Papatsoris Athanasios, Geavlete Bogdan, Radavoi George Daniel, Alameedee Mohammed, Almusafer Murtadha, Ather M Hammad, Budia Alberto, Cumpanas Alin Adrian, Kiremi Murat Can, Dellis Athanasios, Elhowairis Mohamed, Galán-Llopis Juan Antonio, Geavlete Petrisor, Guimerà Garcia Jordi, Isern Bernat, Jinga Viorel, Lopez Juan Manuel, Mainez Juan Antonio, Mitsogiannis Iraklis, Mora Christian Jorge, Moussa Mohammad, Multescu Razvan, Oguz Acar Yusuf, Petkova Kremera, Piñero Adrià, Popov Elenko, Ramos Cebrian Maria, Rascu Stefan, Siener Roswitha, Sountoulides Petros, Stamatelou Kyriaki, Syed Jaffry, Trinchieri Alberto
National Kapodistrian University of Athens, 2nd University Urology Clinic, Sismanoglio Hospital, Athens.
"Carol Davila" University of Medicine and Pharmacy, "Saint John" Emergency Clinical Hospital, Bucharest.
Arch Ital Urol Androl. 2025 Jun 30;97(2):14085. doi: 10.4081/aiua.2025.14085.
The formation of kidney stones is a complex biologic process involving interactions among genetic, anatomic, dietary, and environmental factors. Traditional lithogenic models were based on urine supersaturation in relation to the activity of crystallization promoters and inhibitors. However, modern research has added new principles such as the "renal epithelial cell response" and the role of inflammation and oxidative stress leading to the development of a "multi-hit hypothesis". A strong correlation between urinary stones and kidney damage has been well demonstrated by both cohort and case-control studies. The main contributors to chronic kidney damage associated with urinary stones include crystal deposition within the renal parenchyma, associated comorbidities, repeated obstructive and infectious episodes, as well as the potential adverse effects of stone removal procedures. Most hereditary stones may cause high urinary saturation levels promoting obstruction of the Bellini ducts and consequent glomerulosclerosis and interstitial fibrosis in the cortex. These include hereditary hypercalciurias, primary hyperoxalurias, cystinuria, adenine phosphoribosyltransferase (APRT) deficiency (associated with 2,8-dihydroxyadenine lithiasis) and xanthinuria. Complete distal renal tubular acidosis occurs in childhood and presents deafness, rickets, and a short life expectancy. The incomplete form usually manifests in adulthood, primarily with recurrent urinary lithiasis, and less frequently with nephrocalcinosis. In all stone formers stone analysis and a basic metabolic evaluation, including blood biochemistry, urine sediment examination, urinary pH and culture are mandatory, in contrast high-risk stone formers require a more specific metabolic evaluation, including a 24-hour urine sample to measure calcium, phosphate, citrate, oxalate, uric acid, magnesium, sodium and proteinuria. The morpho compositional analysis of kidney stones offers essential insights beyond merely identifying their predominant chemical component. This approach reveals key aspets of the stone formation, such as nucleation sites, crystal growth patterns, and the presence of specific lithogenic processes. The ideal analytical protocol combines stereoscopic microscopy (StM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and, when necessary, Fourier-transform infrared spectroscopy (FTIR). Recurrence prevention and managing residual fragments require complementary strategies such as lifestyle modifications, dietary interventions, and pharmacological therapies. Among pharmacological options, alkaline citrate salts, particularly potassium citrate, are widely used due to their ability to modify urinary chemistry and inhibit stone formation. Recently, novel molecules have been introduced into the management of renal stone disease. Phytate a naturally occurring polyphosphorylated carbohydrate, exibits a potent inhibitory effect on calcium salt's nucleation, growth, and aggregation. Theobromine, another natural compound, has been shown to effectively inhibit uric acid crystallization. The co-administration of urinary alkalinizing agents, such as potassium citrate, alongside theobromine has been proposed as a therapeutic strategy to optimize uric acid solubility and to reduce the risk of excessive alkalinization and subsequent sodium urate precipitation. Struvite stones are caused by urinary tract infection with urease- producing microorganisms. Their treatment requires specific measures including complete surgical stone removal, short or long-term antibiotic treatment, to maintain urinary acidification to a pH below 6.2, and a urine volume of at least 2 litres/24 hours. L-methionine has been shown to effectively lower urine pH and the relative supersaturation of struvite. An essential aspect of medical management of urinary stone disease is treatment adherence, which depends on perceived benefit, treatment duration, and side effect profile. The side effects of citrate treatment are mild gastrointestinal disorders whereas thiazide diuretics tend to cause hypokalemia-related symptoms