Bone Densitometry

Bone mineral density (BMD) is a predictor of fracture risk and should be assessed using dual-energy X-ray absorptiometry (DXA), ideally at two sites: the anteroposterior spine and hip. In older adults, degenerative changes in the spine may result in artificially elevated BMD readings; hence, DXA of the hip is generally more reliable for accurate assessment.

Bone densitometry using DXA helps identify osteoporosis and osteopenia, guiding timely intervention. For fragility fracture patients treatment must not be delayed if DXA is unavailable.

BMD results are reported as either a T-score or Z-score. The T-score compares the patient’s BMD to that of a healthy young adult, with a score of ≤-2.5 indicating osteoporosis and a score between -1 and -2.5 indicating osteopenia. The Z-score compares the patient’s BMD to age-matched controls.

Osteopenia serves as an early indicator of bone loss, highlighting the need for timely intervention to prevent progression to osteoporosis, particularly in patients with a history of fragility fractures or multiple risk factors.

For individuals suspected of having osteoporosis or osteopenia, establishing a baseline BMD informs future management decisions. Indications for BMD testing include:

• Fragility fractures
• Women under 65 years with osteoporosis risk factors
• Women aged 65 and older, and men aged 75 and older, considering osteoporosis prevention measures
• Patients on glucocorticoids for more than six months

If DXA scanning is unavailable, fracture risk can still be assessed using the FRAX® or Garvan fracture risk calculators without a BMD value. For patients aged 75 and older with a radiologically confirmed fragility fracture, BMD assessment may not be necessary for accessing PHARMAC-funded medications. Although DXA is recommended after a fragility fracture occurs, treatment must not be delayed if DXA is unavailable.