Correlation of radial bone mineral content with total-body calcium in various metabolic disorders

From international conference on bone mineral measurement; Chicago, Illinois, USA (12 Oct 1973). Loss of bone mineral content of the skeleton in osteoporosis and in other metabolic disorders can be measured directly by totalbody neutron activation analysis (TBNAA). The densitometric technique (using monochromatic photons from /sup 125/I) applied to the appendicular skeleton (radius) also reflects the loss of bone mineral in osteoporosis. In the present study the results of these two techniques are compared in 80 patients with various metabolic disorders and in 9 normal contrast subjects. It is apparent that there is good correlation between total body calcium (TBCa) and bone mineral content (BMC) in all groups studied. The correlation was highest in the normal contrast group (0.97) and alcoholics(0.98) and lowest in osteoporotic patients (0.83) and in renal patients on dialysis (0.84). In order to measure the relative deficit in TBCa in individual patients from the absolute calcium measurement, it is necessary to normalize the data for sex, age, and skeletal size. For this purpose an algorithm was used to predict the normal skeletal Ca in each subject bascd on weight, height, sex and age. In similar manner, BMC data were normalized using the same algorithm. These normalization procedures allow both the TBCa and BMC measurement of the radius to be used to compare the Ca deficit in individuals with different metabolic disorders. (auth