DEAR MAYO CLINIC: What is a bone density test? Is it necessary to have one even if I'm healthy? I am a 67-year-old woman and I exercise daily.
ANSWER: A bone density test uses x-rays to measure how much calcium and other minerals are in a section of your bone. The purpose of this test is to find out if you have osteoporosis -- a disease characterized by weak and brittle bones that break easily. A bone density test also can show if you may be at risk for developing osteoporosis.
Several other groups of people who are at high risk for osteoporosis may benefit from a bone density test, too. They include those who take certain kinds of drugs that can interfere with the body's process of rebuilding bone. Examples of these drugs include steroid medications such as prednisone, and immunosuppressant medications such as those taken after an organ transplant or a bone marrow transplant.
People older than 50 who've broken a bone and individuals who've lost one-and-a-half inches of height or more also may need a bone density test to screen for osteoporosis.
A bone density test is useful for detecting osteoporosis because the lower a person's bone mineral content, or the less dense bones are, the more likely they are to be weak and break easily. How often you need follow-up bone density tests depends on the results of your first test, as well as other factors, such as your personal and family medical history.
Results of the test are reported in a measurement known as a T-score. A T-score of -1 or higher is normal. A score of -2.5 or lower is osteoporosis. The range between normal and osteoporosis is considered osteopenia -- a condition where bone density is below the normal range and puts a person at higher risk for developing osteoporosis. Osteopenia also raises the risk for breaking a bone.
To help keep your bones healthy as you get older, there are a number of bone-friendly lifestyle choices you can make. You've already taken one important step by exercising regularly. If you aren't already doing so, include a combination of strength training exercises along with weight-bearing exercises such as walking, jogging, running, stair climbing, skipping rope or skiing.
Get plenty of calcium in your diet every day, too. Good sources of calcium include dairy products, almonds, broccoli, kale, canned salmon with bones, sardines, and soy products, such as tofu. You also need vitamin D, which helps your body absorb calcium. Good sources of vitamin D include oily fish (such as tuna and sardines), egg yolks and milk fortified with vitamin D. Sunlight contributes to the body's production of vitamin D, as well.
Smoking and drinking alcohol can have an effect on your bone health. Research suggests that tobacco use contributes to weak bones. Similarly, regularly having more than two alcoholic drinks a day raises your risk of osteoporosis, possibly because alcohol can interfere with the body's ability to absorb calcium. With this in mind, to protect your bones, limit the amount of alcohol you drink and don't smoke.
Talk to your doctor about getting a bone density test. Also take time to discuss with him or her any concerns you may have about your bone health, including factors that could increase your risk for osteoporosis. Taking these steps can help ensure good bone health now and in the future. -- Bart Clarke, M.D., Endocrinology, Mayo Clinic, Rochester, Minn.
(Medical Edge from Mayo Clinic is an educational resource and doesn't replace regular medical care. E-mail a question to email@example.com. For more information, visit http://www.mayoclinic.org.)
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