title: Distinguishing characteristics of idiopathic calcium oxalate kidney stone formers with low amounts of Randall's plaque.
abstract: BACKGROUND
  Overgrowth of calcium oxalate on Randall's plaque is a mechanism of stone formation among idiopathic calcium oxalate stone-formers (ICSFs). It is less clear how stones form when there is little or no plaque.
  
  
  METHODS
  Participants were a consecutive cohort of ICSFs who underwent percutaneous nephroscopic papillary mapping in the kidney or kidneys containing symptomatic stones and a papillary tip biopsy from a representative calyx during a stone removal procedure between 2009 and 2013. The distribution of Randall's plaque coverage was analyzed and used to divide ICSFs into those with a high (≥5%; mean, 10.5%; n=10) versus low (<5%; mean, 1.5%; n=32) amount of plaque coverage per papilla. Demographic and laboratory features were compared between these two groups.
  
  
  RESULTS
  Low-plaque stone formers tended to be obese (50% versus 10%; P=0.03) and have a history of urinary tract infection (34% versus 0%; P=0.04). They were less likely to have multiple prior stone events (22% versus 80%; P=0.002) and had a lower mean 24-hour urine calcium excretion (187±86 mg versus 291±99 mg; P<0.01). Morphologically, stones from patients with low amounts of plaque lacked a calcium phosphate core by microcomputed tomography. Papillary biopsies from low plaque stone-formers revealed less interstitial and basement membrane punctate crystallization.
  
  
  CONCLUSIONS
  These findings suggest that other pathways independent of Randall's plaque may contribute to stone pathogenesis among a subgroup of ICSFs who harbor low amounts of plaque.
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine.
authors.forename: Xiangling
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Urology.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Krambeck
authors.affiliation: Indiana University School of Medicine, Indianapolis, Indiana.
authors.forename: James C
authors.initials: JC
authors.lastname: Williams
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Tang
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rule
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Division of Biomedical Statistics and Informatics.
authors.forename: Eric
authors.initials: E
authors.lastname: Bergstralh
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine.
authors.forename: Zejfa
authors.initials: Z
authors.lastname: Haskic
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine.
authors.forename: Samuel
authors.initials: S
authors.lastname: Edeh
authors.affiliation: Department of Physiology and Biomedical Engineering, and.
authors.forename: David R
authors.initials: DR
authors.lastname: Holmes
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Loren P
authors.initials: LP
authors.lastname: Herrera Hernandez
authors.affiliation: Division of Nephrology and Hypertension, Department of Medicine, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; and Lieske.John@mayo.edu.
authors.forename: John C
authors.initials: JC
authors.lastname: Lieske
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000032:analysis / Q000652:urine; D001706:Biopsy; D002129:Calcium Oxalate / Q000032:analysis*; D002130:Calcium Phosphates / Q000032:analysis; D003430:Cross-Sectional Studies; D003460:Crystallization; D004724:Endoscopy; D005260:Female; D006801:Humans; D007668:Kidney / Q000737:chemistry* / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D007669:Kidney Calculi / Q000737:chemistry* / Q000175:diagnosis / Q000209:etiology / Q000601:surgery / Q000652:urine; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D011237:Predictive Value of Tests; D011446:Prospective Studies; D065667:Renal Elimination; D012307:Risk Factors; D016482:Urinalysis; D014552:Urinary Tract Infections / Q000150:complications; D055114:X-Ray Microtomography
chemical_list: D015415:Biomarkers; D002130:Calcium Phosphates; D002129:Calcium Oxalate; C020243:calcium phosphate
keywords: hypercalciuria; kidney stones; obesity
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