Osteoporosis screening with DEXA

What it is

A DEXA scan is the test used to screen for osteoporosis. Osteoporosis itself is a loss of bone mass, present when bone mineral density lies more than 2.5 standard deviations below the young adult mean density.

The scan gives two: 1) the T-score, based on the bone mass of a young reference population, a comparison with a young adult at peak bone density; 2) the Z-score, adjusted for age, gender and ethnic factors, so it compares a person with others of the same age. A second definition runs alongside: osteoporosis is a systemic skeletal disease characterized by diminished bone strength with the risk of sustaining a fracture when falling from own body height, a fragility fracture. Three types are named, post-menopausal, age-related and secondary. 13%-18% of white American women aged 50 and over have osteoporosis of the hip, and lower estrogen levels account for about 2/3 of bone loss during the 5-7 years around menopause. The scan itself has two types: central DEXA of the lumbar spine, hip and whole body, and peripheral DEXA of the forearm and calcaneum.