Bone Density Test (DEXA)
A bone density test, also called dual-energy x-ray absorptiometry (DEXA) is a quick and noninvasive method for diagnosing osteopenia and osteoporosis (loss of bone density). A low dose ionizing radiation is used to calculate the density of bone and thus the amount of bone loss. Usually the density of the hips and lumbar spine is obtained, but if you had a hip replacements or posterior lumbar spinal fusion with pedicle screws in the back, bone density cannot be done in these areas. In these cases, bone density of the wrist will be done.
In post-menopausal women and men older than 50 years, a T-score is calculated. This is a comparison by standard deviation (SD) to a young adult population matched for sex and ethnicity. In pre-menopausal women and men younger than 50 years, a Z-score is calculated – compared by SD to an age, sex and ethnicity.
As with all other studies, you will need your referral letter, ID and medical aid card. The reception staff will help you with medical aid approval if needed. It is advisable to phone in advance to confirm a date and time.
On arrival you will be asked to undress and put on a radiology dress. This is to remove any additional density from clothing such as belts, zippers ext. to get an accurate measurement. As mentioned before, this is a noninvasive examination. You will have to be able to keep still for a few minutes whilst lying on your back.
A bone density test should not be performed if you are pregnant.