Distinguishing Characteristics of Idiopathic Calcium Oxalate Kidney Stone Formers with Low Amounts of Randall's Plaque

Background Overgrowth of calcium oxalate on Randall9s 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 Randall9s plaque coverage was analyzed and used to divide ICSFs into those with a high (≥5%; mean, 10.5%; n =10) versus low ( 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 Conclusions These findings suggest that other pathways independent of Randall9s plaque may contribute to stone pathogenesis among a subgroup of ICSFs who harbor low amounts of plaque.