The Facts

• According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, BMD tests can detect cases of osteoporosis, measure an individual's response to osteoporosis treatment and predict the likelihood of bone fractures.
  
  

Testing Principles

• BMD tests measure the mineral content in a bone's interior. As a rule, high mineral content in a bone indicates high bone strength, while low mineral content indicates low bone strength, according to the Mayo Clinic.
  
  

Measuring Bone Mass

• Typically, BMD tests compare an individual's bone mass to that of a hypothetical, healthy 30-year-old. Doctors measure the differences between these two readings in units called standard deviations (SDs), according to the National Osteoporosis Foundation.
  
  

Results

• Individuals within one SD of the norm have normal bone mass. Those between one and 2.5 SDs have clinical low bone mass. Those in excess of 2.5 SDs have osteoporosis.
  
  

Additional Measurements

• Your doctor may also measure your bone mass against others in the same age group to detect any underlying diseases related to your bone loss.