By John Messmer
People are living longer compared to 50 years ago. In the days when women did not expect to live beyond 65, osteoporosis was not much of a concern. As a larger portion of the population lives to 80, 90 and beyond, strong bones are essential.
Osteoporosis results when bones lose enough calcium to increase the risk of fracture. Osteopenia is the term for bones with low calcium but not low enough to be osteoporosis. When osteoporosis is severe enough, bones can break spontaneously or with minimal trauma.
A broken hip increases the risk of death by 10-20 percent and is associated with a high risk of another fracture in the next year. About 25 percent of those who sustain a hip fracture require long term nursing home placement and 40 percent never regain their prior level of independence. Fractures of the vertebrae can lead to kyphosis or “dowager’s hump,” which in addition to being uncomfortable can compromise heart and lung function. It is estimated that osteoporosis-related fractures cost us more than $17 billion annually. That could double or triple by 2040 with the increasing age of our population.
Osteoporosis is common. It is estimated to be present in 20 percent of non-Hispanic Caucasian and Asian, 10 percent of Hispanic and 5 percent of non-Hispanic black women over 50, and osteopenia in 52, 49 and 35 percent of these groups respectively. (Men with osteoporosis are fewer and typically older.) It does not happen suddenly, however. About 90 percent of a woman’s bone mass is present by age 18. She gives up calcium for each baby she has and by age 35, she begins to lose calcium faster than she replaces it. After menopause the rate of loss accelerates. Since it does not cause any symptoms until a break occurs, it is not possible to “feel” osteoporosis.
The risk of a fracture can be estimated by a bone density test, commonly through a dual-energy X-ray absorptiometry or DEXA scan. A DEXA is a special X-ray exam of the spine, hip and sometimes the forearm performed without special preparation, taking only a few minutes. The DEXA machine analyzes the amount of calcium in the bone and compares that to the amount that should be there at her age (the Z-score) and to the amount a healthy young woman would have (the T-score). If the T-score is less than -1.0, it means osteopenia; less than -2.5 means osteoporosis.
Fortunately, osteoporosis and osteopenia are preventable and treatable before damage occurs. Everyone needs at least 800 mg of calcium daily; those at higher risk for osteoporosis need at least 1,200 mg. Milk and yogurt have about 350 mg in 8 oz. and cheese has about 200 mg per oz. Calcium-fortified foods and calcium supplements can provide this essential mineral for those who cannot or will not consume dairy products.
Vitamin D is necessary to absorb and store calcium. Since the 1930’s, vitamin D-fortified milk has been the norm, with each cup of milk supplying 100 IU of vitamin D. Children and adults up to age 50 need a minimum of 200 IU daily, and adults over 50 should have 400 IU. Some authorities are recommending even more. Oily fish like salmon, cod, tuna, sardines and mackerel can supply 200 – 400 IU per 3 oz. serving.
Sunlight stimulates the production of vitamin D in the skin. Most people can meet their vitamin D needs depending on the season and cloud cover, with only 5-30 minutes of exposure to the face and arms without sunscreen twice a week between 10 a.m and 3 p.m. That amount of sunlight is unlikely to increase the risk of skin cancer, wrinkles or sunburn in all but the most sensitive fair-skinned people. Darker skin absorbs less, so exposure times need to be longer, but the risk of sun damage is less in darker skin. Northern latitudes receive less sunlight even in summer so northerners need 30 minutes exposure. Southerners need less.
Smoking and more than three alcoholic drinks per day take calcium out of bone. Exercise, particularly weight-bearing and strengthening exercises, encourages stronger bones and also reduces the chance of falling. This includes walking, jogging, stairs, weight lifting, Tai-Chi, dancing and so on.
If osteoporosis is present, treatment is available. The need for calcium and vitamin D remains, but there are various medications that can reverse osteoporosis. Each medication has pros and cons so it’s best to work out treatment with your physician.
The time to think about our bones is before osteoporosis happens. For more information on osteoporosis, go to www.niams.nih.gov/Health_Info/Bone/Osteoporosis/default.asp or visit Penn State Milton S. Hershey Medical Center Health Information Library online.
John Messmer is associate professor of family and community medicine at Penn State College of Medicine and a staff physician at Penn State Hershey Medical Center.