Densitometry of the Peripheral Skeleton to Detect Osteopenia-Reply

In Reply.— Dr Bilbrey alleges that there is evidence that the distal radius provides an early indication of osteopenia useful for diagnosis of osteoporosis. He presumes that this is due to a higher trabecular content at a "5-mm" radius site used in the Beta Diagnostics clinics. The 5-mm site is located at from 5% to 10% of theforearm length, where there is only 35% trabecular bone, not more than 50% as claimed.1The trabecular content is immaterial however, since even purely trabecular bone of the distal radius (1) is poorly correlated with that of the axial skeleton,2,3(2) has an onset of bone loss a decade after that in the spine and the femur, (3) has a low rate of aging bone loss,3,4and (4) does not respond to various therapies used for osteoporosis.5,6 Peripheral measurements could be clinically useful if they predicted bone density