Total and local bone mass before and after normalization for indices of bone and body size.

Both single and dual photon absorptiometry are excellent techniques for longitudinal studies, owing to their high precision. Because of large biological variations they are less suited for diagnosing bone disease in single subjects. In a homogeneous group of 161 women, bone mass in the distal forearm, spine, and whole body measured by photon absorptiometry was significantly related to various general indices of body size (r = 0.29-0.59). Normalization procedures for variations of these variables could only reduce the individual variation by 10-20%. Local indices of body size (i.e. bone width or scan area) were no better in the forearm or spine. Normalization for the projected skeletal area of the whole body could reduce the SD of the total body bone mineral (TBBM) from 322 to 126 grams (15-6%). This might imply that the normalized TBBM can be used for diagnostic purposes.