Study objective: To determine if calcitriol is an effective treatment in postmenopausal osteoporosis.
Design: Double-blind, randomized clinical trial of 2 years' duration.
Setting: University medical center with patients recruited by media announcements.
Patients: Eighty-six postmenopausal women with vertebral compression fractures.
Interventions: Patients were treated with calcitriol or placebo. Mean dose was 0.43 micrograms/d. Dietary calcium was 1000 mg/d (24.9 mmol/d). The medication dose and dietary calcium were adjusted for hypercalciuria or hypercalcemia.
Measurements and main results: No significant differences between placebo and control groups were seen in the percent change in total body calcium (0.4% +/- 1.0 compared with 0.0% +/- 0.9), single photon absorptiometry (-0.5% +/- 1.2 compared with -3.1% +/- 0.9) or dual photon absorptiometry (0.0% +/- 1.7 compared with -1.0% +/- 2.2). New fractures were seen in 16% of the placebo group and 26% of the calcitriol groups, so the difference in percent fractures was 10% (95% CI, -5.7% to 25.7%). Bone biopsies did not show changes in either group. The calcitriol group had significantly higher serum and urine calcium values, but renal function was not worse than in the placebo group.
Conclusions: Calcitriol is not an effective treatment for established postmenopausal osteoporosis.