Vitamin D insufficiency does not affect bone mineral density response to raloxifene.
BACKGROUND
Vitamin D insufficiency and osteoporosis are common and often coexist in postmenopausal women.


OBJECTIVE
The objective of this study was to test whether the presence of vitamin D insufficiency at the initiation of raloxifene therapy affected the subsequent response of bone mineral density (BMD).


METHODS
We studied 7522 postmenopausal participants of the Multiple Outcomes of Raloxifene Evaluation, a placebo-controlled trial of the effects of raloxifene on BMD and fracture.


METHODS
After enrollment, all participants began daily supplements of 500 mg calcium and 400-600 IU cholecalciferol; 1 month later, women were randomly assigned to placebo or raloxifene.


METHODS
Serum levels of vitamin D [25-hydroxy vitamin D (25OHD)] were measured at enrollment, randomization, and 6 months later. We categorized participants' vitamin D status (deficient, insufficient, or sufficient) based on their randomization 25OHD level. We estimated the effects of treatment on BMD within these subgroups using linear regression models.


RESULTS
At enrollment, 3.2% of participants were vitamin D deficient, and 51.8% were insufficient; after 7 months of cholecalciferol supplementation, 0.2% of all participants remained D deficient, and 23.6% remained insufficient. The effects of raloxifene on hip and spine BMD did not vary by vitamin D status at randomization (P = 0.08 and P = 0.7, respectively).


CONCLUSIONS
We conclude that vitamin D status at initiation of raloxifene therapy does not affect the subsequent BMD response when coadministered with cholecalciferol and calcium. After 7 months of cholecalciferol therapy, very few women continued to have 25OHD levels in the deficient range; however, 25OHD levels remained suboptimal in nearly one fourth of the cohort. Additional research is needed to determine whether these observations can be generalized to other antiresorptive agents.
Antoniucci
Diana M
DM
Division of Endocrinology, Department of Medicine, University of California, San Francisco, California 94143, USA. dantoniucci@psg.ucsf.edu
Vittinghoff
Eric
E
Blackwell
Terri
T
Black
Dennis M
DM
Sellmeyer
Deborah E
DE
D000368:Aged; D015519:Bone Density / Q000187:drug effects*; D004347:Drug Interactions; D004965:Estrogen Antagonists / Q000008:administration & dosage*; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D010024:Osteoporosis / Q000188:drug therapy* / Q000453:epidemiology; D017698:Postmenopause; D020849:Raloxifene Hydrochloride / Q000008:administration & dosage*; D016103:Spinal Fractures / Q000453:epidemiology / Q000517:prevention & control; D014807:Vitamin D / Q000008:administration & dosage; D014808:Vitamin D Deficiency / Q000150:complications*
D004965:Estrogen Antagonists; D014807:Vitamin D; D020849:Raloxifene Hydrochloride