Pathogenesis of renal stones.

The process of stone formation within the urinary tract involves multiple etiologic factors. Metabolic and/or ion transport abnormalities, either primary or secondary, provide relative solute excess. Multiple changes in the physical chemistry of the urine follow, leading to crystal formation and the potential for stones to occur. The states of saturation, sites and mechanism of crystal retention, and modifiers of crystal formation influence directly this process. In the evaluation of a patient with stones, etiologic factors, be they in the areas of metabolism, ion transport or physical chemistry should be identified. Treatment is then designed to correct these specific abnormalities. The remainder of this article will be devoted to considerations of these principles.