DXA / DEXA / Osteodensitometry

Dual-Energy X-ray Absorptiometry (DXA) is a reliable method for measuring bone density. This non-invasive test helps to assess the risk of osteoporosis and other bone diseases as well as to accurately determine body composition. DXA is often used to monitor bone health in individuals at risk of bone loss, providing a basis for prevention and treatment of this condition. It can also be used to accurately measure body composition, fat and muscle distribution, amount of visceral fat and symmetry of the musculoskeletal system.

Medical experts believe that DXA scans are the most useful, simple and inexpensive tests to help diagnose osteoporosis. The test is quick and painless.

What is osteoporosis?

Osteoporosis is a term used to describe brittle bones and the risk of bone fractures. With age, bones can lose thickness and strength. Osteoporosis literally means “porous bone”. DXA tests help your health care provider monitor bone density and risk of bone fractures over time.

Osteoporosis occurs when you lose bone faster than your body can make new bone tissue. It is most common in postmenopausal women. Over time, bones become weaker. Of course, fragile bones break more easily.

Health professionals sometimes call osteoporosis a “silent” disease because it doesn’t hurt. Many people first realize they have osteoporosis after breaking a bone in a fall.

What is osteopenia?

Osteopenia is a term used to describe “low bone tissue”. Many individuals, including those who are slim and very active, have lower bone density throughout their lives. However, this does not necessarily mean that they will develop osteoporosis. Many top athletes have low bone density, but their bones are healthy and very strong. Osteopenia is not “pre-osteoporosis,” but sometimes, if a person has other risk factors for fracture, osteoporosis therapy may be recommended to prevent future fractures.

What does a DXA scan look like?

DXA scans measure the mineral content of certain bones, such as the hip, spine and/or forearm. The procedure is as follows:

You will be asked to lie on a special DXA table. The technician will help you position yourself correctly and will use aids such as sponges to maintain the desired position. As the arc of the DXA machine passes over the body, it uses two different x-rays. The rays use very little radiation to make the test safer and help distinguish bone from other tissues. The scanner translates bone density measurement data into images and graphs. These results are then printed and you can show them to your doctor, usually the referring endocrinologist or rheumatologist.

Who should do a DXA scan?

Healthcare professionals consider many factors when deciding who might benefit from a DXA scan and how often. Healthcare professionals often recommend a DXA scan to assess bone health and fracture risk due to osteoporosis if you are over 50, have a broken bone, or other diseases that threaten your bones.

Research shows that women start losing bone mass earlier and faster than men. Therefore, health professionals usually recommend that women have a DXA scan to screen for osteoporosis at a younger age compared to men.

Your healthcare provider may recommend a DXA scan if you have one or more risk factors for osteoporosis or fractures:

Increased age: Most people lose bone mass as they age.

Family history: If one or more family members have osteoporosis or more than one fracture, you may be at greater risk of bone loss.

Previous fractures: Broken bones, especially after age 50, can be a sign that you are at higher risk. Porous (less dense) bones break more easily.

Medications: Some medications, such as the steroid prednisone, some cancer medications, and medications used after organ transplants can weaken your bones.

Your general health: Many chronic medical conditions can increase the likelihood of bone fractures. Risk conditions include rheumatoid arthritis, lupus, diabetes, liver disease and kidney disease.

What else do healthcare professionals use DXA for?

Healthcare providers may request a DXA scan to:

Tracked changes in bone health over time. Monitor your response to therapy. Assess body composition, such as the amount of fat and muscle tissue in your body (and where it is).

How often should a DXA scan be done?

Your healthcare provider will consider several factors, such as your age, level of fracture risk, previous DXA results, and current medications. Then, your healthcare provider will create a personalized plan to assess and protect your bone health.

How to prepare for a DXA scan?

Most people do not need to change their daily routine before a DXA scan. Eat, drink and take your medicine as usual, unless your healthcare provider tells you otherwise.

Before the test, please do the following:

Stop taking calcium supplements 24 hours before the test: This includes multivitamins as well as antacids that are often used to treat heartburn. Wear comfortable clothes. Try to choose clothes that do not have metal (threads, buttons, buckles…). Tell your doctor if you might be pregnant: DXA scans use low levels of radiation. Doctors recommend avoiding all radiation exposure during pregnancy.

How long does a DXA scan take?

DXA imaging for osteoporosis (hip + spine) takes about 10 minutes, while imaging for body composition (body composition) takes about 15 minutes, together if they are done about 25 minutes.

Is a DXA scan painful?

Not. You won’t feel anything while lying on the table

How accurate is a DXA scan?

DXA examinations provide a high degree of precision and accuracy. Medical experts consider DXA examinations to be the gold standard for the diagnosis of osteoporosis.

Unlike x-ray machines, DXA machines are sensitive and calibrated daily to determine their ability to accurately measure bone mineral, and no two DXA machines are exactly the same. This is why your doctor will insist that you do all DXA tests on the same machine.