Bone Densitometry (DEXA Scan)

A DEXA scan (Dual-Energy X-ray Absorptiometry) is a quick, painless imaging test that measures how dense and strong your bones are.

The scanner sends two low-dose X-ray beams through your body, usually aimed at your spine and hips. Different tissues absorb these beams differently. The machine compares how much energy passes through the bone versus how much is blocked, then calculates a bone mineral density (BMD) score — a measure of how much calcium and mineral is packed into your bone. This score tells your doctor whether your bones are healthy, thinning (a stage called osteopenia), or significantly weakened (a condition called osteoporosis).

A DEXA scan is ordered when a doctor wants to assess bone strength, monitor how bones change over time, or check whether a treatment for bone loss is working.

• Suspected osteoporosis (significant thinning of bone that raises fracture risk)
• Osteopenia (early-stage bone thinning detected before it becomes osteoporosis)
• Women who have gone through menopause, especially if they have additional risk factors
• Men over 70 or women over 65 as part of routine bone health screening
• Long-term use of corticosteroids (steroid medicines that can weaken bone over time)
• A fragility fracture — a broken bone that happened from a minor fall or everyday activity
• Conditions that affect calcium absorption, such as coeliac disease (a gut condition) or chronic kidney disease
• Monitoring the effectiveness of treatment for osteoporosis or other bone-weakening conditions
• Low body weight or a history of eating disorders, which raise the risk of weak bones
• Family history of hip fracture or osteoporosis

There are a few situations where a DEXA scan is not the most suitable choice or needs to be adapted.

• Pregnancy — X-ray exposure, even at low doses, is avoided during pregnancy
• Recent barium contrast imaging or nuclear medicine scan (residual contrast material can distort readings)
• Severe obesity in some cases, as body size can affect the accuracy of the scan on standard machines
• Patients who have already had multiple DEXA scans in a short period may not need another one yet — your doctor will advise the appropriate interval

A DEXA scan is one of the safest imaging tests available, and for most people the risks are very small.

• Low radiation exposure — the dose is very small, far lower than a standard chest X-ray, and considered negligible for most adults
• Radiation is not suitable during pregnancy, so the scan is postponed if pregnancy is confirmed or suspected
• Rarely, residual contrast material from a recent scan of another type can affect the accuracy of the result, leading to the need for a repeat scan
• The scan itself causes no pain, no injection, and no skin contact with any instrument — there is no wound and no recovery period

Preparation for a DEXA scan is minimal compared with many other medical tests. There is no need to fast beforehand, and most people can eat and drink normally on the day of the scan.

Before the scan, your care team will usually ask about the following:

• Calcium supplements — doctors usually advise stopping them for at least 24 hours before the scan, as they can affect the reading
• Recent imaging tests — tell the team if you have had a barium X-ray, CT scan with contrast, or a nuclear medicine scan in the past few days
• Pregnancy — you will be asked whether you are or might be pregnant
• Metal implants or devices — inform the team of any metal in your body, such as joint replacements or spinal rods, as these can affect the scan in that area

No special blood tests or imaging are routinely needed just to prepare for a DEXA scan. However, your doctor may have already ordered blood tests to check calcium and vitamin D levels as part of the wider investigation.

Here is what typically happens during the scan itself:

• You will be asked to wear comfortable, loose clothing without metal zips, buckles, or buttons in the area being scanned — or you may be given a gown
• You lie flat on a padded table; no tunnel or enclosed space is involved
• The scanning arm moves slowly over your body, usually focusing on the lower spine and one or both hips
• You are asked to stay still and breathe normally — no breath-holding is required
• The whole procedure usually takes around 10 to 30 minutes, though timing varies between machines and how many body areas are scanned
• You can leave immediately afterward; no observation period is needed

Because a DEXA scan is non-invasive (nothing enters the body), there is no physical recovery needed afterward. You can return to your normal daily activities, diet, and any regular medicines immediately. The aftercare focus is on understanding your results and acting on them with your doctor's guidance.

• Results are usually interpreted by a radiologist (an imaging specialist) and sent to the referring doctor, who will explain what your bone density score means for you personally
• If your score indicates osteopenia or osteoporosis, your doctor will discuss options such as lifestyle changes, dietary adjustments, or treatment — the right plan depends on your overall health and other test results
• If you are already on treatment for bone loss, follow-up scans are usually scheduled at intervals determined by your doctor to track whether the treatment is helping
• Lifestyle factors that support bone health — such as weight-bearing exercise, adequate calcium and vitamin D intake through food, reducing alcohol, and not smoking — are commonly discussed at your follow-up appointment
• If you have any questions about your results or what they mean for your fracture risk, write them down before your follow-up appointment so you can discuss them fully with your doctor