Measurement of bone mineral content in vivo using photon absorptiometry.

Progress in evaluating treatment of systemic bone disease has been hampered in the past by lack of precise in vivo quantitative techniques. Recently a method has been developed for measurement of bone mineral content (BMC), based on bone absorption of low-energy monochromatic radiation. This paper discusses a technique of photon absorptiometry using (125)l as a collimated point source. The technique is simple, with accuracy and precision within 2%.BMC and bone width (W) were measured in the distal radius of 359 normal subjects ranging in age from 5 to 82 years. A "normal" curve of BMC/W with age as the independent variable was then obtained from this population and was constructed for each sex. A positive correlation of BMC/W with height and body weight was found in a group of normal males.A series of patients with osteoporosis or malabsorption, or undergoing hemodialysis or steroid treatment, was then assessed in order to demonstrate changes in BMC/W that may occur secondary to disease or disturbances in calcium metabolism. Many of these patients were found to have a BMC/W below the normal mean value for their age and sex.