What is Endocrinology - What categories do doctors use to diagnose bone mass?

What is Endocrinology - What categories do doctors use to diagnose bone mass?
​Using T-scores derived from DXA BMD measurements taken from the spine, hip, or forearm, the World Health Organization (WHO) published criteria for the diagnosis of osteoporosis and osteopenia in postmenopausal white women and older men in 1994. Normal BMD is defined as a T-score greater than 21.0, low BMD (also known as osteopenia) is defined as a T-score between 21.0 and 22.5, and osteoporosis is defined as a T-score less than 22.5. A T-score of under 22.5 and the occurrence of one or more osteoporotic fractures are considered indicators of established (or severe) osteoporosis.