4.3.3 Osteoporosis
Osteoporosis literally means“porous bones”；that is，bones that were once strong become fragile due to loss of bone density（Fig.4-4）.Osteoporosis is a metabolic bone disorder characterized by progressive decline of bone mass and bone quality，leading to bone fragility and an increased risk of fracture.Osteoporosis occurs most frequently in postmenopausal women，sedentary or immobilized individuals，and patients on longterm steroid treatment.
Fig.4-4 Osteoporosis
A major factor in osteoporosis is hormonal.Postmenopausal women are at a high risk for osteoporosis because estrogen production and bone calcium storage decrease with menopause.Significant risk has been reported in persons of all ethnic backgrounds.White and Asian women have the lowest general bone density and are at greater risk.
Classic characteristics of osteoporosis are fractures that occur in response to normal activity or minimal trauma，a loss of standing height of greater than 2 inches，and the development of the typical cervical kyphosis（dowager’s hump）.The clinical symptoms of this disease may include back pain，height loss，and a history of fractures.Bone mineral density（BMD）is often markedly reduced in osteoporotic patients with fractures.
Dual-energy X-ray absorptiometry（DXA）measurement of BMD provides the most accurate and precise tool to assess fracture risk.The DXA measurement，combined with age，history of previous fracture，and family history，gives the clinician the most accurate assessment of osteoporotic risk.
Efforts to prevent osteoporosis include adequate intake of calcium and engaging in weight-bearing exercise.Because of safety concerns，hormone replacement therapy（HRT）is currently being re-evaluated for use in the prevention of osteoporosis.Some drugs are available for reducing bone resorption and increasing bone density.
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Task 5 Fill in the blanks with proper words.
1.________is a condition characterized by progressive decline of bone mass and bone quality.(https://www.daowen.com)
2.________women，sedentary or immobilized individuals，and patients on long-term steroid treatment are susceptible to osteoporosis.
3.________refers to the permanent cessation of menstruation，usually occurring between the ages of 45-55.
4.A major hormonal factor of osteoporosis is the low production of________.
5.White and Asian women are at higher risk for osteoporosis，which suggests that________is a risk for osteoporosis.
6.Fractures，a loss of standing height，and the development of the typical cervical kyphosis（dowager’s hump）are classic________of osteoporosis.
7.Back pain，height loss and a history of fractures are the clinical________of osteoporosis.
8.Dual-energy X-ray absorptiometry（DXA）is an approach applied for________of bone mineral density.
9.Preventive measures for osteoporosis include adequate intake of________and engaging in weight-bearing exercise.
10.The application of________replacement treatment in preventing osteoporosis involves safety problems.