What is a Bone Density Test?
A bone density test is used to see if someone has osteoporosis, which is a disease that makes bones fragile and likely to break. In the past, it took bones breaking to determine if a patient had osteoporosis, but by then the bones were already weak. A bone density test can detect the risk of breaking bones. Doctors can look for bone density decreases and the risk of fracture, confirm an osteoporosis diagnosis, and monitor the treatment of osteoporosis with this test. How is a bone density test done? By using “X-rays to measure how many grams of calcium and other bone minerals are packed into a segment of bone”. Typically, the hip, forearm, and spine are tested. The higher the “bone mineral content” the more dense the bones are, and that determines how strong they are. A bone density test is not a bone scan. Scans “require an injection beforehand and are usually used to detect fractures, cancer, infections and other abnormalities in the bone”.1
The bone density test results may indicate osteoporosis. It is more common in older women, but men can also develop this issue. The test is recommended for people who have lost at least 4 centimeters in height, possibly due to compression fractures of the spine. It is also suggestion for patients how have had “fragility fractures”, such as those caused by a sneeze or cough. Some patients who take certain drugs for long period of time, such as steroids (prednisone) may need the test as these medications can interfere with the process of building bones. Patients who receive a transplant may also get this type of test, because anti-rejection medications also interfere with building bones. Patients who have their estrogen hormone levels drop, such as in menopause or due to cancer treatments, may also need this test. Some prostate cancer treatments reduce the levels of testosterone in men, and “lowered sex hormone levels weaken bone”.2
Bone Density Test Procedure
The test is usually performed on lumbar bones, the neck of femur by the hip, and forearm bones. If done at a hospital, the bone density test will most likely be done on a “central device, where you lie on a padded platform while a mechanical arm passes over your body”. The radiation exposure is low, and the test takes between 10 and 30 minutes. For the wrist, finger, or heel, a portable machine, which is smaller, may be used. These instruments are called “peripheral devices”, and they can be found in pharmacies. The tests done with these instruments are not as expensive as the ones done with central devices. Bone density varies throughout the body, so a heel test is not as accurate as a hip or spine test; therefore, if a peripheral device test is positive, a doctor will want to have a “follow-up scan at (the) spine or hip”.3 The tests require no preparation, but patients having a hospital test should inform their doctors if they have had a recent “barium exam or contrast material injected for a CT scan or nuclear medicine test”, since the contrast materials could interfere with the test.4 Bone density test results yield T-scores. A T-score of -1 or higher is normal. Between -1 and -2.5 is “low bone density or osteopenia”. At -2.5 or below, a patient is diagnosed with osteoporosis.5
The most common medications for osteoporosis are bisphosphonates (Fosamax, Actonel, Boniva, Reclast). People with lowered kidney functioning cannot take these. Sometimes estrogen and other hormone-like medications are used to treat or prevent osteoporosis. Evista is an example of this, but estrogen therapy can increase the risk of some cancers and heart attacks. A newer medication, Prolia, has been “shown to reduce the risk of osteoporotic fracture in women and men”. Forteo is a drug for post-menopausal women and for men who have had fractures, low bone density, or whose osteoporosis has been caused by steroids. It is said to be “the only osteoporosis medication that has the potential to rebuild bone and actually reverse osteoporosis…somewhat”.6 To prevent osteoporosis, or to stop further damage, it is important to prevent falls, exercise, and have proper nutrition, such as getting enough vitamin D and calcium.7 To prevent falls, it is important to make the home safe by clearing stairs and walkways, using rug adhesive and non-slip mats, using handrails, keeping the house well-lit, keeping frequently-used items within reach, walking around in rubber-soled shoes instead of barefoot or in socks, and avoiding walking on an icy or wet sidewalk, choosing the grass instead or using kitty litter or salt on the ice. A cane or walker may be needed, and caution should be used when stepping onto or off of a sidewalk.8
Learn more about osteoporosis.