What is a Bone Density Test?
A bone density test, or scan is designed to check for osteoporosis; a disease that occurs when the bones become thin and weak. Osteoporosis happens when the bones lose calcium and other minerals that keep them strong. Osteoporosis begins after menopause in many women, and worsens after age 65, often resulting in serious fractures. These fractures may not only bring disability, but may affect longevity. As many as one-fourth of women who fracture their hip after age 50 die within one year.
What is osteoporosis?
Osteoporosis is a disease that occurs when the bones lose the calcium and structure that kept them strong. If often occurs after menopause (around 50) in women and in old age in men.
What is calcium?
Calcium is a mineral that helps build bone. After menopause when women start making less of the bone protecting hormone estrogen, they may need to increase their intake of calcium.
Most people today will get a bone density scan from a machine using a technology called Dual Energy X-ray Absorptiometry or DEXA for short.
This machine takes a picture of the bones in the spine, hip total body and wrist, and calculates their density. If a DEXA machine is not available, bone density scans can also be done with dual photon absorptiometry (measuring the spine, hip and total body) and quantitative computed tomography scans (measuring the spine). Bone density scanners that use DEXA technology to just measure bone density in the wrist (called pDEXA scans) provide scans at some drug stores. Yet, these tests are not as accurate as those that measure density in the total body, spine or hip - where most fractures occur.
Not all doctors routinely schedule this test. If the following factors apply to the patients they may need a bone density test.
- At risk for osteoporosis
- Is near menopause
- Has a broken a bone after a modest trauma
- Has a family history of osteoporosis
- Uses steroid or anti seizure medications
- Has had a period of restricted mobility for more than six months