Osteoporosis is a major public health problem. It is a skeletal disorder characterized by low bone mass and an increased susceptibility to fractures. In the United States, it affects more than 25 million people, accounts for 1.5 million fractures annually, and costs the nation in excess of $10 billion. The consequences of osteoporosis include decreased functional independence and increased morbidity and mortality. Osteoporosis is a multifactorial disease. The pathogenesis of the disorder has genetic, hormonal, and environmental influences that affect peak bone mass, perimenopausal bone loss, and age-dependent bone loss.