Placebo therapy for postmenopausal osteoporosis.

Eighteen postmenopausal osteoporotic (PMO) women on placebo therapy were followed for 1 year. Serial measurements of calcium balance and kinetics, bone histomorphometry, photon absorptiometry, and radiogrammetry were obtained. Few significant changes in balance and kinetics or bone histology were seen in these women over time. Photon absorptiometry and radiogrammetry of the femoral cortex showed a significant annual bone loss however. When compared with premenopausal and healthy postmenopausal women, the annual bone loss in those with PMO was significantly greater. The ability of balance studies, photon absorptiometry, and radiogrammetry to predict the magnitude of this bone loss was similar. Finally, there was an illustration of the use of the estimated variance provided by this study for estimating sample size for future studies.