Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 8. Vitamin D metabolites and analogs in the treatment of osteoporosis.

OBJECTIVE: To review recent findings on the skeletal actions of vitamin D and to examine results of the latest clinical trials of vitamin D in the treatment of osteoporosis. OPTIONS: The vitamin D analog 1-alpha hydroxycholecalciferol (1 alpha-OH-D3); the vitamin D metabolite calcitriol. OUTCOMES: Fracture and loss of bone mineral density in osteoporosis; increased bone mass, prevention of fractures and improved quality of life associated with vitamin D therapies. EVIDENCE: Relevant laboratory and clinical studies and reports were examined. Greatest reliance was placed on recent large-scale, randomized, controlled trials; others were noted and their methods critiqued. Clinical practice in Japan was also considered. VALUES: Reducing fractures, increasing bone mineral density and minimizing side effects of treatment were given a high value. BENEFITS, HARMS AND COSTS: Vitamin D maintains the dynamic nature of bone and so presumably helps to keep it healthy. Calcitriol and 1 alpha-OH-D3 may be effective in increasing bone mass and preventing fractures in osteoporosis. Calcitriol may be an alternative treatment in the prevention and management of corticosteroid-induced osteoporosis. Possible side effects of vitamin D analogs and metabolites are hypercalcemia, hypercalciuria, renal calcification and renal stones. RECOMMENDATIONS: The use of 1 alpha-OH-D3 for the treatment of osteoporosis in Canada cannot be supported without larger and longer randomized, controlled clinical trials. Calcitriol appears to prevent vertebral fractures in patients with osteoporosis. More information is needed on its mechanism of action and efficacy in preventing hip fractures. Future studies should focus on comparisons with other effective therapies and on determining whether its effect on fractures is greater than that achieved through improved vitamin D nutrition. Patients taking calcitriol at dose levels required for antifracture effects should be monitored for serum and urine calcium response to the drug. Calcitriol should not be given to patients whose calcium intake is at current generally recommended levels. At present, prescription of calcitriol for the treatment of osteoporosis should be reserved for physicians with a special interest in the treatment of metabolic bone disease.