Urolithiasis in a patient ingesting pure silica: a scanning electron microscopy study.

A patient who repeatedly produced urinary calculi, had consumed about 3 g of cristobalite (SiO2) per day for many years. Investigations using scanning electron microscopy revealed minute particles containing silicon in the core of the stone as well as in urine sediment. A mechanism similar to that proposed for the effect of silicon-containing drugs against gastric ulcer, may play a role in this formation of silicon-containing urinary stones.