Login to Access Video or Poster Abstract: MP19-12
Sources of Funding: NIH P01 DK056788

Introduction

Mechanisms of early stone retention within the kidney are understudied and poorly understood. To date, attachment via Randall's plaque is the only widely accepted theory in this regard, best described in some idiopathic calcium oxalate stone formers. Brushite stone formers are known to have distinct papillary morphology relative to idiopathic calcium oxalate stone formers. As such, we sought to determine whether stone attachment mechanisms in such patients may be similarly unique.

Methods

Patients undergoing percutaneous and or ureteroscopic procedures for stone removal were consented for endoscopic renal papillary examination and individual stone collection. Each removed stone was processed using micro computed tomographic imaging in order to assess three dimensional microstructure and search for recurring structural features indicative of novel mechanisms of early growth and attachment to renal tissue._x000D_

Results

Twenty eight unbroken brushite stones were removed and analyzed from nine patients. Video confirmation of attachment was available for 13/28 stones (46%) with the remainder believed to have recently dislodged naturally or in response to manipulation during the procedure. 3D assessment failed to show evidence of Randall's plaque associated with any stone. Conversely, each brushite stone demonstrated microstructural evidence of having grown attached to a ductal plug formed of apatite.

Conclusions

Three dimensional analysis of small brushite stones suggests overgrowth on ductal apatite plugs as a mechanism of early stone growth and retention. Such findings represent initial supporting evidence for a novel mechanism of stone formation that has previously been hypothesized but never verified.

Funding

NIH P01 DK056788