Category: Basic Science: Stones

MP2-1 - Intrarenal calcifications – Prospective phenotypic characterization by endoscopic and histologic quantification

Thu, Sep 20
4:00 PM - 6:00 PM

Introduction & Objective : Two papillary pathologies have been described that appear to be precursors of kidney stone growth: interstitial Randall's plaques and duct of Bellini plugs. Both appear to be composed of calcium phosphate. The underlying pathogenesis of either lesion is incompletely understood. In the current study we analyzed data from a large cohort of patients with diverse stone phenotypes and complete papillary mapping data in order to determine the relationship of papillary pathology to patient demographics, stone type and urinary chemistries.


Methods : A total of 295 patients undergoing percutaneous nephrolithotomy (PCNL) were prospectively evaluated with preoperative and postoperative dual energy CT, intraoperative endoscopic mapping and papillary biopsy as well as postoperative stone analysis, serum and 24-hour urine collection. Each papilla was mapped following stone removal with percent papillary plaque and plug coverage digitally measured using image analysis software and a representative papillary tip was biopsied. Stone composition was determined by micro-computed tomography and infrared analysis. A 24-hour urine collection was used to measure supersaturation (SS) and crystal growth inhibition.


Results : Across the cohort, 24-hour apatite and brushite SS significantly correlated with the amount of papillary plug (p1% plug surface area. Plaque was common throughout the group with 94% of stone formers having plaque on at least 1 papilla. Intraluminal crystals were present in 100%, 83%, 77%, in brushite, calcium oxalate and HA stone formers, respectively. Interestingly, within the entire cohort there were no differences between stone groups regarding any 24-hour urinary parameters except urinary oxalate (p< 0.01) and pH (p


Conclusions :

These data suggest that urinary SS predicts intratubular crystallization. Plaque formation may be more complicated and calcium excretion appears important.

Deepak K. Agarwal

Resident Physician
Mayo Clinic (Rochester)
Rochester, Minnesota

Felicity T. Enders

Mayo Clinic (Rochester)
Rochester, Minnesota

Ramila A. Mehta

Mayo Clinic (Rochester)
Rochester, Minnesota

Lisa E. Vaughan

Mayo Clinic (Rochester)
Rochester, Minnesota

Terri J. Vrtiska

Mayo Clinic (Rochester)
Rochester, Minnesota

Loren P. Herrera Hernandez

Mayo Clinic (Rochester)
Rochester, Minnesota

David R. Holmes

Mayo Clinic (Rochester)
Rochester, Minnesota

Andrew D. Rule

Mayo Clinic (Rochester)
Rochester, Minnesota

John C. Lieske

Mayo Clinic (Rochester)
Rochester, Minnesota

Amy E. Krambeck

Professor
Indiana University School of Medicine
Indianapolis, Indiana

Marcelino E. Rivera

Assistant Professor
Mayo Clinic (Rochester)
Rochester, Minnesota