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.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: 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.
Written by:
Wang X, Krambeck AE, Williams JC Jr, Tang X, Rule AD, Zhao F, Bergstralh E, Haskic Z, Edeh S, Holmes DR 3rd, Hernandez LP, Lieske JC. Are you the author?
Division of Nephrology and Hypertension, Department of Medicine; Department of Urology; Indiana University School of Medicine, Indianapolis, Indiana; Division of Biomedical Statistics and Informatics; Department of Physiology and Biomedical Engineering; Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; Division of Nephrology and Hypertension, Department of Medicine, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.
Reference: Clin J Am Soc Nephrol. 2014 Aug 4. pii: CJN.01490214.
doi: 10.2215/CJN.01490214
PubMed Abstract
PMID: 25092598