Bone Density

Bone mineral density is a measure of how strong a person’s bones are. Bones begin to form before birth and continue to increase in density until about 30 years of age. Most bone growth happens during the first 20 years.

Bone density measurement

The most common way to measure bone density is by using dual-energy x-ray absorptiometry or DEXA. This is a simple technique using low intensity x-rays with two different peaks. One is absorbed by the soft tissue and the other by the bone. By comparing the two, a measurement of bone density is obtained.

Many clinics and drug stores have a portable DEXA instrument for peripheral measurements usually the wrist or heel. Hip and spine scans available in hospitals are usually considered more reliable for accurate detection.

Results of bone density measurement

A T score is calculated from the data gathered by the machine. These scores mean:

• A score above -1 is in the normal range
• A score between -1 and -2.5 is defined as osteopenia (low bone density)
• A score below -2.5 is defined as osteoporosis