The role of vitamin D in vascular calcification in chronic kidney disease.

Vascular calcification is a significant cause of morbidity and mortality in patients with chronic kidney disease (CKD). Disorders of mineral metabolism are likely involved in the pathogenesis of vascular calcification. Calcitriol and its analogs are effective in suppressing parathyroid hormone levels in patients with secondary hyperparathyroidism and CKD, but experimental studies demonstrate that these drugs can act directly on vascular smooth muscle cells. In some in vitro studies and in animal models of CKD, calcitriol has induced vascular calcification. Newer analogs of vitamin D appear to be less likely to induce vascular calcification, although published data are scarce. However, there is really no clear evidence in dialysis patients that calcitriol or analog administration is directly responsible for the induction of vascular calcification. However, indirectly, by oversuppression of parathyroid hormone (PTH) and induction of a low-turnover bone disease state, or by increased calcium-phosphorus product, the administration of calcitriol or its analogs may contribute to vascular calcification in patients with CKD. However, prospective randomized trials in CKD patients are necessary to fully understand the impact of calcitriol and analog therapy on vascular calcification.