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Bone Densitometry

Osteoporosis results from loss of bone mass, leading to bone weakening and increasing the chance of fracture.
A bone densitometry scan is a special type of X-ray test used to measure the calcium content of the bone, usually in the lumbar region (the lower back) and the hips.

General Information

A Bone Densitometry (DEXA – Dual Energy X-Ray Absorptiometry) scan is quick and painless and the preferred procedure for diagnosing osteoporosis.
Using low-dose X-Rays with two distinct energy peaks that are absorbed by soft tissue and bone respectively, a total density value is obtained.
By subtracting the soft tissue density value from this total, the bone mineral density is obtained.
The data is processed on a computer and the bone density measurements are displayed on the monitor.
Two scores are of interest:
- The T score compares one’s bone density to that of a young adult of same gender with peak bone mass. This is used to estimate potential risk of skeletal fractures.
- The Z score compares one’s amount of bone to that of others of same age, size and gender.
Premenopausal women and men under 50 years of age will only be categorised as ‘within normal limits for age’ and not as osteopenic (this refers to bone density that is lower than normal peak density, but not low enough to be classified as osteoporosis or osteoporotic . This is a disease in which the density and quality of bone is reduced. As bones become more porous and fragile, the risk of fracture is significantly increased

Before your BMD examination

It is important to book an appointment.
Please arrive 15 minutes early to complete all the necessary paperwork.
You can also download the patient information form here.
It is very important to bring all previous BMD examination results for comparison purposes
Special preparation:
- Discontinue any calcium supplements for at least 24 hours prior to the examination.
- The study should not be done within 10 to 14 days of any previous barium examination or radiological examination requiring the intravenous administration of contrast (e.g. CT, IVP, MR or Radioisotope Scan).
- No other dietary limitations.

Let the Radiographer know

If there is any possibility that you might be pregnant.
Of any recent intravenous administration of a contrast, or barium study.
Prior lumbar spine or hip surgery or some bone disorders may influence the results and should therefore also be mentioned.
Provide the Radiographer with a detailed medical history, referring specifically to any family history of osteoporosis; medical conditions like diabetes, thyroid, parathyroid, liver or kidney diseases; medications like Prednisone, barbiturates, certain anti-seizure drugs and Eltroxin.
Please bring any previous BMD examination results.

What to expect

The examination will be performed by a trained Radiographer and reported on by a specialist Radiologist.
Any garments with metal zippers, belts or buttons and jewellery may interfere with X-Ray images. You will therefore be required to wear the gown provided.
During the examination, you will lie on a flat, padded examination table while a mechanical arm-like device will pass over your body, emitting low-dose radiation. This procedure is painless.
Regions that enjoy specific attention include the lumbar vertebrae, the femoral necks, and the wrists and forearms.
For best results:
- Cooperation with the Radiographer is essential to the success of the procedure.
- You will have to remain as still as possible throughout the short examination.

After the BMD examination