Bone densitometry, or DEXA (Dual-Energy X-ray Absorptiometry), is a simple, non-invasive X-ray procedure that is used to measure bone mineral density. The results may help reduce your risk of developing bone loss, osteoporosis or a fracture.
The procedure is painless and radiation exposure is minimal. At the same time as bone density assessment, if requested we can also analyse your body fat composition and estimate your lean muscle mass.
A Bone Density Scan is recommended if you:
- Are a post-menopausal woman and not taking hormone replacement therapy
- Are a man over 65 years old, or if you are on androgen deprivation therapy (e.g. for prostate cancer)
- Have a history of smoking
- Have experienced bone loss or bone trauma
- Have a family history of osteoporosis, fracture(s), hyperthyroidism and other related clinical conditions such as diabetes, liver or kidney disease
- Use certain medications known to contribute to bone loss as a side effect such as corticosteroids, prednisone, some barbiturates or thyroid replacement medications
How is a DEXA Scan performed?
You will be asked to lie on the examination table for a short time while the arm of the machine passes over your body taking measurements. It will be important that you stay as still as possible during the procedure to ensure a clear, useful image. Our radiologist will interpret the results of your DEXA scan and provide a report for your doctor. DEXA reports are given with two scores — a "T" score and a "Z" score.
- "T" score indicates the amount of bone you have when compared with a young adult of the same gender with a peak bone mass. A score above -1 is considered normal. A score between -1 and -2.5 is classified as osteopenia, the first stage of bone loss. A score below -2.5 is defined as osteoporosis, and may be used to estimate your risk of developing a fracture.
- "Z" score indicates the amount of bone you have when compared to other people in your age group and of the same size and gender. If it is unusually high or low, it may indicate a need for further medical tests
How do I prepare for a DEXA scan?
There is little or no preparation for a DEXA scan. You should eat as you normally do; however, it is recommended that you do not take any calcium supplements 24 hours prior to the exam. These can lead to erroneous results and you may be asked to return for a repeat scan.
You may have to wait 10-14 days before undergoing a DEXA test if you have had another diagnostic study that required the use of a contrast agent (such as a barium enema, an upper/lower GI series), or have been injected with a contrast material (for a computerised tomography (CT) scan, a radioisotope scan or PET/CT scan).
As with all radiological procedures, prior to commencing the scan you should inform the technologist if there is any chance you may be pregnant.
