Corticosteroid-induced
osteoporosis (CIO) is a serious disorder that results in significant long-term morbidity. Increased
bone resorption is caused by decreased Ca absorption and increased urinary Ca excretion leading to secondary hyperparathyroidsim.
Calcium prophylaxis alone, when patients start
corticosteroids, is associated with rapid rates of spinal bone loss and offers only partial protection from
corticosteroid-induced spinal bone loss. Though
calcium supplementation may have some benefit, it clearly cannot completely prevent
corticosteroid-induced bone loss. At most, Ca
therapy should only be considered adjunctive
therapy in the treatment or prevention of
corticosteroid-induced bone loss and should be administered in combination with other treatments. Earlier work demonstrated increases in forearm bone mineral density (BMD) with the use of Ca and
vitamin D in patients with established CIO. However, caution should be taken when interpreting these results, since bone loss generally tapers or plateaus after the first 12 months of
corticosteroid treatment; as such, any
therapy might show benefit. In addition, bone density was only taken at the radius and not the spine where most of the bone loss takes place. Nonetheless, in recent trials of at least 2-year duration in which
calcium and
vitamin D therapy served as
placebos, the result indicated that bone mass was maintained at the spine and hip throughout treatment in patients who had used chronic
corticosteroids. In primary prevention trials, the amount of bone loss observed in the spine after
therapy with Ca and
vitamin D combinations is similar to that observed in other prevention studies in the Ca alone-treated control groups. Furthermore, Ca and
vitamin D therapy appears to be less effective than other agents in the prevention of
corticosteroid-induce bone loss. Although several studies do not report side effects that may be associated with Ca and
vitamin D therapy, the few that do frequently report
hypercalciuria. In the absence of other studies that support the use of Ca and
vitamin D in the prevention of CIO, the data are too limited to generally recommend them alone as a preventative
therapy. Activated
vitamin D may be of greater benefit.