A bone mineral density test is the typical way of diagnosing osteoporosis and predicting your risk of fractures. It's a kind of X-ray that reveals the hardness of your bones. The most common type is called a dual-energy x-ray absorptiometry (DEXA or sometimes called DXA.) Usually, the scans look at the weight-bearing ability of your hip and spine, then uses this information to estimate your risk of fractures.
After the test, your doctor will work out your "T-score." This indicates how dense your bones are compared to those of younger, healthy women. Usually, a T-score defines your score as being above or below the norm.
A normal bone density is a T-score of plus one (+1) to a score of a minus one (-1). A low bone mass (osteopenia) is a bone density T-score of -1 to -2.5. Osteoporosis is defined as a bone density score of -2.5 or below.