DEXA, also written as DXA, is a bone density test that uses a very small amount of X-ray radiation to measure how strong your bones are. It is one of the standard tests doctors use to look for bone thinning, osteopenia, and osteoporosis.
Because bone loss often happens silently, a DEXA scan is usually done before a fracture happens, not after. It helps doctors estimate fracture risk and decide whether monitoring, lifestyle change, or treatment is needed.
What does DEXA stand for?
DEXA or DXA stands for dual-energy X-ray absorptiometry.
Patients do not need to memorize the full name. What matters most is that it is a quick, low-dose bone density test.
What is a DEXA scan used for?
Doctors use DEXA to:
- Measure bone mineral density
- Screen for osteopenia or osteoporosis
- Estimate fracture risk
- Monitor whether bone loss is getting worse
- Follow response to treatment in some patients
It is most commonly used to assess the hip and lower spine.
Is DEXA the same as a regular X-ray?
Not exactly.
A DEXA scan uses X-ray technology, but it is designed specifically to measure bone density rather than just produce a standard picture of the bone. It uses a very low radiation dose and gives doctors numerical information about bone strength.
Who might need a DEXA scan?
Your doctor may recommend a DEXA scan if you:
- Are at risk for osteoporosis
- Have had a low-trauma fracture
- Are older and being screened for bone loss
- Use medicines that can weaken bone, such as long-term steroids
- Have a medical condition linked to low bone density
- Need follow-up for previously known osteopenia or osteoporosis
What parts of the body are usually scanned?
Most DEXA scans focus on:
- The hips
- The lower spine
In some situations, other areas such as the forearm may be assessed. In some children and selected adults, whole-body assessment may also be used for specific clinical reasons.
Will the scan hurt?
No. A DEXA scan is painless.
You simply lie still while the scanner passes over the area being measured. There are no injections, and the scan is noninvasive.
Do I need to prepare?
Preparation is usually simple.
You may be asked to:
- Wear comfortable clothing without metal around the area being scanned
- Avoid calcium supplements for a period before the exam, often 24 hours
- Tell the team if you recently had a barium study or another imaging test with contrast or tracer
- Tell the team if you might be pregnant
Your imaging center will give the exact instructions for your appointment.
Can I eat or drink before a DEXA scan?
Usually yes. Most DEXA scans do not require fasting.
How long does the scan take?
A DEXA scan is usually quick. The imaging itself often takes around 10 to 20 minutes, though the total visit may be a bit longer.
Is the radiation high?
No. DEXA uses a very low dose of radiation compared with many other imaging tests.
Even so, because it is still an X-ray-based study, it is important to mention possible pregnancy before the scan.
Can children have a DEXA scan?
Yes, when medically needed. In children, DEXA may be used in selected situations where doctors need to monitor bone health, growth-related bone issues, or conditions that affect bone strength.
The interpretation of results in children is different from that in adults, so pediatric DEXA needs the right clinical context.
What do the results mean?
DEXA results help show whether your bone density is:
- Within a healthy range
- Lower than expected
- In the osteopenia range
- In the osteoporosis range
Adults may hear terms like T-score and Z-score. Your doctor will explain which score matters most in your situation and what it means for your fracture risk and treatment plan.
How often do I need one?
That depends on why you are having it. Some people only need occasional screening, while others need repeat scans to monitor bone loss or response to treatment.
Your doctor decides the timing based on your age, risk factors, and prior results.
What are the important limitations?
DXA measures two-dimensional areal bone mineral density; it does not measure every aspect of bone strength. Arthritis, vertebral compression, calcification, previous surgery, metalwork, positioning, and differences between machines can distort results. Fracture risk must combine the usable DXA sites with age, previous fractures, medicines, falls, medical conditions, and—when appropriate—a validated risk tool.
A fragility fracture can justify an osteoporosis diagnosis or treatment assessment even when the T-score is not in the osteoporosis range. For monitoring, compare valid studies from the same facility and machine where possible, and only call a change real when it exceeds that facility's least significant change (LSC). The timing of another scan should be individualised.
Questions to ask your care team
- Which sites were usable, and did arthritis, fracture, surgery, or metal affect the measurement?
- Should my report be interpreted using T-scores, Z-scores, fracture history, or a risk calculator?
- If this is a repeat study, was it compared with the correct baseline and did the change exceed the facility's LSC?
- Does the result change treatment now, and what clinical reason determines the timing of any repeat DXA?
Sources and further reading
- International Society for Clinical Densitometry: 2023 Adult Official Positions
- RadiologyInfo.org: Bone density scan (DXA)
Conclusion
A DEXA scan is a quick, low-dose, patient-friendly test that helps doctors assess bone strength before fractures happen. It is one of the most useful tools for screening and monitoring osteoporosis and can play an important role in long-term bone health.