Pathophysiology of age-related bone loss and osteoporosis

Age-related bone loss in women and in men is driven, in large part, by changes in sex steroid production or availability and by secondary hyperparathyroidism. Superimposed on these mechanisms, other factors such as vitamin D deficiency, intrinsic defects in osteoblast function, impairments in the growth hormone/IGF axis, reduced peak bone mass, age-associated sarcopenia, and various sporadic factors also contribute to bone loss and increased fracture risk in the elderly. An improved understanding of the relative importance of these various factors in the causation of bone loss should lead to enhanced preventive and therapeutic approaches for involutional osteoporosis, which, if left unchecked, is likely to impose an increasing health care burden on society.