<prompt> Osteoporosis in postmenopausal women is defined by T-score of1 to 2.5 SD0 to -1 SD-1 to -2.5 SDBelow -2.5 SD  <response>: T Score: Standard detions between patient and average peak young adult bone mass. The more negative, the greater the risk of fracture. Z Score: Standard detions between patient and average bone mass for the same sex, age, and weight. A Z score lower than -2.0 2.5 of the normal population of the same age requires diagnostic evaluation for causes other than postmenopausal bone loss.The clinical relevance of a bone density measurement in a postmenopausal woman is estimated by using the T Score. For younger women, interpretation utilizes the Z ScoreDefinitions Based on Bone Mineral DensityNormal: 0 to -1 SD from the T-score reference standard 84 of the population Osteopenia: T-score -1 to -2.5 SD Osteoporosis: T-score below -2.5 SDReference: Clinical Gynecologic Endocrinology; 8th edition; Chapter17; Menopause and the Perimenopausal Transition 