Trimagnesium orthophosphate in renal calculi.

We recently described a new component of calculi, trimagnesium orthophosphate. In a microscopical study of thin sections from 3500 urinary calculi we detected this compound in 14 stones, all of which contained struvite. New data suggest that trimagnesium orthophosphate is a transformation product of struvite. This well-crystallized substance was always detected a few days after the surgical extraction of struvite kidney stones, in contrast to the newberyite that appears on the surface of very old removed stones or after long exposure of stones to the atmosphere.