Solutions & prevention
Bone density scans (DEXA) and osteoporosis screening
Osteoporosis is a condition where bones become weaker and more likely to break, often without any warning until a fracture happens. A bone density scan, usually called a DEXA scan, is the main test used to measure how strong the bones are and to help assess the risk of fracture. Understanding when a scan is offered and what the results mean helps people take steps to protect their bones. This guide explains, in plain terms, what a DEXA scan is, who is offered one, and how the results are used. It is general education, not personal medical advice.
Education and reference only. This article explains how treatments work in plain language — it contains no doses and is not a substitute for advice from your doctor or pharmacist. Always discuss your own treatment with a qualified clinician.
What a DEXA scan is
A DEXA scan (dual-energy X-ray absorptiometry) is a special, low-dose X-ray test that measures bone density — essentially how strong and solid the bones are. It usually focuses on the areas most likely to break in osteoporosis, such as the hip and the lower spine. The scan is quick, painless and non-invasive: you lie on a padded table while a scanning arm passes over you, and you do not go inside a tunnel. It uses only a very small amount of radiation, much less than many ordinary X-rays. By measuring how much X-ray the bone absorbs, the scan estimates the amount of bone mineral present, which reflects bone strength. This measurement is the most widely used way to assess bone density and is a key part of judging someone's risk of breaking a bone.
Why bone density matters
Bones are living tissue that is constantly renewed, but with age, and for various other reasons, they can lose density and become more fragile. Osteoporosis means the bones have become weak enough that they may break after a minor fall or even a small knock, most commonly at the hip, spine and wrist. These fractures, especially of the hip and spine, can cause pain, loss of independence and serious health problems, so preventing them matters a great deal. The trouble is that low bone density usually causes no symptoms until a fracture happens, so it can go unnoticed. Measuring bone density with a DEXA scan allows weak bones to be identified before a break occurs, so that steps can be taken to strengthen them and reduce the chance of fractures in the future.
Who is offered a scan
In the UK, DEXA scans are not offered to everyone routinely; instead they are used when someone's risk of fracture suggests a scan would be helpful. A doctor often starts by assessing risk using a person's age, medical history and risk factors, sometimes with a risk-scoring tool, and then arranges a scan if this indicates it. Common reasons to consider a scan include being older, having already broken a bone after a minor injury, having a strong family history of osteoporosis or hip fracture, long-term use of certain medicines such as steroids, going through early menopause, or having other conditions or lifestyle factors that weaken bone, such as smoking, heavy drinking or being underweight. Because the approach is based on individual risk rather than a blanket screening programme, whether a scan is right for you is best decided with your GP.
Understanding the results
DEXA results are usually given as scores that compare your bone density with a healthy reference. The best known is the T-score, which compares your bone density with that of a healthy young adult. Broadly, a T-score in the normal range means good bone density; a somewhat reduced score suggests bone density that is lower than ideal but not yet osteoporosis, sometimes called osteopenia; and a more markedly reduced score indicates osteoporosis. However, the scan result is only part of the picture. Doctors interpret it alongside your age, previous fractures and other risk factors to judge your overall chance of breaking a bone, because two people with the same score can have quite different risks. This is why the result guides a conversation about what, if anything, to do, rather than being a simple pass or fail.
Protecting your bones
Whatever a scan shows, there is a lot people can do to keep their bones as strong as possible. Regular weight-bearing and muscle-strengthening exercise helps maintain bone and improve balance, which reduces falls. A balanced diet with enough calcium, and adequate vitamin D — which helps the body use calcium and may need a supplement, particularly in the darker months — supports bone health. Not smoking and keeping alcohol within sensible limits also help. Reducing the risk of falls at home, and having eyesight and any dizziness checked, lowers the chance of fractures. Where bone density is low or fracture risk is high, doctors may recommend specific medicines to strengthen bone and reduce the chance of breaks, alongside these lifestyle measures. Regular review helps keep the plan up to date. Looking after your bones is worthwhile at any age, well before problems appear.
In short
Key takeaways
- A DEXA scan is a quick, painless, low-dose X-ray test that measures bone density, usually at the hip and spine.
- Osteoporosis makes bones fragile and prone to fracture, often with no symptoms until a break happens, so measuring density helps spot risk early.
- Scans are offered based on individual fracture risk — such as age, previous fractures, family history or steroid use — not to everyone routinely.
- Results such as the T-score are interpreted alongside age and other risk factors to judge overall fracture risk, not as a simple pass or fail.
- Exercise, enough calcium and vitamin D, not smoking, limiting alcohol, preventing falls and, where needed, medicines all help protect bones.
Answers
Frequently asked questions
Does a DEXA scan hurt or involve a lot of radiation?
No. A DEXA scan is painless and non-invasive — you simply lie on a padded table while a scanning arm passes over you, and you do not go inside a tunnel. It uses only a very small amount of radiation, much less than many ordinary X-rays. The scan is quick, usually taking only a short time, and there is nothing to swallow and no injection. It is a straightforward, low-risk test.
Should everyone have a bone density scan?
Not routinely. In the UK, DEXA scans are offered based on a person's risk of fracture rather than to everyone. A doctor usually assesses risk using age, medical history and factors such as previous fractures, family history, steroid use or early menopause, sometimes with a scoring tool, and arranges a scan if it would be helpful. If you are concerned about your bone health or have risk factors, discuss with your GP whether a scan is right for you.
What does it mean if my bone density is low?
A low result, such as a reduced T-score, means your bones are less dense than ideal, which can range from osteopenia (lower than normal but not osteoporosis) to osteoporosis. It is interpreted alongside your age and other risk factors to judge your overall fracture risk. It does not mean a break is certain. Depending on the picture, your doctor may recommend lifestyle measures, vitamin D and calcium, and sometimes medicines to strengthen bone.
Go deeper
Related guides
Sources
Where this is drawn from
- National Institute for Health and Care Excellence (NICE). Osteoporosis: assessing the risk of fragility fracture (CG146). 2023.
- NHS. Bone density scan (DEXA scan): what it is and what to expect. 2024.
- Royal Osteoporosis Society. Understanding bone density scans and results. 2023.
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