Densitometric measurement of bone mass has become central to the diagnosis of osteoporosis and decisions about treatment to prevent fracture. BMD measurements are used to establish a diagnosis of postmenopausal osteoporosis; determine fracture risk; identify candidates for intervention; and assess changes in bone mass over time in both treated and untreated patients.³ BMD is expressed as a T-score, which is the number of standard deviations above or below the mean for a young adult healthy population. Dual x-ray absorptiometry (DXA) of the hip is the gold standard for the diagnosis of osteoporosis using the WHO criteria. Central measurements of BMD with DXA are used to determine baseline BMD for follow-up measurements. Dual x-ray absorptiometry (DXA) of the hip and spine is the gold standard for baseline BMD determination and follow-up measurements. Other techniques include quantitative computed tomography (QCT), ultrasonography, single-energy x-ray absorptiometry (SXA), and radiographic absorptiometry. Common central skeletal sites for measurement include the spine and hip; peripheral sites include the forearm, wrist and heel.