When should you get a bone density test?

Dr. Corinne Ancona-Young, a family medicine doctor with Sharp Community Medical Group, answers important questions about bone density and what the results from a bone density test mean.

What is bone density and why test it?
Bone density refers to the thickness or denseness of the bone.

“I use the analogy of a brick of cheese, with great bone density being the brick of solid cheddar cheese,” says Dr. Ancona-Young. “Conversely, Swiss cheese filled with holes represents osteoporotic bone, which has poor supporting structures and can easily collapse or break.”

Strong bones are important for your health. A bone density test, also known as a DXA scan, is a way to measure the strength of your bones. The test provides an X-ray analysis of your bones’ thickness. Most commonly, both hips and the lumbar spine vertebrae are examined because the bone tissue in these areas is the thickest.

When should someone get a bone density test?
It is recommended that the following people get a bone density test:

• Adults age 50 or older who have suffered a fracture or have a high risk of osteoporosis 

• Any woman who is post-menopausal (including a surgical menopause) 

• All women at age 65 

• All men at age 70

What happens during a bone density test?
A technician will position your legs precisely to get the best images, often using a foam block between the knees to rotate your hips. The technician may scan your lower arm in addition to the other hip and spine.

While lying still, a scanner arm will move over your hips and lower spine, taking images of your bone tissue and emitting a tiny dose of radiation. The test is painless and simple, and takes approximately 10 minutes.

The information from the X-ray machine automatically transfers to a computer, which then calculates the thickness, or denseness, of the bone tissue.

What do your DXA results mean?
A DXA scan compares your bone density with the bone density expected for a healthy adult of the same age, gender and ethnicity. It can show whether you have osteoporosis (a disease that makes your bones weak), your risk for breaking bones or whether your osteoporosis treatment is working.

The scoring system has specific benchmarks:  

• Zero (normal) or +1 (higher) is excellent 

• Any score that is -1 to -2.5 in postmenopausal women or men over 70 is considered osteopenia and is evidence that bone is breaking down faster than it is rebuilding  

• A score greater than -2.5 demonstrates osteoporosis

“It is important to understand that a diagnosis of osteoporosis isn’t made by the score of the DXA scan alone,” explains Dr. Ancona-Young. “This should only be determined after a thorough evaluation, which includes bone-specific lab tests, a physical examination and a review of the DXA scan report.”

“Osteoporosis is not a disease that you get because you are old, and you don’t have to live with it sitting back and waiting for your bones to break,” adds Dr. Ancona-Young. “Aggressive therapy options are available and able to safely rebuild bone and return you to your independent life.”

Talk with your doctor about whether a bone density scan is right for you or a loved one.