Do You Need a Bone Density Test?
Q. How often should I have a bone density test? And can I trust the results?
Bone mineral density tests measure bone loss and help doctors determine if you are at risk for, or have, osteoporosis. This bone-thinning disease is responsible for fractures of the wrist, hip, and spine and is most common among postmenopausal women. Thin women are at highest risk for this disease, but it also strikes those who smoke or drink heavily, or have a sedentary life style. The National Osteoporosis Foundation has also identified the following risks: advancing age, dementia, frail health, poor eyesight, and recurrent falls. Physicians' guidelines from the National Osteoporosis Foundation recommend bone density tests for all women over 65 and all postmenopausal women who have had a fracture or have any risk factors for osteoporosis.
The "gold standard" test for bone mineral density is called DXA (or DEXA) for Dual Energy X-ray Absorptiometry. It measures the density of bone in the spine, hip, or whole body and can detect bone loss as low as 1 percent. A newer test, pDEXA (the "p" for portable), measures bone density in the wrists, heels, or fingers and is a good substitute if you can't get a DEXA in your area. An even newer device, called Sahara Clinical Bone Sonometer, measures bone strength in the heel via ultrasound and should be widely available soon. While not as reliable as DEXA, it is simpler and can give you a pretty good idea of the state of your bones.
How often you need a bone density test is a decision you will make with your doctor -- but the reliability of these tests has been somewhat controversial. For some time, the medical establishment couldn't agree on how to interpret the results. What was normal, average bone loss and what was accelerated, worrisome bone loss? Most doctors now recommend having two or more tests over a two to five year period to track individual history. For instance, if you've had a test which revealed signs of osteoporosis, your doctor will most likely prescribe hormone replacement therapy to strengthen your bones, Fosamax (a bone-building drug), or Raloxifene (a designer estrogen). Your physician may want you to get another bone density test in a year to see if the drugs are working. Similarly, if your first test comes back fine -- your bones are strong -- your doctor may recommend another test in a year or two to see if anything changes.
Meanwhile, you should do all you can to keep your bones strong. Make sure you get between 1,000 and 1,500 mg of calcium daily, along with 400 IU of vitamin D to promote its absorption; eat leafy greens and soy foods (both are rich in calcium); and exercise regularly. Weight-bearing aerobic exercises, such as walking, running, and weight-lifting are proven protective measures. And believe it or not, doctors recommend gaining a little weight if you're especially thin -- thinness puts you at extra risk for the disease.