Effects of calcitriol or calcium on bone mineral density, bone turnover, and fractures in men with primary osteoporosis: A two-year randomized, double blind, double placebo study

Osteoporosis in men is an emerging public health problem. As calcitriol red uces the rate of vertebral fractures in osteoporotic postmenopausal women, we conducted a prospective study of this treatment in men with primary oste oporosis. Our study was a 2-yr, randomized, double masked, double placebo-c ontrolled trial of calcitriol (0.25 mug twice daily) or calcium (500 mg twi ce daily) in 41 men with primary osteoporosis and at least 1 baseline fragi lity fracture. Thirty-three men (85%) completed the study. There were no differences in baseline characteristics. Spinal and femoral n eck bone mineral densities at 2 yr were unchanged in both groups. Serum ost eocalcin decreased in both groups by 30% (P < 0.05), whereas urine N-telope ptide cross-links decreased only in the calcium group by 30%, (P < 0.05). A fter 2 yr, fractional calcium absorption increased by 34% (P < 0.01) in the calcitriol group. Nineteen incident fragility fractures occurred (14 verte bral and 5 nonvertebral) in 7 men. Over 2 yr, the number of men with verteb ral fractures (6 vs. 1; P = 0.097) was similar in both groups. In conclusion, the efficacy of calcitriol remains unproven as a single agen t for the treatment of osteoporosis in men.