**4. CKD – MBD – and vascular calcification**

Tissue calcification is a complex and highly regulated process in bone and teeth, and also at extraosseous sites. The most threatening localization of unwanted calcification is at vascular sites, where it may manifest as both medial and intimal calcification of arteries. Studies in the general population have identified calcification in most of atherosclerotic plaques. Calcification seems to be a part of the natural development of atherosclerotic plaques, with extensive calcification associated with late-stage atherosclerosis. In the general population, atherosclerotic plaque calcification is associated with cardiovascular events such as myocardial infarction, symptomatic angina pectoris, and stroke. Medial calcification causes arterial stiffness, resulting in an elevated pulse pressure and increased pulse wave velocity, thereby contributing to left ventricular hypertrophy, dysfunction, and heart failure. Furthermore, an advanced calcification of the heart valves may lead to dysfunction contributing to heart failure and a risk of endocarditis development (Vliegenthart et al. 2002; Vliegenthart et al. 2002).
