Ultrafine Structure of the Hydroxyapatite Amorphous Phase in Noninfectious Phosphate Renal Calculi

Based on the observed calculus structure, the following mechanism of formation of the noninfectious phosphate calculi is suggested: Spherulites formed via the perikinetic aggregation of Posner's clusters present in urine supersaturated with respect to hydroxyapatite aggregate into spherical agglomerates that, after reaching a certain size, are retained in cavities with poor urodynamics, gradually settle, and become incorporated into developing concretion. The columnar crystals are probably nucleated on the detritus of organic origin embedded in the hydroxyapatite structureless phase.