Bone Densitometry

DXA (Dual energy x-ray absorptiometry) uses a very low amount of x-ray energy to assess a patient’s bone density levels. It is a painless, non-invasive procedure. No needles, no contrast agents, and just a few preparations are necessary in order to have the test.

Why should I have a bone density (DXA) study?
Throughout life our bones are continuously changing. They go through cycles of bone loss and the formation of new bone. Osteoporosis occurs when these cycles are no longer in balance with each other. In other words when the breakdown of bone (osteoclast activity) occurs at a faster rate than the rebuilding of new bone (osteoblast production).

Osteoporosis is a disease that causes bone to become brittle, thin and therefore may enable someone to be at greater risk for a fracture. This process can take years to occur and the majority of individuals may never have any sign or symptoms of the progression of bone loss until a fracture occurs. Tiny micro fractures may be happening in the spine (backbone) that does not cause any serious onset of symptoms. Only with significant collapse of a vertebral body will a patient experience severe back pain. At this time the damage from osteoporosis has already begun. If osteoporosis is allowed to progress, you can lose several inches in height and your back can become hunched over (kyphotic). At this time you are at greater risk for future fractures in the spine, hip and wrist. Minor trauma may cause these fractures to occur. The most important fact is that early detection can prevent excessive bone loss and therefore prevent fractures from happening.

When should a bone density study be considered?

• Women who are postmenopausal. It has been documented that the greatest bone loss for women can occur within five years following menopause.
• Women who have gone through premature menopause.
• Men or women on long term steroid, anticonvulsant and thyroid medication.
• Men, women or children with chronic diseases, which require therapies that can affect, bone metabolism.
• Men, women or children with anorexia nervosa.
• Children with growth disorders, metabolic diseases, delayed puberty, malnutrition.

What must I do in order to prepare for the exam?

• We asked that you do not wear any clothing with buttons, snaps or zippers. If you do not have any available, we will provide you with a gown.
• Calcium supplementations should not be taken the morning of the exam.
• Please advise us if you have had a recent diagnostic study involving oral contrast agents (i.e. CT scan utilizing barium contrast). It is very important to wait at least 10 days before having the DXA scan because residual barium in the colon will interfere with the results.
• Please inform us prior to the exam if you think you may be pregnant.

What should I expect?
During the procedure you will be lying on a soft padded table on your back. The scanner will make a sweeping motion over your lower back and then the unit will scan both of your hips. The data acquired will than be analyzed and evaluated by a Radiologist.

What do the results mean?
There are two grading values for bone density assessment. The Z-score (age-matched) and the T-score.

If a patient is under age 50 and not yet postmenopausal the Z-score (age-matched) is utilized for bone density assessment. The Z-score will compare a patient to someone of the same age and sex.

If a patient is over age 50 and/or postmenopausal the T-score is utilized for bone density assessment. The T-score is comparing a patient to a normal young adult at peak bone mass. Therefore, the study evaluates how a patient’s values deviate from the optimal bone mass of a 25 to 30 year old individual.

Low bone mineral density increases your risk for fracture. Therefore, it is important for you to have a baseline bone density test in order for your physician to be able to monitor your rate of bone loss and if necessary your response to therapy. Follow-up bone density studies are recommended every two to three years depending on your baseline values and risk factors for bone loss.
How do I schedule a DXA scan?

You must contact you physician and discuss your concerns regarding having a bone density study. Your Doctor will determine if your medical history warrants having a bone density study and will give you an order to have the procedure completed.