and less frequent metabolic and dermatologic side effects. Urease inhibitors for struvite stones and drugs used to enhance cystine solubility are more frequently associated with side effects. The use of smartphone applications can support patients by promoting adequate hydration, adherence to dietary recommendations, and compliance with prophylactic medication. Endoscopic techniques currently play a prevalent role in the removal of renal stones, while extracorporeal shock wave lithotripsy is today marginally used for specific indications. Different technical modalities can be used for percutaneous nephrolithotomy (PCNL), each with its own advantages and disadvntages (standard vs. mini, prone vs. supine, fluoroscopic vs ultrasound-guided). Flexible ureteroscopy or retrograde intrarenal renal surgery (RIRS) has extended its indications due to technological advancements in endoscopes and their accessories. The availability of new laser technologies (thulium fiber laser and pulse-modulated Ho:YAG laser) has enhanced stone fragmentation and dusting capabilities. However, their use exposes the renal parenchyma to high temperatures and pressures which could potentially contribute to renal damage. Factors influencing heat release include laser type and settings, exposure time, stone location, fiber-to-stone distance, irrigation volume and fluid circulation. Reduction of heat release can be achieved by limiting the laser settings to reasonable values or by improving fluid circulation with use of ureteral access sheaths, especially those navigable and equipped with suction. High intrarenal pressure is also closely associated with renal damage. Sustained high pressure or even pressure spikes may increase this risk, highlighting the importance of real-time pressure monitoring through sensors integrated on guidewires, scopes, access sheath and use of innovative platforms regulating irrigation/suction systems. Direct In-Scope Suction (DISS) system was developed to control intrarenal pressure and facilitate the removal of residual fragments. Flexible and Navigable Suction Ureteral Access Sheath (FANS-UAS) is a flexi-bendable UAS equipped with suction capabilities combining mechanical flexibility with continuous irrigation management and stone clearance mechanisms. Ultra-thin scopes (7.5 F) make it easy to perform RIRS without the need for pre-placed double-J stents or with a 9 F sheath achieving more space for stone fragments expulsion or infusion. All these technological advancements have enhanced the efficacy of fURS or RIRS which can be an alternative treatment (salvage fURS) when standard stone management techniques, such as percutaneous nephrolithotomy (PCNL), are contraindicated or fail. Salvage fURS has shown favorable outcomes in complex or high-risk cases, including patients with coagulopathies, morbid obesity, renal anatomical abnormalities (e.g., horseshoe or pelvic kidneys), urinary diversion, calyceal diverticula, and altered urinary tracts. In such scenarios it demonstrated favorable outcomes with stone-free rates ranging from 55.6% to 64% for stones > 2 cm. Although non-invasive, extracorporeal and endoscopic treatments for renal and ureteral stones carry a risk of complications that can be classified according to the Clavien-Dindo system. The complication rate after SWL was estimated at 18.43% for Clavien grade I-II complications (pain, hematuria) and 2.48% for Clavien III-IV complications (hematoma, sepsis). The most frequent complication after RIRS is fever or urinary tract infection observed in 0.2-15% (with 0.1-4.3% of cases of urinary sepsis). Complications after PCNL are more frequent and may include moderate events (hemorrhage requiring transfusion 2-7%, urosepsis 1-2%, bowel injury < 1%) as well as severe events (arteriovenous fistula 0.5-1%, thoracic complications < 1% , loss of access tract 1-3%, death < 0.5%). The risk of bleeding complications is significantly increased in patients on antithrombotic therapy. A personalized, interdisciplinary approach enables optimal decision-making in balancing antithrombotic therapy with surgical safety during urological stone interventions Finally, it must be considered that endourological procedures can be harmful to the surgeons themselves and their team due to exposure to ionizing radiation. For this reason, procedures must be carried out in strict accordance with safety guidelines and regulations to minimize radiation exposure. Safety is vital in any surgical intervention, with efficacy being the next most critical consideration. However, cost-effectiveness should be also considered. Endourology involves high costs largely due to the use of sophisticated equipment that requires frequent renewal due to the continuous rapid technological evolution. Using disposable devices brings numerous benefits but also leads to a further increase in costs. Finally, in the cost-benefit assessment, the rate of reintervention associated with some types of procedures must be considered.
