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Filter by:Urolithiasis is a common condition in the United States, and is associated with significant morbidity and even mortality. The most commonly occurring urinary calculi are comprised of calcium oxalate salts, and until recently, the pathogenesis of calcium oxalate calculi was poorly understood. New evidence, however, suggests that the development of calcium oxalate calculi may be intimately associated with hydroxyapatite (HA) plaque, also known as Randall's plaque, which is located on the renal papillae. The investigators have previously demonstrated that Randall's plaque originates in the thin ascending limb of the loop of Henle, and they have shown that Randall's plaque is composed of HA (Evan, Lingeman et al. 2003). As well, the amount of Randall's plaque correlates with elevated levels of urinary calcium and decreased urinary volume, risk factors for the formation of calcium oxalate calculi (Kuo, Lingeman et al. 2003). In the course of these previous studies, the investigators have anecdotally noted that calcium oxalate stones are often found attached to Randall's plaque, an observation that others have reported as well (Prien 1949; Carr 1954; Cifuentes Delatte, Minon-Cifuentes et al. 1987). However, there has been no in-vivo, rigorous documentation of this "attached stone" relationship. Attached calculi represent an important point in the pathogenesis of calcium oxalate calculi, as they correspond to a moment in time where there is a continuum between the HA plaque of Randall and the calcium oxalate stone, thus linking the origin of plaque with the development of stone. A better understanding of the phenomenon of attached calculi will lead to a better understanding of how and why calcium oxalate stones form, which may ultimately direct future interventions to attenuate stone activity.
Patients with large or otherwise complex renal calculi are commonly treated by percutaneous nephrolithotomy (PNL; PERC). PERC requires the creation of an approximately 10 mm channel through the renal parenchyma, into the intra-renal collecting system, in order to effect stone fragmentation and extraction. Although the nephrostomy tract is confined to a small fraction of the renal parenchyma (approximately 1%), the trauma associated with the creation of the tract will affect blood flow and oxygen delivery to regions beyond the immediate site of injury. It is possible that this could result in a significant functional renal impairment. There are several reports describing the effect of PERC on renal function, but interpretation of these studies is difficult, due to a lack of uniformity in patient selection and variability in the timing of peri-operative evaluation. Recent data from the investigators' lab, obtained from a porcine model, suggest that, acutely, PERC causes a significant decrease in renal function as measured by para amino hippurate (PAH) clearance. The purpose of this study is to determine, in a rigorous and standardized fashion, the acute effects of PERC on renal function, as measured by nuclear renography.
Historically, percutaneous treatment of stone-bearing caliceal diverticula has resulted in the best success rates when examining factors such as symptom relief and stone-free rates (Jones, et al, 1991). Many groups have reported modifications in their percutaneous approach which have reportedly improved patient outcomes, but these series have very limited populations. Another issue concerning stone-bearing caliceal diverticula centers on the etiology of stones formation within these areas. This topic remains a subject of debate, with conflicting data in the literature.