Vascular calcification.

Vascular calcification is an active and modifiable process involved in many disease entities, including atherosclerosis, cardiac valve disease and calcific uremic arteriolopathy. It occurs with distinct characteristics at different sites in the vessel wall. The mechanism by which calcification is induced remains uncertain; the roles of bone matrix and extracellular matrix proteins, estrogen and vitamin D are being further defined in animal models and clinical trials. Some risk factors for calcific uremic arteriolopathy and cardiac valve calcification, both disproportionately affecting chronic hemodialysis patients, have been identified in observational studies.