Crystallization in urine.

Abstract

Urines are normally supersaturated with respect to calcium oxalates and phosphates. The formation of these phases in simulated in vitro experiments may give an indication of the likelihood of stone formation in vivo. However, spontaneous precipitation and normal seeded growth experiments suffer from the disadvantage that only small extents of reaction can be achieved. In the present work, a constant composition method has been used to investigate the nature of the phases which crystallize and the rates of their formation in urines. The large extents of crystallization at sustained supersaturation enables physical chemical characterization of the phases formed. Moreover, the use of a protected calcium electrode has made possible the kinetic studies in the presence of undiluted urines. Depending upon the relative supersaturations, and presence of natural inhibitors, both calcium oxalate and calcium phosphate phases may be formed following the addition of calcium oxalate seed crystals.