Calcitriol in postmenopausal women with osteoporosis - Tips from Other Journals

Date: June, 1992

Estrogen and calcium are commonly used to treat postmenopausal osteoporosis. Calcitriol has been considered for the treatment of osteoporosis because it increases intestinal calcium absorption, stimulates bone synthesis and decreases bone resorption. However, the results of studies of its efficacy are conflicting. One study found that calcitriol was ineffective in the treatment of established osteoporosis. Another found that it reduced bone loss by increasing calcium absorption and reducing bone resorption. A third study found that it increased spinal bone density and total body calcium. To compare the effects of calcium and calcitriol on the rate of new vertebral fractures in women with postmenopausal osteoporosis, Tilyard and colleagues conducted a prospective, randomized study of calcitriol therapy in women who had one or more vertebral compression fractures.

The study included 622 women. The 314 women in the calcitriol group received 0.25 [mu]g of calcitriol twice daily, and the 308 women in the calcium group received 1 g of elemental calcium as 5.2 g of calcium gluconate twice daily. The rate at which new fractures developed, as measured by lateral roentgenography, was used to determine the efficacy of treatment. A fracture was defined as a decrease of 15 percent or more in the anterior or posterior height of the body of each vertebra from T4 through L4.

After the second year of treatment, the calcitriol group had a significantly lower rate of new vertebral fractures than the calcium group (nine fractures versus 25 fractures per 100 patient-years). After the third year, 10 fractures per 100 patient-years had occurred in the calcitriol group, compared with 32 fractures per 100 patient-years in the calcium group. In addition, 11 women in the calcitriol group had 11 peripheral fractures, while 22 women in the calcium group had 24 peripheral fractures. Among women initially classified as having mild to moderate osteoporosis (five or fewer fractures), four fractures occurred in the calcitriol group and 31 occurred in the calcium group after the third year of treatment. The incidence of side effects was similar in both groups.

The study results indicate that calcitriol therapy in women with postmenopausal osteoporosis is safe and effective in reducing the incidence of new vertebral fractures. (New England Journal of Medicine, February 6, 1992, vol. 326, p. 357.)

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