Sex steroids and the pathogenesis of osteoporosis

Significant bone loss occurs with aging in both men and women, leading to alterations in skeletal microarchitecture and increased fracture incidence. This chapter expresses that sex steroids play in the development and progression of osteoporosis in both men and women. Estrogen plays a central role in osteoblast biology, where it promotes bone marrow stromal cell differentiation toward the osteoblast lineage, increases preosteoblast to osteoblast differentiation, and limits both osteoblast and osteocyte apoptosis. Estrogen also has other important effects on suppressing bone resorption. Relative to postmenopausal women, elderly men on average lose one-half as much bone and sustain one-third as many fragility fractures. In addition to the effects of sex steroids, it is important to recognize that nonsex hormonal changes also occur with aging in both men and women. These include reductions in the production of growth factors important for osteoblast differentiation and function.