Effect of a vitamin D analog on leg bone mineral density in patients with chronic spinal cord injury

A randomized, placebo-controlled trial was performed to determine the effect of a vitamin D analog (1-alpha-hydroxyvitamin D₂ [1-alpha D₂]) on the bone mineral density (BMD) in patients with chronic spinal cord injury (SCI). Forty subjects with chronic complete motor SCI were enrolled. The mean plus or minus standard deviation age and duration of injury were 42 plus or minus 12 yr and 11 plus or minus 10 yr, respectively. Either 4 micrograms 1-alpha D₂ (n = 19) or placebo (n = 21) was administered daily for 24 mo. Metabolic markers of bone resorption and formation were obtained. Regional lower-limb dual-energy x-ray absorptiometry was performed at baseline and at 6, 12, 18, and 24 mo. Leg BMD and percent change from baseline significantly increased at 6 (percent change only), 12, 18, and 24 mo in the treatment group, but not in the placebo group. Urinary N-telopeptide, a marker of bone resorption, was significantly reduced during treatment with 1-alpha D₂, but markers of bone formation were not changed.