BONE DENSITOMETRY

Bone densitometry measures bone mineral density (BMD) for evaluation of osteoporosis. The commonest technique employs dual-energy x-ray absorptiometry, better known as DEXA and is the accepted gold-standard. Results are accurate and repeatable though false high measurements may occur in patients with severe osteoarthritis.

DEXA assessment of BMD is strongly recommended for the following patients:

• post-menopausal women not taking estrogen supplements
• personal or maternal history of hip fracture, vertebral fracture or other fracture following mild trauma
• tall or thin post-menopausal women and smokers
• those taking corticosteroids, certain anti-convulsants and thyroid-replacement drugs
• sufferers of type 1 (formerly called juvenile or insulin-dependent) diabetes, liver
• disease, kidney disease, hyperthyroidism or a family history of osteoporosis



Test duration is 10 - 30min and radiation dose is negligible. Nevertheless patients must inform their doctor an radiographer about possible pregnancy. Results consist of statistical "T" and "Z" scores:

• T score — This number shows the amount of bone you have compared to a young adult of the same gender with 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. It is used to estimate your risk of developing a fracture.
• Z score — This number reflects the amount of bone you have 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