Uncertainties in bone mineral density T scores.
In the diagnosis and management of osteopenia and osteoporosis, dual photon absorptiometric measurements of lumbar spine and proximal femur bone mineral density are interpreted by calculating a T score, which is the number of standard deviations by which a result deviates from the mean bone density in young adults of the same sex. Threshold values are then used to categorize patients as having osteopenia or osteoporosis. The uncertainty associated with a single bone mineral density measurement, as well as the uncertainties in the assumed values for the bone mineral density in young adults and the population standard deviation, combine to create an uncertainty in the calculated T score. It is estimated that 95% of bone density measurements have a T score uncertainty of less than 0.4. This means that a single measurement of bone mineral density should not be used in isolation to assign a given patient to a specific diagnostic category. Rather, a bone mineral density measurement should be regarded as only one of the variables that determine the risk of fracture in a given patient.
Webber
C E
CE
Department of Nuclear Medicine, Hamilton Health Sciences Corporation, Ont.
D015502:Absorptiometry, Photon; D000328:Adult; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000175:diagnosis; D006801:Humans; D010024:Osteoporosis / Q000175:diagnosis; D012016:Reference Values; D012680:Sensitivity and Specificity