A DXA scan is a low-dose radiation test to measure the strength of your bones. It can also be used to assess the amount of muscle and fat in your body.
The scan checks bone health for osteoporosis, which would increase the risk of fracture (break) of a bone. This scan involves radiation to the hips and spine, and sometimes to the wrist. DXA may also tell the amount of fat, muscle and bone in certain medical conditions, or to track fitness over time. This is a full body scan, and would need to be requested by the referring doctor. DXA uses a very small amount of radiation and is safe to have repeated yearly, or as deemed necessary, to monitor bone density, especially if on treatment for osteoporosis.
How to Prepare for Your DXA Scan
Preparation for a DXA scan is very straightforward:
- Wear loose clothes,
- don’t have any metal on you (accessories, on your clothes, etc.),
- have an empty bladder,
- and do not take calcium tablets on the day of the scan.
For a full body scan, you would be asked to not exercise for 24 hours, empty your bladder, and eat a very light meal the day of the scan, for accurate results.
The scan lasts up to 20 minutes, is painless, and is not invasive. You lie on your back, and the arm of the machine passes over you, without touching you. The Technologist will lie you in the right position, and will lift your legs onto a block when measuring the hips. To check the side view of the spine, to help diagnose fractures, she will ask you to lie on your left side if possible.
What Do the Results Mean?
Results are issued to your referring doctor within a week, having been reported by one of our Physicians.
Scans are reported as T-score:
- Normal: T-score of above -1.0, with no treatment needed other than maybe some lifestyle changes such as increasing exercise, especially resistance (weight or resistance bands) exercises, reducing alcohol intake, stopping smoking, and eating foods rich in Calcium and Vitamin D, or taking a Calcium/Vitamin D supplement if needed.
- Low Bone Density: This is a T-score of -1.1 to -2.4. Advice will be as above, but also to reduce the risk of falls by strengthening leg muscles and balance exercises. You may also be prescribed medication if you have had previous fractures or if you are at high risk.
- Osteoporosis: This is when the T-score is at or below -2.5. In this situation, medication will be recommended, either in tablet form or as an injection, as well as all the above advice.
Or As Z-score:
- A Z-score of above -2.0 is within the acceptable range for age and sex.
- A Z-score of -2.0 or less indicates that the bone density is lower than expected for age and sex, and
advice from the referring doctor is strongly advised.
Ongoing Monitoring and Follow-Up
With a Low Bone Density or Osteoporosis diagnosis, DXA scans should be repeated regularly, either every 12–18 months in the case of osteoporosis, or every 2–3 years for low bone density. These repeat scan intervals will be recommended by the reporting and/or treating Physicians. To monitor changes in bone density, it is best practice to repeat the scan on the same scanner each time to accurately assess the interval changes.
