CELLULAR AND MOLECULAR MECHANISMS OF OSTEOPOROSIS

Osteoblasts and osteoclasts are derived from progenitors originating i n the bone marrow, and the process of bone remodeling is controlled by growth factors and cytokines which regulate the birth and death of th ese cells, An overproduction of osteoclasts relative to the need for r emodeling, and an undersupply of osteoblasts relative to the need for cavity repair, represent the fundamental pathophysiologic changes in p ostmenopausal and age-related osteopenia, respectively. As in these tw o forms of the disease, the osteoporosis induced by glucocorticoid exc ess is also caused by changes in the birth and death of bone cells, an d in particular a decrease in osteoblastogenesis in the bone marrow, a nd an increased rare of osteoblast and osteocyte apoptosis. (C) 1998. Editrice Kurtis.