Bone density
Bone density, or bone mineral density, is the amount of bone mineral in bone tissue. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging.[1] Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of hospitals or clinics. The measurement is painless and non-invasive and involves low radiation exposure. Measurements are most commonly made over the lumbar spine and over the upper part of the hip.[2] The forearm may be scanned if the hip and lumbar spine are not accessible.
There is a statistical association between poor bone density and higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to substantial medical costs, inability to live independently and even risk of death.[3] Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength.
Prevention[edit]
To prevent low bone density it is recommended to have sufficient calcium and vitamin D.[17][18] Sufficient calcium is defined as 1,000 mg per day, increasing to 1,200 mg for women above 50 and men above 70.[18] Sufficient vitamin D is defined as 600 IUs per day for adults 19 to 70, increasing to 800 IUs per day for those over 71.[18] Exercise, especially weight-bearing and resistance exercises are most effective for building bone. Weight-bearing exercise includes walking, jogging, dancing, and hiking. Resistance exercise is often accomplished through lifting weights.[19] Other therapies, such as estrogens (e.g., estradiol, conjugated estrogens), selective estrogen receptor modulators (e.g., raloxifene, bazedoxifene), and bisphosphonates (e.g., alendronic acid, risedronic acid), can also be used to improve or maintain bone density. Tobacco use and excessive alcohol consumption have detrimental effects on bone density.[20][18] Excessive alcohol consumption is defined as more than one standard-sized alcoholic beverage per day for women, and drinking two or more alcoholic beverages per day for men.[18]