Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fractures. It is not a component of normal aging but a disease process that is both treatable and preventable. Despite this fact, osteoporosis is a problem of global proportion. In the USA alone, osteoporosis affects 25 million women, most of whom are menopausal.
The disease is responsible for over 1.5 million total fractures a year, including 250,000 hip fractures. Following hip fractures, 20% of patients die within three months, 50% will require long-term care, and less than a third will ever return to normal activity. In economic terms, the public health costs for the treatment of osteoporosis related injuries approach $17 billion annually.
Although treatable, osteoporosis should and can be prevented by promoting bone health throughout a woman’s lifetime, by identifying individuals at risk for osteoporosis, and by implementing measures that promote both the development of peak bone mass and prevent bone loss.
Risk factors for osteoporosis are important predictors of fractures and should be considered in the evaluation and management of bone health in women. Those factors that may predispose a woman to develop osteoporosis include: a family history of osteoporosis being of oriental or Caucasian race, low body weight, some endocrinologic diseases, some medications used chronically, dietary problems (calcium deficiency), eating disorders, and, most importantly, lifestyle factors. Sedentary women, particularly those who smoke are at very high risk for developing osteoporosis. Excessive alcohol intake is also associated with a higher risk.
Recommendations for the prevention (and treatment) of osteoporosis include:
* Calcium intake 1200-1800 mg/day
* Vitamin D 400-800 IU/day for high risk patients
* Regular weight-bearing, muscle-strengthening exercise
* Avoid smoking and moderate alcohol consumption
The diagnosis of osteoporosis involves measurements of bone mineral density (BMD) which can be made at central sites, such as the spine or hip, or at peripheral sites, such as the radius (wrist), calcaneus (heel), or hand. All sites of BMD measurement seem to predict future fracture equally well at the site that was measured. But it is difficult to interpret the bone density at the spine or hip from a measurement made at the radius (wrist) or calcaneus (heel).
Moreover, when one attempts to monitoring therapy by remeasuring bone density, results may not be predictive. For example, medical therapy for osteoporosis may produce no effect at the radius(wrist), but increased density at the spine and femur. It is important therefore to measure BMD at the sites that are of clinical importance, particularly the spine and the hip, where fractures are likely to cause the greatest morbidity and mortality.
BMD measurements give us absolute values for each anatomic site. The values are then compared to other women of the same age (Z-score) or to normal young adults (T-score). The T-score is therefore defined as the number of standard deviations from the peak bone mass that a woman or man normally achieves in young adulthood. The guidelines of the World Health Organization define osteoporosis in patients whose bone density is < -2.5 standard deviations below the mean of young adults, or a T-score of < -2.5. Osteopenia is diagnosed when the T-scores are > -2.5 but < -1, while normal bone mineral density falls within a T-score of 1 or greater.
Reduced bone mass is correlated with an increased risk for future fractures and bone densitometry can be effectively used to manage patients with established osteoporosis and those that are at risk for osteoporosis.
Once a patient has been identified as (1) being at risk for developing osteoporosis, or (2) having osteoporosis, therapy is necessary and should always include lifestyle changes, an exercise program, adequate calcium and vitamin D intake, and sometimes medical therapy.
Available drugs for the treatment of osteoporosis include hormone replacement therapy (HRT), alendronate, raloxifene and calcitonin. All have been shown in prospectively randomized studies to preserve or increase BMD, although HRT and alendronate appear to increase bone density to a greater extent than either raloxifene or calcitonin.
Prevention of osteoporosis is by far the best therapy. It should begin in childhood and extend throughout life. Effective preventative programs must be directed at achieving peak bone mass from childhood to adulthood, maintaining bone mass from adulthood to middle age, and peventing bone loss from middle age to old age. It is a life-long process that involves healthful life style, proper nutrition and adequate supplementation with calcium and vitamin D, and administration of any of the available drugs, including HRT, alendronate, raloxifene or miacalcin. Prevention is the key to achieve control over this epidemic that threatens every woman throughout the world.