What is bone densitometry? Bone densitometry is a scan (test) that measures your bone density (thickness). Bone densitometry is also called a dual energy x-ray absorptiometry (DXA) scan. DXA scans are normally done on your hip, spine, or forearm (lower arm). A DXA scan can also be done of your entire body. DXA scans use a radiation beam to take pictures of your bones. The pictures show minerals, such as calcium, inside your bones. The minerals in your bones help keep them strong and healthy. The DXA scan shows if your bones have lost needed minerals, causing them to become weak.
Why would I need bone densitometry? Healthy women age 65 or older, and healthy men age 70 or older, should have a DXA scan. Younger women and men who are at high risk for bone loss should also have a DXA scan. Ask your caregiver for more information about the following reasons to have a DXA scan:
To diagnose osteoporosis: Osteoporosis is a condition that occurs when you lose bone density and bone tissue. Your bones may have a sponge-like look from the bone loss. With osteoporosis, your bones weaken, and you are at high risk for bone fractures (breaks). The condition is more common in women, but can also occur in men. You are at increased risk for osteoporosis if you have other family members with the condition.
To check your risk for bone fractures: When you begin to lose bone density, your risk for bone fractures increases. Fractures can more easily occur when you fall, even if you fall from a ground-level position. Common fractures that occur with bone loss include hip fractures and vertebrae fractures. Your vertebrae are the bones in your back that are linked together to form your spine. A DXA scan may also be done to check for a fracture if you are having symptoms. Some fractures are painful, and may cause symptoms such as back pain or pain when you walk. Vertebrae fractures may also cause you to lose height (become shorter).
To monitor changes in your bone mineral density: If another DXA scan showed low levels of bone loss, you may need a follow-up DXA scan. A follow-up DXA scan helps your caregiver see if your bone loss is worse. You and your caregiver may learn if you need treatment for your bone loss.
To monitor treatment for bone loss: You may need a DXA scan if you have known bone loss and are taking medicines to treat it. The DXA scan can show if the medicines are helping to make your bones stronger.
What increases my risk for bone loss?
Diet and low body weight: Eating a diet low in calcium and vitamin D increases your risk for bone loss. Weighing 127 pounds or less can increase your risk for bone loss. People with eating disorders, such as anorexia nervosa, can also have low body weights leading to bone loss. Ask your caregiver for more information about eating disorders that can lead to bone loss.
Low estrogen levels: Women with low levels of the hormone estrogen are at increased risk for bone loss and osteoporosis. Hormones are natural body chemicals. Estrogen levels are lower in women who are entering, or at menopause. Menopause occurs when a woman no longer has a monthly period. Athletes who rarely, or never, get their periods may also have low estrogen levels.
Medical problems: Medical problems that can lead to bone loss include diabetes mellitus (high blood sugar). Hyperthyroidism (too much thyroid hormone) and hyperparathyroidism (too much parathyroid hormone) can also lead to bone loss. With celiac disease, your body does not absorb nutrients, which may lead to bone loss. Ask your caregiver for more information about these and other medical conditions that increase your risk for bone loss.
Medicines: Certain medicines taken for long periods of time can lead to bone loss. These medicines include steroids and androgen deprivation therapy for men. Long-term steroid use may be needed to treat inflammation (swelling) from rheumatoid arthritis, lung disease, and Crohn's disease. Androgen deprivation therapy may be needed to decrease the level of androgens (male hormones) in the body. This therapy treats certain male cancers or may be given after an orchiectomy (testicle removal). Ask your caregiver about other medicines that may cause bone loss.
Prior fractures: Having had broken bones in the past increases your risk for weakened bones and bone loss.
Prolonged immobilization: Having a medical or physical condition that keeps you from moving freely may lead to bone loss. Prolonged immobilization can occur if you are on long-term bedrest or you cannot walk.
Smoking and alcohol abuse: Smoking and alcohol abuse can increase your risk for bone loss. Alcohol abuse occurs when you drink too much alcohol, too often. Alcohol is found in beer, wine, whiskey, and other adult drinks. Talk with your caregiver if you smoke or drink alcohol and need help to stop.
What may be needed before having bone densitometry?
- You may be asked to sign a consent form (legal paper) before your procedure. This gives your caregiver permission to do the DXA scan. Make sure all of your questions have been answered before signing the consent form.
- If you take calcium supplements, you may be told not to take them the day of your DXA scan.
- You will need to remove any metal that is near the body area being scanned. This includes jewelry, clothing with zippers, coins, body piercings, or an underwire bra.
What happens during bone densitometry? You will lie on the DXA scan table on either your back or your side. If your hip is being scanned, you will need to turn your foot and hip slightly inward. Pillows or cushions may be used to support your back and help you stay in one position. Do not move during the scan so the pictures of your bones are clear. Once you are positioned, the scanner passes over the area and sends pictures to a screen. The DXA scan may last between 10 and 30 minutes, depending on the area being scanned.
What happens after bone densitometry? When your DXA scan is complete, you may be able to go home. Ask your caregiver when you will get the results of your DXA scan.
What are the risks of having bone densitometry?
- If the pictures from your DXA scan are not clear, you may need another scan. The scan may not show areas of bone loss, and you may not get needed treatment. The scan may show abnormal bone density when you have had no bone loss. If this occurs, you may get treatment you do not need.
- If you do not have the DXA scan, you may have bone loss that is not found. If you have unknown bone loss, your risk for falls and bone fractures increases. If you have an unknown fracture, your pain and other symptoms may get worse. You may not get needed treatment if you have bone loss, a bone fracture, or osteoporosis. Talk with your caregiver if you have questions or concerns about having a DXA scan.
Where can I find more information? Contact the following:
- American Academy of Orthopaedic Surgeons
6300 North River Road
Rosemont , IL 60018-4262
Phone: 1- 847 - 823-7186
Web Address: http://www.aaos.org/
- National Osteoporosis Foundation
1150 17th Street NW, Suite 850
Washington , DC 20036
Phone: 1- 202 - 223-2226
Phone: 1- 800 - 231-4222
Web Address: http://www.nof.org
When should I call my caregiver? Call your caregiver if:
- You are late or cannot make it to your DXA scan.
- You are a woman and think you are pregnant.
When should I seek immediate care? Seek immediate care or call 911 if:
- You fall and think you may have a bone fracture.
- Your condition, for which you are having the DXA scan, or symptoms, such as pain, suddenly get worse.
You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.
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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.
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