RT Journal
A1 Gallieni M
T1 HIgh-dose oral vitamin d supplementation and risk of falls in older women
JF JAMA
JO JAMA
YR 2010
FD August 25
VO 304
IS 8
SP 854
OP 857
DO 10.1001/jama.2010.1167
UL http://dx.doi.org/10.1001/jama.2010.1167
AB 
To the Editor: In their randomized controlled trial, Dr Sanders and colleagues1 hypothesized that an annual high-dose oral cholecalciferol administration would reduce the risk of fractures based on previous results in randomized and observational studies but found an increased risk. Other studies, including a Cochrane review,2 had yielded negative results. The mechanisms underlying increased fracture risk from bolus vitamin D supplementation are uncertain. The effects of treatment on 25-hydroxycholecalciferol 24-hydroxylase and 1-alpha-hydroxylase, renal and extrarenal, could be better interpreted if levels of 1,25-dihydroxycholecalciferol (1,25(OH)2D) were determined in the substudy participants who underwent 25-hydroxycholecalciferol serum level assessment. The relative grade of activity of the 2 enzymes could determine increased, unchanged, or diminished serum levels of 1,25(OH)2D.