ROLE OF AGGLOMERATION IN THE EARLY STAGES OF PAPILLAR STONE FORMATION

Possible effects of crystal agglomeration on the early stages of calci um oxalate papillar stone formation are evaluated. The collecting duct s are filled with liquid that flows laminarly as established through h ydrodynamical and physicochemical considerations. Under such condition s, agglomeration due to laminar shear forces proceeds. Agglomeration o f calcium oxalate monohydrate crystals present in urine at a concentra tion typical for clinically observed crystalluria cannot result in the formation of a particle sufficiently large enough to be retained in t he Bellini's duct and become a papillar stone nidus (nucleus). Formati on of such an aggregate during the passage time of urine through the d uct requires an unrealistically high concentration of crystals in urin e, one that exceeds the normal content of urinary oxalate by several o rders of magnitude. Aggregates obstructing the Bellini's duct as assum ed in the free particle theory cannot represent a major factor in ston e formation. This conclusion is corroborated by experimental results a nd other observations.