title: Vitamin D supplementation and strontium ranelate absorption in postmenopausal women with low bone mass.
abstract: BACKGROUND
  Strontium ranelate is used to treat osteoporosis. Calcium (Ca) and strontium (Sr) have common chemical features and are absorbed by the same pathways. Vitamin D has a main role in calcium intestinal absorption. The aim of this study was to investigate whether vitamin D status is a determinant of strontium ranelate absorption.
  
  
  METHODS
  Twenty-five patients with vitamin D deficiency (25(OH)D<50 nmol/l) and 25 with vitamin D sufficiency (25(OH)D>75 nmol/l) underwent a 4-h oral Sr overload test. Sr absorption was evaluated as the fraction of absorbed dose and the area under the curve. After the baseline overload test, the deficient patients were treated until reaching sufficient vitamin D levels (25(OH)D>75 nmol/l) and the test was repeated.
  
  
  RESULTS
  Changing vitamin D status from deficient to sufficient resulted in a significant increase in 1,25(OH)2D (24.97±4.64×34.62±9.14 pg/ml, P<0.001) and a reduction in parathyroid hormone (73.87±37.50×58.24±20.13 pg/ml, P=0.006). Nevertheless, no differences were found in the parameters used to evaluate Sr absorption between the vitamin D deficient and sufficient groups. In addition, vitamin D3 replacement in the deficient group did not result in enhanced Sr absorption.
  
  
  CONCLUSIONS
  Vitamin D status did not interfere with strontium ranelate absorption. Taking into account the benefits of adequate vitamin D status in osteoporotic patients, we strongly recommend the treatment of vitamin D deficiency. However, the data demonstrate that such treatment does not enhance strontium ranelate absorption in patients with mild deficiency.
authors.affiliation: Bone and Mineral Unit, Division of Endocrinology, Federal University of São Paulo, Rua Borges Lagoa, 800 Vila Clementino, São Paulo SP 04.038-001, Brazil.
authors.forename: Tatiane
authors.initials: T
authors.lastname: Vilaça
authors.forename: Marília Brasílio Rodrigues
authors.initials: MB
authors.lastname: Camargo
authors.forename: Olguita Ferreira
authors.initials: OF
authors.lastname: Rocha
authors.forename: Marise
authors.initials: M
authors.lastname: Lazaretti-Castro
mesh_terms: D000368:Aged; D019540:Area Under Curve; D050071:Bone Density Conservation Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002118:Calcium / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016022:Case-Control Studies; D002762:Cholecalciferol / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy*; D011446:Prospective Studies; D013876:Thiophenes / Q000493:pharmacokinetics*; D014807:Vitamin D / Q000031:analogs & derivatives; D014808:Vitamin D Deficiency / Q000188:drug therapy / Q000378:metabolism*; D014815:Vitamins / Q000627:therapeutic use
chemical_list: D050071:Bone Density Conservation Agents; D013876:Thiophenes; D014815:Vitamins; C081587:strontium ranelate; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D002118:Calcium