DEXA Scan (Bone Density Test):what to expect

Your doctor may request a DEXA scan to:

• Check for osteopenia or osteoporosis
• Evaluate fracture risk
• Follow known low bone density over time
• Monitor the effect of osteoporosis treatment
• Assess bone health in people with risk factors such as age, menopause, steroid use, or certain chronic illnesses

A DEXA scan measures bone mineral density. In simple terms, it helps show how much mineral is packed into your bones and gives doctors an estimate of how strong those bones are.

The scan does not diagnose every possible bone problem, but it is very useful for identifying thinning bones and fracture risk.

Most standard DEXA scans assess:

• The lower spine
• One or both hips

Sometimes the forearm is assessed if the usual sites cannot be measured properly or if there is a specific clinical reason.

No. A DEXA scan is painless and noninvasive. There are no injections and no special recovery time afterward.

These are ways of interpreting the result:

• A T-score compares your bone density with that of a healthy young adult and is commonly used in adults for osteoporosis assessment.
• A Z-score compares your bone density with others of a similar age or stage of life and may be more helpful in some patients, especially younger people.

Your doctor will explain which score applies to you and what the result means in practical terms.

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.

Preparation is usually minimal.

Your imaging center may ask you to:

• Avoid calcium supplements for a period before the exam, often 24 hours
• Wear clothes without metal zips, belts, or buttons around the scan area
• Inform the team if you recently had a barium study or a contrast/tracer-based imaging test
• Mention possible pregnancy before the scan

Yes, in most cases you can eat and drink normally before the scan unless your center gives different instructions.

During the test:

• You lie on a padded table
• The Radiographer positions you carefully
• A scanning arm passes over the part of the body being assessed
• You stay still while the machine takes measurements

The scan is open and does not involve a tunnel like MRI. Most people find it very easy to tolerate.

The imaging itself is usually quick, often around 10 to 20 minutes. The full visit may take a little longer depending on check-in and positioning.

A radiologist or another qualified clinician reviews the study and reports the bone density results. Your doctor will then explain whether your bones are within the expected range, mildly low, or in a range suggesting osteoporosis.

For most people, yes. It uses a very low dose of radiation and is generally considered a safe test when medically indicated.

Even though the dose is low, it is still an X-ray-based examination, so pregnancy should always be mentioned before the scan.

Yes, when medically needed. In children and adolescents, DEXA may be used in selected cases to assess bone health, but interpretation is different from that in adults. Pediatric results need to be read in the right age and growth context.

• International Society for Clinical Densitometry: 2023 Adult Official Positions
• RadiologyInfo.org: Bone density scan (DXA)

A DEXA scan is a simple but very useful test for measuring bone density and estimating fracture risk. It is low dose, painless, and easy to tolerate, and it plays a major role in screening for osteoporosis and monitoring long-term bone health.