Bone mass in patients with renal diseases

Severe distortion of of calcium metabolism is implied in a variety of renal diseases, of which only an incomplete overview may be offered. In consequence of the renal loss of rapidly available intravasal and intracellular calcium, a creeping loss of bone-bound calcium is occuring. The skeleton may not falsely be understood as a calcium reservoir rather than having to maintain mechanical tasks. Consecutively, the loss of bone material (mineral) leads to an immediate repair response due to the mechanostat principle, resulting in a counter-regulatoring action to preserve mechanical competence. However, due to the humoral imbalance, only mechanically incompetent bone can be formed, in accordance to the known histologically classified findings. One major and measurable characteristic of this bone material is the lack of calciumhydroxyapatite. This has to be assessed in time by bone densitometry, in order to be able to start preventive measures. The examples presented here demonstrate the impact of some nephrological diseases on bone mineral density as well as the therapeutic consequences thereof. (orig.)