What is a Bone Density Test?

A bone density test determines if you have osteoporosis.

Doctors use bone density testing to:

• Identify decreases in bone density before you break a bone
• Determine your risk of broken bones (fractures)
• Confirm a diagnosis of osteoporosis if you've experienced broken bones
• Monitor osteoporosis treatment

Bone density tests are not the same as bone scans. Bone scans require an injection beforehand and are usually used to detect fractures, cancer, infections and other abnormalities in the bone.

Your bone density test results are reported in two numbers: T-score and Z-score.

• T-score is your bone density compared with what is normally expected in a healthy young adult of your sex.

 

T-score	What your score means
-1 and above	Your bone density is considered normal.
Between -1 and -2.5	Your score is a sign of osteopenia, a condition in which bone density is below normal and may lead to osteoporosis.
-2.5 and below	Your bone density indicates you have osteoporosis.

• Z-score is the number of standard deviations above or below what's normally expected for someone of your age, sex, weight, and ethnic or racial origin. If your Z-score is -2 or lower, it may suggest that something other than aging is causing abnormal bone loss. If your doctor can identify the underlying problem, that condition can often be treated and the bone loss slowed or stopped.

Bone density tests are usually done on bones that are most likely to break because of osteoporosis, including:

• Lower spine bones (lumbar vertebrae)
• The narrow neck of your thighbone (femur), next to your hip joint
• Bones in your forearm