What is a DEXA scan?
Dual energy x-ray absorptiometry (DEXA) bone density scanning is the most commonly used diagnostic technique for osteoporosis.
As osteoporosis causes no symptoms until a bone is broken, it has traditionally been difficult to identify who may have fragile bones before a fracture occurs. Due to advances in technology and the development of bone densitometry (the measurement of bone density), The lower the bone density, the higher the risk of bone fractures.
Using the DEXA scan we can now detect osteoporosis prior to any bones breaking. This gives individuals who are at a higher risk of fractures the opportunity to take treatments and adopt lifestyle changes in order to reduce their risk of breaking their bones.
Bone density scans are only recommended for people who are considered to be at risk of having a fragility fracture, such as:
- menopausal women (particularly those with an early menopause or following early hysterectomy and removal of the ovaries)
- family history of osteoporosis
- women who have lost their periods with an eating disorder
- women on a steroid therapy
- history of a previous impact fracture.
What happens when one has a scan?
It is a simple, painless procedure that uses very low doses of radiation, which is similar to natural background radiation – less than one tenth of the dosage of a chest x-ray.
A DEXA scan involves lying on a firm couch whilst a scanning arm passes over the body taking an image of the spine and hips.
A DEXA scan will take approximately ten minutes. It is a quick, simple and comfortable procedure.
It does not involve being enclosed in a mechanical tunnel or having any injections.
Usually you will not have to remove any of your clothing, but if there is a significant amount of metal near the hips or along the spinal area, this clothing may have to be removed so it does not affect the scan.
What do the results show?
A DEXA scan produces a printout in which your bone density is compared to a reference range of young healthy adults with average bone density. The difference between this average and your bone density is then calculated and expressed in terms of standard deviations (SD) or difference from the normal value and you are given a T score.
|0 to -0.9 SD||Normal|
|-1 to -2.4 SD||Osteopenia|
|Less than -2.5 SD||Osteoporosis|
Osteopenia is the name for the category between normal bone health and osteoporosis, when bone is less dense than the average but not low enough to be classed as osteoporosis.
Lifestyle changes such as the adoption of a well-balanced, calcium-rich diet and regular weight-bearing exercise are often recommended for people in this category.
If osteoporosis is diagnosed, suitable treatments will be discussed with you.
Should I have further scans in the future to monitor my progress?
The initial scan will help determine if your bone density is too low and whether you require treatment.
If your bone density is not sufficiently low to require treatment, a repeat scan might be performed after one to five years to monitor any further deterioration. Future bone scans will also be performed to monitor response to treatment.
What is the difference between a DEXA scan and an ultrasound?
Ultrasound is an alternative method of investigating the health of other organs in your body., such as imaging the womb, liver, kidney, gallbladder, spleen, ovaries, bladder, breasts and eyes.
It works by generating sound waves of a high frequency, which are beamed into the body. The echoes of the reflected sound, or the rate and path of transmission of the sound, are used to build up an electronic image or measurement of the structure being examined. Ultrasound does not use radiation.