Postmenopausal osteoporosis: epidemiology, pathophysiology and treatment.

Osteoporosis is an important age-related disease constituting a major health problem in most developed societies especially among postmenopausal women who are expected to live well into the 80s. An estimated total of about 75 million people in the USA, Europe and Japan are afflicted by the disease. It is often the underlying cause of spine, wrist and hip fractures. Spinal fracture leads to pain and loss of height but a hip fracture may result in disability or as a consequence of long-lasting immobilisation even death. The financial cost to governments of such fractures is enormous and runs into the ' region of US$ 18 billion1 and 500 pounds sterling2 each year in the United States of America and the United Kingdom respectively. Bone mass increases rapidly in growing children and adolescents, reaching a peak in adults between the second and third decade. After the age of 35-40 years, bone mass begins to decline. Men lose bone mass at approximately the same rate over their lifetime; in women however, the rate of bone loss increases dramatically after menopause or oophore~tomy.~ The bone mass in women after the age of 50 is only two-thirds of that found in men.4 These two factors lower initial adult bone mass and a more rapid rate of bone loss, combine to produce a high incidence of osteoporosis in older women. Postmenopausal osteoporosis can be prevented and treated. While most other therapies stabilise rather than restore bone mass, it is now widely accepted that the best prevention and treatment method in postmenopausal women is hormone replacement therapy. It is the only treatment shown unequivolcally to prevent loss of bone mass and to reduce the risk of fracture. In addition, it may be used for stabilising bone mass in established osteoporosis in postmenopausal women. tissue leading to enhanced bone fragility, and 3. a consequent increase in fracture risk (particularly of the spine, wrist and hip).s Using this definition, patients may be diagnosed as osteoporosis even where fracture has not yet occurred and so osteoporosis is often termed a "silent" condition which can be categorised further into: