DEXA is the gold standard for measuring bone density. According to criteria established by the World Health Organization, normal bone density is reflected by a T score of +1.0 to -1.0, which is a value within 1 standard deviation (SD) of the young adult mean. Osteopenia is diagnosed by a T score of -1.0 to -2.5, which is a value greater than 1 SD below the young adult mean, but less than 2.5 SDs below this value. Osteoporosis is diagnosed by a T score of -2.5 or less, which is a value 2.5 SDs or more below the young adult mean.
