DXA Measures Bone DENSITY?? Apparently Not.

[Guest guest]

Hi folks:

According to this quote from the NIH osteoporosis page, it would

appear that only QCT scanners actually measure the DENSITY of bone.

DXA, I presume, then, measures bone MASS?

" Unlike DXA, QCT can determine the actual volumetric density of bone

irrespective of bone size and can distinguish between cortical and

trabecular bone tissue " :

http://www.osteo.org/newfile.asp?

doc=n402 & doctype=HTML+Newsletter & doctitle=Assessment+of+Bone+Mineral+D

ensity+and+Fracture+Risk

http://snipurl.com/dvqj

If this is correct (presumably the NIH is not wrong) then those with

a low BMI and bone mass to match, will be diagnosed, when compared

with people with a BMI of ~29.3, as having low bone DENSITY - whether

they have or not.

I have still not found a source that explains exactly what it is, and

how, a DXA machine measures what it measures.

Nor why the DXA output measure is grams per SQUARE (sic) centimeter.

Which does not superficially appear to make a lot of sense.

Rodney.