[Calcium oxalate monohydrate (whewellite) renal lithiasis]

Pure calcium oxalate monohydrate lithiasis is rare--about 5 to 10% of total renal lithiases. The proportion is the same in men and women. Pure calcium oxalate stones are a polished dark brown color, and are very hard. They are visualized radiologically as regular and homogeneous. From a biological standpoint, this type of stone is frequently associated with normal calciuria and oxaluria. Pure calcium oxalate monohydrate stones rarely evolve.