肾结石的形成是一个复杂的生物学过程,涉及遗传、解剖、饮食和环境因素之间的相互作用。传统的结石形成模型基于尿液过饱和度与结晶促进剂和抑制剂活性的关系。然而,现代研究增加了新的原理,如“肾上皮细胞反应”以及炎症和氧化应激在导致“多重打击假说”发展中的作用。队列研究和病例对照研究均充分证明了尿路结石与肾损伤之间存在密切关联。与尿路结石相关的慢性肾损伤的主要促成因素包括肾实质内的晶体沉积、相关合并症、反复的梗阻和感染发作,以及结石清除手术的潜在不良影响。大多数遗传性结石可能导致高尿饱和度,从而促进乳头管梗阻,进而导致皮质肾小球硬化和间质纤维化。这些包括遗传性高钙尿症、原发性高草酸尿症、胱氨酸尿症、腺嘌呤磷酸核糖转移酶(APRT)缺乏症(与2,8 - 二羟基腺嘌呤结石症相关)和黄嘌呤尿症。完全性远端肾小管酸中毒在儿童期发病,表现为耳聋、佝偻病和预期寿命短。不完全形式通常在成年期出现,主要表现为复发性尿路结石,较少见肾钙质沉着症。对于所有结石患者,结石分析和基本代谢评估是必需的,包括血液生化、尿沉渣检查、尿pH值和培养;相比之下,高风险结石患者需要更具体的代谢评估,包括24小时尿样以测量钙、磷、柠檬酸盐、草酸盐、尿酸、镁、钠和蛋白尿。肾结石的形态成分分析不仅能识别其主要化学成分,还能提供重要见解。这种方法揭示了结石形成的关键方面,如成核位点、晶体生长模式以及特定结石形成过程的存在。理想的分析方案结合了立体显微镜(StM)、扫描电子显微镜与能量色散X射线光谱(SEM - EDS),必要时还包括傅里叶变换红外光谱(FTIR)。预防复发和处理残留碎片需要综合策略,如生活方式改变、饮食干预和药物治疗。在药物选择中,碱性柠檬酸盐,特别是柠檬酸钾,因其能够改变尿液化学性质并抑制结石形成而被广泛使用。最近,新型分子已被引入肾结石疾病的管理中。植酸是一种天然存在的多磷酸化碳水化合物,对钙盐的成核、生长和聚集具有强大的抑制作用。另一种天然化合物可可碱已被证明能有效抑制尿酸结晶。有人提出将尿路碱化剂,如柠檬酸钾,与可可碱联合使用作为一种治疗策略,以优化尿酸溶解度并降低过度碱化和随后尿酸钠沉淀的风险。磷酸镁铵结石由产脲酶微生物引起的尿路感染所致。其治疗需要采取特定措施,包括完全手术清除结石、短期或长期抗生素治疗,以将尿液酸化维持在pH值低于6.2,并使尿量至少达到2升/24小时。L - 蛋氨酸已被证明能有效降低尿液pH值和磷酸镁铵的相对过饱和度。尿路结石疾病医疗管理的一个重要方面是治疗依从性,这取决于感知到的益处、治疗持续时间和副作用情况。柠檬酸盐治疗的副作用是轻度胃肠道紊乱,而噻嗪类利尿剂往往会导致与低钾血症相关的症状,以及较少见的代谢和皮肤副作用。用于磷酸镁铵结石的脲酶抑制剂和用于提高胱氨酸溶解度的药物更容易出现副作用。使用智能手机应用程序可以通过促进充足的水分摄入、遵守饮食建议和遵医嘱预防性用药来帮助患者。目前,内镜技术在肾结石清除中发挥着重要作用,而体外冲击波碎石术如今仅用于特定适应症。经皮肾镜取石术(PCNL)可采用不同的技术方式,每种方式都有其自身的优缺点(标准与迷你、俯卧与仰卧、透视与超声引导)。