A bone density test, also called densitometry, determines if you have osteoporosis — a disorder characterized by bones that are more fragile and more likely to break.
A bone density test uses X-rays to measure how many grams of calcium and other bone minerals are packed into a segment of bone. The bones that are most commonly tested are in the spine, hip and sometimes the forearm.
Bone density tests are easy, fast and painless. Virtually no preparation is needed.
Your bone density test results are reported in two numbers: T-score and Z-score.
Your T-score is your bone density compared with what is normally expected in a healthy young adult of your sex. Your T-score is the number of units — called standard deviations — that your bone density is above or below the average.
|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 likely have osteoporosis.|
Your 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 significantly higher or lower than the average, it may suggest that something other than aging is causing abnormal bone loss.