Prevention of postmenopausal bone loss by low and conventional doses of calcitriol or conjugated equine estrogen

Objectives: Estrogen deficiency is the most common cause of postmenopausal osteoporosis and estrogen replacement is well known to retard postmenopausa l bone loss. Calcium supplement alone is generally considered to be insuffi cient for the prevention of bone loss associated with estrogen deficiency w hile the role of calcitriol is unclear. In the present study we examined th e efficacy different doses of estrogen or calcitriol in the prevention of p ostmenopausal bone loss in Thais. Methods: The subjects consisted of 146 Th ai women no more than 6 years postmenopausal. The subjects were randomly al located to receive 750 mg supplemental calcium alone, calcium and conjugate d equine estrogen (CEE) at 0.3 or 0.625 mg, calcium and calcitriol at 0.25 or 0.5 mu g daily. Those receiving CEE also took 5 mg medrogestone for 12 d ays each month. BMD at L2-4 and femoral neck were measured at baseline 1 ye ar and 2 years after treatments. Data were expressed as mean +/- S.E. Resul ts: Subjects on supplemental calcium alone had approximately 2.5% decreases in L2-4 (P < 0.05) and femoral BMD (P < 0.01) at 2 years. CEE (0.3 mg) res ulted in 3.20 +/- 1.2% increase in vertebral BMD (P<0.05) while no signific ant change in BMD was demonstrated at the femoral neck. Likewise, 0.625 mg of CEE induced 5.4 +/- 1.4% increase in vertebral BMD at 2 years (P < 0.001 ) without change in the femoral BMD. In regard to calcitriol, no significan t change in vertebral or femoral BMD was demonstrated with either 0.25 or 0 .5 mu g calcitriol. Conclusion: We concluded that calcitriol is effective i n the prevention of early postmenopausal bone loss in Thais. It represents an option for the prevention of osteoporosis in postmenopausal women who ar e contraindicated for estrogen replacement. (C) 2000 Elsevier Science Irela nd Ltd. All rights reserved.