Vitamin D and calcium supplementation accelerates Randall's plaque formation in a murine model.

Most of kidney stones are made of calcium oxalate crystals. Randall's plaque, an apatite deposit at the tip of the renal papilla is considered to be at the origin of these stones. Hypercalciuria may promote Randall's plaque formation and growth. We analyzed whether long-term exposure of Abcc6 mice (a murine model of Randall's plaque) to vitamin D supplementation, with or without calcium-rich diet, would accelerate the formation of Randall's plaque. Eight groups of mice (including Abcc6 and wild-type) received vitamin D alone (100,000 UI/Kg every 2 weeks), a calcium-enriched diet alone (calcium gluconate 2g/l in drinking water), both vitamin D supplementation and calcium rich diet, or a standard diet (controls) for 6 months. Kidney calcifications were assessed by 3D-micro-computed tomography, μ-Fourier transform infrared spectroscopy, field emission-scanning electron microscopy, transmission electron microscopy, and Yasue staining. At 6 months, Abcc6 mice exposed to vitamin D and calcium supplementation developed massive Randall's plaque when compared to control Abcc6 mice (P < 0.01). Wild-type animals did not develop significant calcifications when exposed to vitamin D. Combined administration of vitamin D and calcium accelerates significantly Randall's plaque formation in a murine model. This original model raises concerns about the cumulative risk of vitamin D supplementation and calcium intakes in Randall's plaque formation.