What is a DEXA scan?

Posted in , by Echelon Health

What is a DEXA scan?

A DEXA scan — or dual-energy X-ray absorptiometry — is also known as a bone density scan. It is a medical imaging test that is used to measure the bones’ mineral content in certain parts of the body. The DEXA scan is carried out by transmitting low dose x-rays usually in the hips and lower spine.

DEXA scans use high precision, low level X-rays to measure bone density and track bone loss. They are often considered the best test for the diagnosis of osteoporosis; a disease that weakens the bones and can put you at greater risk of bone fractures. If you have an abnormally low bone density, this indicates an osteoporosis risk.

How does a DEXA scan work?

DEXA scans are completely non-invasive and do not require an injection. You won’t be asked to go inside a ‘tunnel’ – rather, you’ll lie flat on your back on an open X-ray table. At Echelon Health, your DEXA scan will be carried out by a highly experienced radiographer who specialises in taking X-ray images.

You will be asked to keep as still as possible during the procedure, to avoid blurring the images. A large scanning arm is passed slowly over your body, measuring the bone density in the skeleton. The area of your body targeted for examination will be passed through by a narrow, low-dose X-ray beam. It might be that more than one part of your body is scanned, as bone density differs in the various parts of the skeleton. 

Inside the scanning arm there is an X-ray detector. This measures the number of X-rays that have been passed through the body, and this information is used in the production of imagery of the scanned area. Once the test is complete you will be able to resume your normal daily activities.

What does a DEXA scan show?

The results of a DEXA scan allow a measurement of bone density to be recorded. They will be read by a radiologist before being passed to you and your doctor. By comparing your bone density with the bone density of a healthy adult of a similar age, gender and ethnicity to you, the results of a DEXA scan feed into a scoring system that can show the difference between your own bone density and the expected score. 

This calculation is known as the standard deviation (SD) score. You can read more about this scoring system in the ‘DEXA scan results’ section further down this page.

How long does a DEXA scan take?

A DEXA scan takes just a few minutes – usually 10 to 20. There is no recovery time associated with a DEXA scan, meaning that once the test is completed, you will be free to go and resume your daily activities.

DEXA scan side effects

Not only is a DEXA scan quick, but it is also completely painless. You will rarely experience any short term side effects from a DEXA scan. They use a far lower level of radiation than normal X-rays.

DEXA scan results

Let’s return to the scoring system for DEXA scan results. 

‘T score’ is the difference between your measurement and the expected score of a young healthy adult. 

‘Z score’ is the difference between your measurement and the expected score of a healthy adult in a similar demographic to you. 

A Z score that is below -2 indicates lower bone density than normal for a person of your age. A Z score which is -2.5 or lower indicates that you may have osteoporosis.

While a DEXA scan can provide results that are an accurate indicator of bone strength, they are not necessarily an indicator of whether you will suffer a bone fracture. Somebody with a low bone density score might never get a bone fracture, while somebody with a normal bone density score could get several fractures. That’s due to a range of other factors – including if you’ve previously been injured, your age and your gender – that can also determine whether you have a high risk of experiencing a fracture.

Your doctor will look through the DEXA scan results with you, discuss whether you require treatment, and if so, what the best treatment options are. In some cases, a second scan could be needed in the future to track any changes. So now we have explained how a DEXA scan can indicate osteoporosis, let’s look closer at the condition itself.

What is osteoporosis and how can I treat it?

Osteoporosis is a bone disease that occurs when the body loses too much bone, produces too little bone, or both. In some cases, the bones can become so brittle that coughing or stretching may cause a fracture. The most common osteoporosis fractures occur in the hip, spine, or wrist. Because bone is made of living tissue, it is continually breaking down and being replaced.

While both men and women of all ethnicities can get osteoporosis, it is understood that older white and Asian women are at a higher risk. Bone structure, body weight and family history are other potential risk factors for osteoporosis.

Osteoporosis can be known as a ‘silent disease’ – symptoms, especially in the early stages, are rare. However, potential early stage indicators could be:

  • A weaker grip
  • Receding gums
  • Brittle fingernails

As the condition develops, other symptoms could include: 

  • Back pain, caused by a fractured or collapsed vertebra
  • Loss of height over time
  • A stooped posture
  • A bone that breaks much more easily than expected

On many occasions, osteoporosis is not discovered until weakened bones cause painful fractures usually in the back or hips. Unfortunately, once you have a broken bone due to osteoporosis, you are at high risk of breaking another. Fortunately, there are steps you can take to help prevent osteoporosis like maintaining a healthy intake of calcium and vitamin D rich foods and regularly undergoing a DEXA or BMD scan to ensure the health of your bones.

Osteoporosis is likely to be diagnosed via a DEXA scan. Treatment options can then be recommended depending on the results of this test. The main form of treatment for osteoporosis is medication, of which there are various classes. The medication recommended to you will vary according to your individual requirements. 

When should I get a DEXA scan?

Unfortunately, osteoporosis can cause premature death, so it is important, like all diseases, to catch it early. Bone density starts to deteriorate approximately by your late 30’s. Depending on your age, a DEXA scan is essential every 2 to 15 years.

If you think you may be experiencing some early stage osteoporosis symptoms, or would like your risk of developing the condition to be assessed, book a DEXA scan at Echelon Health (you can see our range of private health assessments here). 

Our world class team of radiologists and doctors make use of the most advanced medical imaging technology available, meaning you are in the best hands. Call us today on +44 (0)20 7580 7688 to find out more.