Demographics and characterization of 10,282 Randall’s plaque-related kidney stones: a new epidemic?

Renal stone incidence has progressively increased in industrialized countries but the implication of Randall’s plaque in this epidemic remains unknown. Our objectives were to determine whether Randall’s plaque-related stones prevalence increased during the past decades after having analyzed 30,149 intact stones containing mainly calcium oxalate since 1989 (cross-sectional study), and to identify determinants associated with Randall’s plaque-related stones in patients (case-control study). The proportion of Randall’s plaque-related stones was assessed over three time periods: 1989-1991, 1999-2001 and 2009-2011. Moreover, we analyzed clinical and biochemical parameters of 105 patients affected by calcium oxalate stones, with or without plaque. Of 30,149 calcium oxalate stones, 10,282 harboured Randall’s plaque residues (34.1%). The prevalence of Randall’s plaque-related stones increased dramatically during the past years. In young females, 17% of calcium oxalate stones were associated with Randall’s plaque during the 1989-1991 period but the proportion rose to 59% twenty years later (p <0.001). Patients with plaques experienced their first stone-related event earlier in life as compared to those without plaque (median age: 26 vs 34 years, p=0.02), had increased ionized serum calcium levels (p=0.04), increased serum osteocalcin (p=0.001) but similar 25(OH) vitamin D levels. The logistic regression analysis showed that age (OR 0.96, CI [0.926-0.994], p=0.02), weight (OR 0.97, CI [0.934-0.997], p=0.03), and osteocalcin serum levels (OR 1.12, CI [1.020-1.234], p=0.02) were independently associated with Randall’s plaque. The prevalence of the FokI f vitamin D receptor polymorphism was higher in patients with plaque (p=0.047). In conclusion, these findings point to an epidemic of Randall’s plaque-associated renal stones in young patients and suggest a possible implication of altered vitamin D response.