title: Vitamin D insufficiency does not affect response of bone mineral density to alendronate.
abstract: CONCLUSIONS
  We investigated whether osteoporosis therapy with alendronate in postmenopausal patients is equally effective in patients who are vitamin D insufficient as in those who are vitamin D sufficient. We found that vitamin D insufficiency is common among patients with low bone density but that vitamin D insufficiency did not impair response to alendronate.
  
  
  BACKGROUND
  Treatment of vitamin D deficiency leads to significant improvements in bone mineral density (BMD); however, whether insufficiency affects BMD's response to bisphosphonate therapy is unknown.
  
  
  METHODS
  To determine whether vitamin D insufficiency at initiation of alendronate therapy for low BMD affects treatment efficacy, we used data from 1,000 postmenopausal women randomly selected from the vertebral fracture arm (n = 2,027) of the placebo-controlled Fracture Intervention Trial of alendronate. Participants were randomly assigned to placebo (50%) or alendronate therapy and most (83%) to calcium (500 mg/day) and cholecalciferol (250 IU/day). We measured serum 25-hydroxy vitamin D (25OHD) at enrollment, then categorized baseline vitamin D status according to 25OHD concentration (<or= 10 ng/ml = deficient; >10 but <or= 30 ng/ml = insufficient; >30 ng/ml = sufficient) and used linear regression to compare the effects of alendronate treatment among these categories.
  
  
  CONCLUSIONS
  At baseline, participants were vitamin D sufficient (14%), insufficient (83%), and deficient (2%). We found that BMD response to therapy at total hip or spine did not vary by vitamin D status at baseline (p for heterogeneity = 0.6). We determined that vitamin D insufficiency is common among participants with low BMD. However, vitamin D status at initiation of therapy does not affect BMD's response to alendronate, when it is coadministered with cholecalciferol and calcium.
authors.affiliation: Department of Medicine, San Francisco Department of Veterans Affairs Medical Center, University of California, San Francisco, CA 94121, USA. dantoniucci@psg.ucsf.edu
authors.forename: D M
authors.initials: DM
authors.lastname: Antoniucci
authors.forename: E
authors.initials: E
authors.lastname: Vittinghoff
authors.forename: L
authors.initials: L
authors.lastname: Palermo
authors.forename: D M
authors.initials: DM
authors.lastname: Black
authors.forename: D E
authors.initials: DE
authors.lastname: Sellmeyer
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D019386:Alendronate / Q000494:pharmacology*; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002762:Cholecalciferol / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy*; D013131:Spine / Q000000981:diagnostic imaging; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000150:complications*
chemical_list: D050071:Bone Density Conservation Agents; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D002118:Calcium; D019386:Alendronate