由于内镜及其附件的技术进步,软性输尿管镜或逆行肾内手术(RIRS)的适应症得到了扩展。新型激光技术(铥光纤激光和脉冲调制钬激光)的出现增强了结石破碎和粉末化能力。然而,它们的使用会使肾实质暴露于高温和高压下,这可能会导致肾损伤。影响热量释放的因素包括激光类型和设置、暴露时间、结石位置、光纤与结石的距离、冲洗液量和液体循环。通过将激光设置限制在合理值或使用输尿管通路鞘(特别是那些可导航且配备抽吸功能的鞘)改善液体循环,可以减少热量释放。高肾内压也与肾损伤密切相关。持续的高压甚至压力峰值可能会增加这种风险,这凸显了通过集成在导丝、内镜、通路鞘上的传感器进行实时压力监测以及使用创新平台调节冲洗/抽吸系统的重要性。直接内镜下抽吸(DISS)系统的开发是为了控制肾内压并便于清除残留碎片。可弯曲且可导航的抽吸输尿管通路鞘(FANS - UAS)是一种可弯曲的输尿管通路鞘,配备有抽吸功能,将机械灵活性与持续冲洗管理和结石清除机制相结合。超薄内镜(7.5F)使无需预先放置双J支架或使用9F鞘进行RIRS变得容易,从而为结石碎片排出或灌注提供更多空间。所有这些技术进步都提高了软性输尿管镜检查(fURS)或RIRS的疗效,当标准的结石管理技术,如经皮肾镜取石术(PCNL)禁忌或失败时,它们可以作为替代治疗(挽救性fURS)。挽救性fURS在复杂或高风险病例中显示出良好的效果,包括患有凝血障碍、病态肥胖、肾解剖异常(如马蹄肾或盆腔肾)、尿路改道、肾盏憩室和尿路改变的患者。在这种情况下,对于直径>2 cm的结石,其结石清除率为55.6%至64%,显示出良好的效果。尽管肾和输尿管结石的非侵入性、体外和内镜治疗存在并发症风险,但可根据Clavien - Dindo系统进行分类。体外冲击波碎石术(SWL)后Clavien I - II级并发症(疼痛、血尿)的发生率估计为18.43%,Clavien III - IV级并发症(血肿、败血症)的发生率为2.48%。RIRS后最常见的并发症是发热或尿路感染,发生率为0.2 - 15%(尿脓毒症病例为0.1 - 4.3%)。PCNL后的并发症更常见,可能包括中度事件(需要输血的出血2 - 7%、尿脓毒症1 - 2%、肠道损伤<1%)以及严重事件(动静脉瘘0.5 - 1%、胸腔并发症<1%、通路丧失1 - 3%、死亡<0.5%)。接受抗血栓治疗的患者出血并发症风险显著增加。个性化的多学科方法能够在泌尿外科结石干预期间,在平衡抗血栓治疗与手术安全性方面做出最佳决策。最后,必须考虑到腔内泌尿外科手术可能因接触电离辐射而对手术医生及其团队造成伤害。因此,手术必须严格按照安全指南和规定进行,以尽量减少辐射暴露。在任何手术干预中,安全都是至关重要的,其次是疗效。然而,成本效益也应予以考虑。腔内泌尿外科手术成本高昂,主要是因为使用了复杂的设备,由于技术的持续快速发展,这些设备需要频繁更新。使用一次性设备有诸多好处,但也会导致成本进一步增加。最后,在成本效益评估中,必须考虑与某些类型手术相关的再次干预率。
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