title: Local action of oral 1,25-dihydroxycholecalciferol on calcium absorption in osteoporosis.
abstract: To investigate whether low calcium absorption in osteoporosis improves by increasing 1,25-dihydroxyvitamin D both systemically in plasma and locally in gut, the effects of oral 25-hydroxycholecalciferol and oral 1,25-dihydroxycholecalciferol on plasma 1,25-dihydroxy-vitamin D (1,25-(OH)2D) and calcium absorption were studied in 20 postmenopausal patients with vertebral osteoporosis. In 10 patients taking oral 0.25 micrograms 1,25-dihydroxycholecalciferol twice daily for 7 d, calcium absorption increased more than in 10 patients taking oral 40 micrograms 25-hydroxycholecalciferol once daily for 7 d (p less than 0.02) despite both groups having a similar increase in plasma 1,25-(OH)2D. These results support the view that the major effects of oral 1,25-dihydroxycholecalciferol on absorption is due to a local action on the gut and that it is possible to increase calcium absorption in osteoporosis with oral 1,25-dihydroxycholecalciferol without increasing its undesirable action on bone resorption.
mesh_terms: D000284:Administration, Oral; D000368:Aged; D000369:Aged, 80 and over; D002112:Calcifediol / Q000627:therapeutic use; D002117:Calcitriol / Q000008:administration & dosage / Q000627:therapeutic use*; D002118:Calcium / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000097:blood; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy* / Q000378:metabolism; D013122:Spinal Diseases / Q000188:drug therapy* / Q000378:metabolism
chemical_list: D004100:Dihydroxycholecalciferols; D002117:Calcitriol; D002112:Calcifediol; D002118:Calcium