Mandhani Anil, Raghavendran Maniyur, Srivastava Aneesh, Kapoor Rakesh, Singh Uttam, Kumar Anant, Bhandari Mahendra
Department of Urology, Sanjay Ghandhi Post Graduate Institute of Medical Sciences, Lucknow, India.
J Urol. 2003 Oct;170(4 Pt 1):1097-100. doi: 10.1097/01.ju.0000086092.38214.24.
Stone fragility is a key factor for the success of shock wave lithotripsy (SWL). Dual x-ray absorptiometry is the gold standard for measuring bone mineral content and density, which helps in determining bone mass and the fracture risk. The same principle was applied to determine the relationship of stone mineral content (SMC) and density (SMD) to predict the fragility of stone before SWL.
A total of 102 patients with a solitary renal and upper ureteral stone of less than 3 cm treated at a single center with a lithotriptor were included. Prior to SWL all patients underwent dual x-ray absorptiometry evaluation for SMC and SMD. Plain x-ray documented disintegration after SWL. Stone size and site, the number of shock waves and energy levels were recorded. Failure was defined as no fragmentation to a size of less than 4 mm, which would pass unaided, up to a maximum of 3,000 shock waves.
Overall 94 patients with renal stones were included. Mean stone size was 16.68 +/- 7 mm (range 5 to 30). Mean and median SMC was 0.63 +/- 0.83 and 0.34 gm (range 0.01 to 5.54), and mean and median SMD was 0.48 +/- 0.19 and 0.46 gm/cm2 (range 0.05 to 1.12), respectively. Overall 67 patients (71%) had successful fragmentation and clearance at a mean of 1,623.58 +/- 658.77 shock waves (range 355 to 3,000). On logistic regression analysis only SMC was the significant factor affecting the outcome in terms of fragmentation. At a SMC of more than 1.27 gm 95% of the stones would not fragment or needed more than 3,000 shock waves.
Patients with high stone mineral content (SMC greater than 1.27 gm) could be directly offered percutaneous nephrolithotomy, thus, avoiding the unnecessary cost of prior SWL.
结石易碎性是冲击波碎石术（SWL）成功的关键因素。双能X线吸收法是测量骨矿物质含量和密度的金标准，有助于确定骨量和骨折风险。应用相同原理来确定结石矿物质含量（SMC）和密度（SMD）之间的关系，以预测SWL前结石的易碎性。
共纳入102例在单一中心接受碎石机治疗的孤立性肾及上段输尿管结石且结石直径小于3 cm的患者。在SWL之前，所有患者均接受双能X线吸收法评估以测定SMC和SMD。普通X线记录SWL后的结石崩解情况。记录结石大小和部位、冲击波次数和能量水平。失败定义为结石未碎至小于4 mm大小，且在最多3000次冲击波治疗后仍无法自行排出。
总共纳入94例肾结石患者。平均结石大小为16.68±7 mm（范围5至30 mm）。平均和中位数SMC分别为0.63±0.83 g和0.34 g（范围0.01至5.54 g），平均和中位数SMD分别为0.48±0.19 g/cm²和0.46 g/cm²（范围0.05至1.12 g/cm²）。总体而言，67例患者（71%）成功碎石并清除，平均冲击波次数为1623.58±658.77次（范围355至3000次）。逻辑回归分析显示，就结石碎裂而言，只有SMC是影响结果的显著因素。当SMC超过1.27 g时，95%的结石不会碎裂或需要超过3000次冲击波。
结石矿物质含量高（SMC大于1.27 g）的患者可直接接受经皮肾镜取石术，从而避免先前SWL的不必要费用。
