title: Calcium malabsorption in elderly women with vertebral fractures: evidence for resistance to the action of vitamin D metabolites on the bowel.
abstract: Radio-calcium absorption, plasma 25-hydroxyvitamin D [25-(OH)D] and 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations were measured in 19 elderly women with, and 21 without, vertebral fractures, before and after treatment with 25-hydroxyvitamin D3 [25-(OH)D3], to establish whether malabsorption of calcium in elderly women with vertebral fractures has a cause different from that in elderly women without vertebral fractures. Malabsorption of calcium and low plasma 25-(OH)D and 1,25-(OH)2D concentrations were common in both groups of women but there was no significant difference in these variables between the two groups. After treatment with 40 micrograms of 25-(OH)D3 daily for 7 days, there was a significant increase in plasma 25-(OH)D and 1,25-(OH)2D in both groups of women, but radio-calcium absorption increased significantly only in the group without vertebral fractures. Elderly women with vertebral fractures have malabsorption of calcium which is resistant to the action of vitamin D metabolites at concentrations which correct calcium malabsorption in elderly women without vertebral fractures.
mesh_terms: D015652:25-Hydroxyvitamin D 2; D000368:Aged; D002112:Calcifediol / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D004872:Ergocalciferols / Q000031:analogs & derivatives / Q000097:blood; D005260:Female; D005598:Fractures, Spontaneous / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy / Q000378:metabolism*; D013124:Spinal Injuries / Q000378:metabolism*
chemical_list: D002132:Calcium Radioisotopes; D004872:Ergocalciferols; D015652:25-Hydroxyvitamin D 2; C003564:1,25-dihydroxyergocalciferol; D002112:Calcifediol; D002118:Calcium