Best way to diagnose Osteoporosis

Unexplained fracture of wrist or hip joint,back ache,stooping of the shoulders are generally taken as symptoms of Osteoporosis.But how is it diagnosed?
 A basic test by the name of Bone Mineral Density (BMD) test is employed to establish Osteoporosis and find out if the person is suffering from low bone mass.BMD can be tested in different ways such as ultrasound , quantitative computed tomography (QCT) and  Dexa-Scan(dual-energy X-ray absorptiometry or DXA).Out of these Dexa -Scan is the most popular method and considered to be giving most accurate results.
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