(see also: Vit D Discussion, Calcitriol/Rocalrol/Calcifediol)
Discussion
- primary function of l,25-Vitamin D3 is to maintain skeletal homeostasis as well as for maintenance of plasma Ca homeostasis;
- primary effect of lack of Vit D is decrease in miceralization of newly formed bone matrix (osteoid);
- rate of bone formation is decreased;
- net result is less total bone & marked change in quality of bone;
- only minute amounts of vitamin D are necessary for parathyroid hormone to carry out its actions on bone and kidney;
- osteomalacia, group of dz, characterized by defective mineralizaiton can be caused by any problem resulting in inadequate amounts of Vit D or low PO4;
- in osteomalacia defective mineralizaiton results in relative increase in amount of osteoid (unmineralized bone matrix) in bone;
Vitamin D Discussion
- persons who do not receive adequate daily sunlight exposure, such as those confined to home or nursing facility, may be at special risk for vitamin D deficiency;
- decrease in mineralization of newly formed bone matrix (osteoid);
- rate of bone formation is decreased;
- net result is less total bone & marked change in quality of bone;
- osteomalacia
- defective mineralization results in relative increase in amount of osteoid (unmineralized bone matrix) in bone;
- in skeletally immature individuals, mineralization in growth plates is also affected;
- osteomalacia in this setting is called rickets (Vitamain D Deficient Rickets)
- impaired mineralization of cartilage in the zone of calcification arrests enchondral ossification & prevents formation of the primary spongiosa;
- Vitamin D Resistant Rickets