is necessary. Urologists must be trained to gain their own renal tract access. Minipercutaneous PNL still needs equipments improvements for better results. Tubeless PNL is increasing in popularity and different tract sealants have been studied. Medical prevention is proved to be effective against stone recurrence and should be always used after PNL.Although the evolution of the technique in the last 20 years, urologists must continue to improve their skills and develop new technologies to offer to the patients more and more a safe and effective option to treat large renal stones.