Vitamin D and bone mineral density changes in postmenopausal women treated with strontium ranelate.

OBJECTIVE: Vitamin D deficiency is widespread and often reported in subjects treated for osteoporosis. Optimal vitamin D repletion was previously shown to maximize the efficacy of anti-resorptive agents. To date, no information exists about the role of vitamin D in the response to strontium ranelate (SrR) treatment. The aim of our study was to investigate the BMD response to SrR in accordance with change of vitamin D status. METHODS: A retrospective analysis of 108 women receiving SrR for postmenopausal osteoporosis was carried out. Women were treated with SrR (2 g/day), with cholecalciferol (25,000 IU biweekly) and calcium carbonate as appropriate. Lumbar spine and femoral neck BMD, bone formation markers (BGP, ALP), resorption marker (OH-PRO) and serum 25(OH)D were measured at baseline after 18-months. All participants were divided into two groups according to the median variation of 25(OH)D over the observation period. RESULTS: SrR was associated with improvement of BMD at lumbar spine (p < 0.0001) and to a non significant variation at femoral neck (p = 0.2). Only subjects with Δ25(OH)D > 6.14 %, reported a significant BMD gain at femoral neck (p = 0.03). Change of BMD at femoral neck was positively associated with modification of ALP (r = 0.28, p = 0.01). This association was not maintained when considering only women with Δ25(OH)D < 6.14 % (r = 0.28, p = 0.09). At a multiple regression analysis, ALP change was the only predictor of femoral neck BMD modification (ß 0.13; SE 0.05; p = 0.01). CONCLUSION: Improvement of vitamin D status was associated with enhancement of BMD response to SrR in women with postmenopausal osteoporosis, in particular, at femoral neck.