Absolute and relative deficit in total-skeletal calcium and radial bone mineral in osteoporosis.

cium content of the skeleton in a group of 40 osteoporotic patients as measured by total-body neutron activation analysis (TBNAA). A highly significant correlation (0.826, p < 0.001 ) was found betweenthe bone mineralcontent of the radius (measured by absorptiometric tech nique) and total-body calcium (measured by TBNAA). However, the correlation was not as high as in the group of normal subjects (0.973, p < 0.001). In order to measure the relative deficit in total-body calcium in individual patients from the absolute calcium measurement, it was nec essary to normalize the data for sex, age, and skeletal size. For this purpose an algorithm was used to predict the normal skeletal calcium in each subject based on lean-body mass, height, sex, and age. In the female osteoporotic group the mean normalized total-body calcium ratio was 0.82 compared with a mean value of 1.00