我們發表兩位以體外震波碎石治療之病人。其結石被擊碎並於一個月內排出。紅外線分光儀証實為Aragonite，屬於碳酸鈣之變異體。其中一位患有痛風及便秘，服用含鎂之軟便劑多年。另位則未服用任何特別藥物。兩者都有尿鎂，尿鈣過高及鹼性尿。其它生化檢驗包括血清鈣，磷及尿酸都正常。據了解，Aragonite非常不穩定而鎂離子能穩定及阻止其轉變為較穩定之菱形晶體，Calcite。

We present two cases of urinary calculi treated with extracorporeal shock wave lithotripsy. The stones were disintegrated and passed out within one month. Infrared spectrometer demonstrated aragonite, a variety of calcium carbonate. One patient sufferred from gout and constipation and had been taking magnesium containing laxative for several years. Another patient never took any special drug. Hypermagnesiuria (108 & 111mg/24 hrs), hypercalciuria (250 mg/24 hrs) and alkaline urine were noted in these two patients. The other urine biochemistry including calcium, phosphate and uric acid were within normal range. To the best of our knowledge, the stone constituent, aragonite, was very unstable and magnesium cation may stabilize and stop it inverting to calcite, the stable rhombohedral form of calcium carbonate.