Investigations on flow dynamics and microstructure and their contribution to urolith genesis.

Stones originating in the tubular system may grow in the renal calyces without being excreted. From the analysis of flow dynamics nearly steady turbulences with long retention times should be expected, in which particles with a density of about 1.0 can grow. By this, hydrodynamics would support the matrix theory of stone genesis. Microscopic structures of the central stone regions also support 'organic early stages in urolith genesis.'

[Microscopic investigation of the partial stages of dissolution processes in urinary calculi (author's transl)]. / Mikroskopische Untersuchung der Teilschritte von Auflösungsvorgängen an Harnsteinen

The formation of urinary calculi cannot yet be prevented with certainty. Consequently the dissolution of stones remains a focus of medical interest. The speed of solution of a calculus is not a quantity typical of the substance, but depends largely on the structural formation of the urinary calculi. With very different types of structure (e.g. Whewellite and Weddellite stones) the rate of dissolution can therefore fluctuate between wide limits in spite of similar phase composition. Consequently, type of structure, course of solution and rate of solution can be clearly correlated. Stones with relatively uniform structure formation (e.g. Struvite stones) on the other hand show largely similar solution rates. Medically, it is of interest that in certain structural types, solution may lead to disintegration of the stone into isolated solution residues.