Bone Abstracts

Introduction: The purpose of this study was to evaluate whether daily treatment with 400 IU vitamin D₃ was sufficient to maintain 25-hydroxyvitamin D (25(OH)D) concentrations above 60 nmol/l over a 3-year period. In addition, the study aimed to clarify if any differences existed in serum 25(OH)D between pre-supplemented women and women who already had serum 25(OH)D above 60 nmol/l at screening.

Methods: Serum samples drawn from 251 postmenopausal osteoporotic women over a 3-year period were analyzed for 25(OH)D, parathyroid hormone (PTH), and phosphate. Furthermore, a comprehensive patient file review was performed to collect patient characteristics and laboratory results. RM-ANOVA was applied to evaluate treatment effect over time. Approval was obtained from The Danish Scientific Ethical Committee, Region North Jutland, Denmark (N-20120060).

Results: Serum 25(OH)D increased significantly over the 3-year period (P>0.001). The mean increase was 24 nmol/l. Pre-supplemented women had a significantly lower mean 25(OH)D concentration compared to non-pre-supplemented women (P<0.001) but remained above 60 nmol/l. Season significantly interacted with 25(OH)D concentrations (P<0.001) and concentrations measured during winter were significantly elevated compared to other seasons (P<0.05).

Conclusions: It appears that daily treatment with 400 IU vitamin D₃ over a 3-year period is sufficient to maintain serum 25(OH)D above 60 nmol/l.