The prevalence of vitamin D inadequacy amongst women with osteoporosis: an international epidemiological investigation
Speaking of wreaking havoc, in this study a whopping 64% of the women with osteoporosis were Vit D deficient. I can honestly say that I have never had a patient come into my office on any type of anti-resporptive agents (like Fosomax or Actonel) that was told to take Vit D. Most, but not all, are told to take calcium.
Given that Vit D at 2-4000 IU per day is practically free (and sunlight is free), the safety of taking 10,000 IU daily is well accepted and that Vit D has such a broad range of positive effects, there is absolutely no reason not to recommend this to everyone with osteoporosis.