Definitive diagnosis of osteoporosis relies on the use of dual-energy
x-ray absorptiometry (DXA) - in New Zealand, access
to funding for drugs to manage osteoporosis requires
documentation of bone density via DXA.12
DXA involves the use of very low-dose x-rays to
assess bone density in the hip and the spine. This density
is then compared, via an algorithm, to the mean
bone density seen in healthy younger adult women.
Current data for this comparison is largely based on
premenopausal white women, so results may not be
accurate for other ethnicities, children or men.13
Comparison with "normal" bone density allows the
generation of a T-score — a value that states how far
from the normal a person's result is. A diagnosis of
osteoporosis is made if the T-score is -2.5 or more.
However the risk of having a fragility fracture is not
solely correlated to DXA result.