Brushite Stones: A Registry and Database of Clinical and Laboratory Findings

Multiple treatment options are available for the treatment of kidney or ureteral calculi. Treatment options include shock wave lithotripsy (SWL; shock waves are transmitted through the body wall and focused onto the stone to break the stone into gravel), percutaneous nephrolithotomy (PNL; a small flank incision is made and a telescope inserted into the kidney to allow stone fragmentation and removal from the patient), and ureteroscopic lithotripsy (URS; a small telescope is inserted into the ureter or kidney and a laser is used to break up the stone into gravel). Brushite is a unique form of calcium phosphate kidney stone that often has sub-optimal stone fragmentation with shock wave lithotripsy (Heimbach et al, 1999). Due to its SWL resistance, brushite patients often undergo more invasive treatments such as URS or PNL to achieve a stone free status. Brushite patients often have multiple stones and have a high likelihood of developing recurrences (new stone formation or regrowth of existing stone fragments), often within the first year after surgery. These patients may also have a history of anatomical abnormalities of the urinary tract or a history of prior renal or ureteral surgery (Klee et al, 1991). A thorough review of the clinical, radiological and metabolic data of brushite patients has the potential to clarify a number of important points. Many patients with brushite stones often have a history of non-brushite stones (e.g. calcium oxalate) predating the development of brushite stones and historical review is needed to define the factors contributing to this shift in stone composition. In addition, it has been shown that CT attenuation values can be used to predict stone composition (Joseph et al, 2002). As a result, it is crucial to review the radiologic appearance of known brushite stones to identify specific radiographic characteristics and possibly allow a radiographic diagnosis of brushite to be established. Finally, very little information has been reported on the urinary abnormalities in brushite patients. By carefully examining 24 hour urine data in a large population of brushite patients, information may be identified that can be used to provide improved management of specific abnormalities to prevent stone recurrences.