A bone density scan (DEXA) measures how strong your bones are — and the result is a T-score you can actually understand. A T-score of −1 or higher is healthy, −1 to −2.5 is osteopenia, and −2.5 or lower suggests osteoporosis. The scan takes about 20 minutes, uses very low-dose X-rays, and is not something you need to prepare for. This guide explains who should get one, what the numbers mean, and what happens after. Reviewed 2026.
What a bone density scan is
A bone density scan — also called DEXA or DXA — measures how much calcium and other minerals are in your bones. Bones with more minerals are denser, so they tend to be stronger and less likely to break. The scan uses very low-dose X-rays, with radiation similar to about three days of normal life. It is not a tunnel scan and does not need an injection.
The scan usually measures the hip and spine — the two places bones break most often — and sometimes the wrist. It takes around 20 minutes. You lie on your back on a firm couch while a scanning arm passes over your body.
Who should get a bone density scan
You may be referred for a scan if you:
- have broken a bone from a minor fall or bump (a low-trauma fracture)
- have symptoms of spinal fractures — height loss, change in posture, or unexplained back pain
- have risk factors for osteoporosis — age, family history, long-term steroid use, very low body weight, early menopause
- are a woman over 65 (US guidance recommends routine screening from this age)
- are a postmenopausal woman under 65 with increased fracture risk
Note: a scan is not done to check for cancer, pain, or osteoarthritis. And some people over 75 may be offered osteoporosis medicine without a scan, because scans are less accurate at older ages and bone density is only one part of bone strength.
How to prepare
- Wear clothes without metal — zips, heavy buttons, belts, underwired bras. A hospital gown is available if needed.
- Bring a list of your medicines. You do not need to stop any medicine for the scan.
- You can eat and drink as normal.
- You may be asked to complete a short questionnaire about family history, medical history, and (if relevant) your last period.
- If you are pregnant, you will need to rearrange the appointment.
What the results mean: T-scores explained
If you are a postmenopausal woman or a man aged 50 or older, your result is reported as a T-score — the difference between your bone density and that of a healthy young adult (0).
| T-score | What it means |
|---|---|
| −1 or higher | Healthy bone density |
| −1 to −2.5 | Osteopenia — lower than normal, but not osteoporosis |
| −2.5 or lower | Osteoporosis — weak bones, higher fracture risk |
Fracture risk increases by about 1.5 to 2 times with each 1-point drop in T-score. If you are premenopausal or under 50, you get a Z-score instead — a comparison with people of your age, ethnicity, and sex. A Z-score of −2.0 or less may suggest bone loss from a medication or another condition.
What happens after the scan
Results usually arrive around three weeks after the scan, by email, text, letter, or phone call. If you have not heard within the expected time, contact the service that referred you.
Your bone density result is only one part of the picture. Your doctor combines it with your age, fracture history, and other risk factors to estimate your chance of breaking a bone. If that chance is high, you may be offered an osteoporosis medicine — sometimes without a scan, especially over 75.
Red flags: when to talk to your doctor
- you have broken a bone from a minor fall or bump
- you have lost height or noticed a stooped posture
- you have unexplained back pain that could be a spinal fracture
- you are postmenopausal with risk factors and have never had a bone density check
- you have been told you have osteopenia or osteoporosis and are unsure what to do next
What does not help
- Waiting for symptoms — osteoporosis is often silent until a fracture happens.
- Ignoring a low T-score — osteopenia is a signal to act, not a non-result.
- Repeating scans too often — follow-up timing depends on your treatment and risk; your doctor will advise.
- Unproven "bone-building" supplements — stick to calcium, vitamin D, and weight-bearing exercise unless your doctor recommends more.
Sources
- NIAMS (NIH) — Bone Mineral Density Tests: What the Numbers Mean: niams.nih.gov/health-topics/bone-mineral-density-tests-what-numbers-mean (last reviewed February 2025, accessed September 2026)
- Royal Osteoporosis Society — Bone density scan (DEXA/DXA): theros.org.uk/information-and-support/diagnosis-and-testing/bone-density-scan-dexa-dxa
- NHS — Osteoporosis: nhs.uk/conditions/osteoporosis
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