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By Vincent T. Brandeis, M.D.
Added 11/30/2009
Osteoporosis-decreased bone mass and weakened bone structure-is the most prevalent bone problem in the elderly, resulting in bone fractures. It currently affects 10 million Americans (four times more women than men) and threatens some 44 million more who have low bone mass (osteopenia) but are not yet past the threshold for osteoporosis.
Osteoporosis is generally associated with aging, and in women, the loss of estrogen after menopause is the principal predisposing factor. It is therefore one of the three major healthconcerns- along with cardiovascular disease and breast/endometrial cancer- in the medical care of post-menopausal women.
Bone formation is daily process of breakdown and building. In earlier years, the rate ofbreakdown and building are roughly balanced, but with age-after menopause, for women-bone breakdown becomes accelerated and surpasses bone building activity. By age 80, women would have lost about 30 percent of their bone mass.
Primary osteoporosis is the result of cumulative bone loss as people age, while secondaryosteoporosis results from a variety of medical conditions that affect bone health. Twenty to thirty percent of post-menopausal women and half of men with osteoporosis have secondary causes. Use of glucocorticoids is the most common secondary cause, and its association with increased risk of fracture is well established.
Attaining optimal bone mass is necessary to prevent osteoporosis and subsequent fractures.Studies show that even a 10% increase in bone mass would decrease the risk of hip fracture by 30%.
Heredity is the greatest risk factor for osteoporosis-up to 80% of variability in peak bone mass is due to genetic factors.
Other factors that affect bone mass accumulation as people mature are nutrition, physical activity, health status in the growth years, as well as smoking and alcohol use. The same factors in pregnant women affect bone development in the fetus.
The process of bone remodeling in adults generally involves two weeks of bone resorption (when bone cells break down) followed by a 3-4 month phase of bone formation. This process, in effect, removes old bone and forms new bone, while repairing microfractures that result from repeated stresses.
Osteoporosis is diagnosed by an imaging technique called dual energy X-ray absorptiometry (Dexa) which measures bones mass density (BMD) in the spine, hip and forearm. The patient's BMD is compared to the BMD of young healthy adults of the same sex: A difference of 1-2.5 standard deviations below that norm is osteopenia, and a difference of greater than 2.5.S.D. Is diagnostic of osteoporosis. DEXA is used subsequently to monitor how effective treatment is by showing if BMD has increased, decreased or remained the same.BMD is a strong predictor of fracture risk, as it accounts for 75-85% of bone strength. But even patients with osteopenia are at high risk for fractures.
In general, women aged 65 or older and men aged 70 or older should be screened for BMD. But screening should be done earlier for post-menopausal women with risk factors for osteoporosis; men and women with a family history of vertebral or hip fracture, or who have had a fragility fracture, or are taking medications associated with bone loss.
A fall causes nearly 90% of all fractures in older persons, and 20%-30% of such falls result in moderate to severe injuries. Therefore, fall prevention should be routine care for all older persons, with practical home measures like good lighting, no loose rugs, support bars along stairways and in bathroom.
Early identification-and therefore, early treatment-can substantially reduce the risk of osteoporotic fractures. Prevention and treatment combine non-pharmacologic approaches with pharmacologic (drug-based) therapies.
Non-pharmacologic approaches include reduced smoking and alcohol consumption, and regular weight-bearing and muscle- strengthening exercise. The patient should also be screened for secondary causes of osteoporosis (blood tests for calcium and hydroxy- Vitamin D levels).
The most basic 'drug' therapy is calcium and Vitamin D. A calcium intake of at least 1200mg/day and Vitamin D (D3 better than D20 of 800-1000 IU/day are recommended for all individuals aged 50 or older. Dietary sources are best-dairy products and vegetables (spinach, beans, and peas) for calcium, fatty fish for Vitamin D-but supplements are convenient and insure dose compliance.
FDA-approved drugs for the prevention and treatment of osteoporosis belong to a chemical family called biphosphonates. Two of them- alendronate (Fosomax) and risedronate (Actonel)-have been evaluated for up to 10 years of treatment and their long-term safety profile is well-established. So is their effectiveness in improving bone density and consequently, in preventing spinal and hip fractures, which are potentially the most serious for older people.
Patients undergoing treatment to prevent or treat osteoporosis should be educated by their physician about the implications of the disease, and be given simple and clear instructions, oral and in writing, on how to take their medications and drug supplements properly.
They should also be followed up to assess their compliance and progress, to address any concerns, and to manage any side effects.
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