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Abnormalities Associated With Vitamin D

(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